Статті в журналах: "Driven diffusive model"

1

LI, YAN, LINYAN ZHANG, DAGEN LI, and HONG-BO SHI. "SPATIOTEMPORAL DYNAMICS OF A DIFFUSIVE LESLIE-TYPE PREDATOR–PREY MODEL WITH BEDDINGTON–DEANGELIS FUNCTIONAL RESPONSE." Journal of Biological Systems 28, no. 03 (August 28, 2020): 785–809. http://dx.doi.org/10.1142/s0218339020500175.

Повний текст джерела

Анотація:

In this paper, we study the spatiotemporal dynamics of a diffusive Leslie-type predator–prey system with Beddington–DeAngelis functional response under homogeneous Neumann boundary conditions. Preliminary analysis on the local asymptotic stability and Hopf bifurcation of the spatially homogeneous model based on ordinary differential equations is presented. For the diffusive model, firstly, it is shown that Turing (diffusion-driven) instability occurs which induces spatial inhomogeneous patterns. Next, it is proved that the diffusive model exhibits Hopf bifurcation which produces temporal inhomogeneous patterns. Furthermore, at the points where the Turing instability curve and Hopf bifurcation curve intersect, it is demonstrated that the diffusive model undergoes Turing–Hopf bifurcation and exhibits spatiotemporal patterns. Numerical simulations are also presented to verify the theoretical results.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

O’Loan, O. J., M. R. Evans, and M. E. Cates. "Shear-induced clustering in a simple driven diffusive model." Physica A: Statistical Mechanics and its Applications 258, no. 1-2 (September 1998): 109–22. http://dx.doi.org/10.1016/s0378-4371(98)00225-8.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Botto, D., A. Pelizzola, and M. Pretti. "Dynamical transitions in a driven diffusive model with interactions." EPL (Europhysics Letters) 124, no. 5 (December 27, 2018): 50004. http://dx.doi.org/10.1209/0295-5075/124/50004.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Pawlik, Grzegorz, Tomasz Wysoczanski, and Antoni Mitus. "Complex Dynamics of Photoinduced Mass Transport and Surface Relief Gratings Formation." Nanomaterials 9, no. 3 (March 4, 2019): 352. http://dx.doi.org/10.3390/nano9030352.

Повний текст джерела

Анотація:

The microscopic and semi-macroscopic mechanisms responsible for photoinduced mass transport in functionalized azo-polymers are far from deeply understood. To get some insight into those mechanisms on “microscopic” scale, we studied the directed photoinduced motion of single functionalized polymer chains under various types of polarized light illumination using Monte Carlo bond fluctuation model and our kinetic Monte Carlo model for photoinduced mass transport. We found sub-diffusive, diffusive and super-diffusive regimes of the dynamics of single chains at constant illumination and mostly super-diffusive regime for directed motion in the presence of the gradient of light intensity. This regime is more enhanced for long than for short chains and it approaches the ballistic limit for very long chains. We propose a physical picture of light-driven inscription of Surface Relief Gratings (SRG) as corresponding to a dynamical coexistence of normal and anomalous diffusion in various parts of the system. A simple continuous time random walk model of SRG inscription based on this physical picture reproduced the light-driven mass transport found in experiments as well as the fine structure of SRG.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Souna, Fethi, Salih Djilali, and Fayssal Charif. "Mathematical analysis of a diffusive predator-prey model with herd behavior and prey escaping." Mathematical Modelling of Natural Phenomena 15 (2020): 23. http://dx.doi.org/10.1051/mmnp/2019044.

Повний текст джерела

Анотація:

In this paper, we consider a new approach of prey escaping from herd in a predator-prey model with the presence of spatial diffusion. First, the sensitivity of the equilibrium state density with respect to the escaping rate has been studied. Then, the analysis of the non diffusive system was investigated where boundedness, local, global stability, Hopf bifurcation are obtained. Besides, for the diffusive system, we proved the occurrence of Hopf bifurcation and the non existence of diffusion driven instability. Furthermore, the direction of Hopf bifurcation has been proved using the normal form on the center manifold. Some numerical simulations have been used to illustrate the obtained results.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Eroglu, Fatma G., Songul Kaya, and Leo G. Rebholz. "POD-ROM for the Darcy–Brinkman equations with double-diffusive convection." Journal of Numerical Mathematics 27, no. 3 (September 25, 2019): 123–39. http://dx.doi.org/10.1515/jnma-2017-0122.

Повний текст джерела

Анотація:

Abstract This paper extends proper orthogonal decomposition reduced order modeling to flows governed by double diffusive convection, which models flow driven by two potentials with different rates of diffusion. We propose a reduced model based on proper orthogonal decomposition, present a stability and convergence analyses for it, and give results for numerical tests on a benchmark problem which show it is an effective approach to model reduction in this setting.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Elwakil, Sayed A., Mohsen A. Zahran, Refaat Sabry, and Emad K. El-Shewy. "New Travelling Wave Solutions for an Asymmetric Model of a Rod in a Lattice Fluid with Nonlinear Advection." Zeitschrift für Naturforschung A 61, no. 9 (September 1, 2006): 430–38. http://dx.doi.org/10.1515/zna-2006-0902.

Повний текст джерела

Анотація:

Based on the modified extended tanh-function method, we consider the continuum problem of the driven diffusive flow of particles behind an impenetrable obstacle (rod) of the length L. The results show that the presence of an obstacle, whether stationary or moving, in a driven diffusive flow with nonlinear drift will distort the local concentration profile to a state which divided the (x,y)-plane into two regions. The concentration is relatively higher in one side than the other side, apart from the value of , where D is the diffusion coefficient and v is the drift velocity. This problem has relevance for the size segregation of particulate matter which results from the relative motion of different-size paricles induced by shaking. The obtained soultions include soliton, periodical, rational and singular solutions.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Christensen, Ulrich R., Julien Aubert, and Peter Olson. "Convection-driven planetary dynamos." Proceedings of the International Astronomical Union 2, S239 (August 2006): 188–95. http://dx.doi.org/10.1017/s1743921307000403.

Повний текст джерела

Анотація:

AbstractNumerical simulations of convection-driven dynamos in rotating spherical shells are employed to better understand the observed strength and geometry of planetary magnetic fields. The model computations cannot be performed for realistic values of several of the control parameters. By varying parameters within the accessible range, it is possible to derive scaling laws for the magnetic field strength and the flow velocity in the dynamo region and for the dipole moment. Our scaling laws suggest that, even though diffusivities are far too large in the models, diffusive processes do not play an important role, just as in planetary cores. Extrapolating the scaling laws to planetary values of the control parameters leads to reasonable predictions for the field strength in the dynamo region and fits the observed dipole moments decently, in particular in the cases of Earth and Jupiter. For Mercury, which does not fit well when applying the scaling laws in a straightforward way, a model is proposed in which the upper part of the fluid core is stably stratified and the dynamo operates only in its deep regions. The time-varying dynamo field must diffuse through the stable region and is attenuated by the skin effect. The model explains why Mercury has a very weak but probably dipole-dominated magnetic field.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Zhou, Jun. "Bifurcation Analysis of a Diffusive Predator–Prey Model with Bazykin Functional Response." International Journal of Bifurcation and Chaos 29, no. 10 (September 2019): 1950136. http://dx.doi.org/10.1142/s0218127419501360.

Повний текст джерела

Анотація:

This paper deals with a diffusive predator–prey model with Bazykin functional response. The parameter regions for the stability and instability of the unique constant steady state are derived. The Turing (diffusion-driven) instability which induces spatial inhomogeneous patterns, the existence of time-periodic orbits which produce temporal inhomogeneous patterns, the existence and nonexistence of nonconstant steady state positive solutions are proved. Numerical simulations are presented to verify and illustrate the theoretical results.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Cao, Pei-Chao, Yu-Gui Peng, Ying Li, and Xue-Feng Zhu. "Phase-Locking Diffusive Skin Effect." Chinese Physics Letters 39, no. 5 (April 1, 2022): 057801. http://dx.doi.org/10.1088/0256-307x/39/5/057801.

Повний текст джерела

Анотація:

We explore the exceptional point (EP) induced phase transition and amplitude/phase modulation in thermal diffusion systems. We start from the asymmetric coupling double-channel model, where the temperature field is unbalanced in the amplitude and locked in the symmetric phase. By extending into the one-dimensional tight-binding non-Hermitian lattice, we study the convection-driven phase locking and the asymmetric-couplinginduced diffusive skin effect with the high-order EPs in static systems. Combining convection and asymmetric couplings, we further show the phase-locking diffusive skin effect. Our work reveals the mechanism of controlling both the amplitude and phase of temperature fields in thermal coupling systems and has potential applications in non-Hermitian topology in thermal diffusion.

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Feunou, Bruno, and Cédric Okou. "Good Volatility, Bad Volatility, and Option Pricing." Journal of Financial and Quantitative Analysis 54, no. 2 (September 13, 2018): 695–727. http://dx.doi.org/10.1017/s0022109018000777.

Повний текст джерела

Анотація:

Advances in variance analysis permit the splitting of the total quadratic variation of a jump-diffusion process into upside and downside components. Recent studies establish that this decomposition enhances volatility predictions and highlight the upside/downside variance spread as a driver of the asymmetry in stock price distributions. To appraise the economic gain of this decomposition, we design a new and flexible option pricing model in which the underlying asset price exhibits distinct upside and downside semivariance dynamics driven by the model-free proxies of the variances. The new model outperforms common benchmarks, especially the alternative that splits the quadratic variation into diffusive and jump components.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

PANDEY, R. B., WARREN T. WOOD, and J. F. GETTRUST. "GRADIENT DRIVEN FLOW: LATTICE GAS, DIFFUSION EQUATION AND MEASUREMENT SCALES." International Journal of Modern Physics C 12, no. 02 (February 2001): 273–79. http://dx.doi.org/10.1142/s0129183101001687.

Повний текст джерела

Анотація:

Tracer diffusion and fluid transport are studied in a model for a geomarine system in which fluid constituents move from regions of high to low concentration. An interacting lattice gas is used to model the system. Collective diffusion of fluid particles in lattice gas is consistent with the solution of the continuum diffusion equation for the concentration profile. Comparison of these results validates the applicability and provides a calibration for arbitrary (time and length) units of the lattice gas. Unlike diffusive motion in an unsteady-state regime, both fluid and tracer exhibit a drift-like transport in a steady-state regime. The transverse components of fluid and tracer displacements differ significantly. While the average tracer motion becomes nondiffusive in the long time regime, the collective motion exhibits an onset of oscillation.

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Vallés, J. L. "Nonequilibrium phase transition in a driven diffusive model with anisotropic couplings." Journal de Physique I 2, no. 7 (July 1992): 1361–68. http://dx.doi.org/10.1051/jp1:1992215.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Rosevear, Madelaine Gamble, Bishakhdatta Gayen, and Benjamin Keith Galton-Fenzi. "The role of double-diffusive convection in basal melting of Antarctic ice shelves." Proceedings of the National Academy of Sciences 118, no. 6 (February 5, 2021): e2007541118. http://dx.doi.org/10.1073/pnas.2007541118.

Повний текст джерела

Анотація:

The Antarctic Ice Sheet loses about half its mass through ocean-driven melting of its fringing ice shelves. However, the ocean processes governing ice shelf melting are not well understood, contributing to uncertainty in projections of Antarctica’s contribution to global sea level. We use high-resolution large-eddy simulation to examine ocean-driven melt, in a geophysical-scale model of the turbulent ice shelf–ocean boundary layer, focusing on the ocean conditions observed beneath the Ross Ice Shelf. We quantify the role of double-diffusive convection in determining ice shelf melt rates and oceanic mixed layer properties in relatively warm and low-velocity cavity environments. We demonstrate that double-diffusive convection is the first-order process controlling the melt rate and mixed layer evolution at these flow conditions, even more important than vertical shear due to a mean flow, and is responsible for the step-like temperature and salinity structure, or thermohaline staircase, observed beneath the ice. A robust feature of the multiday simulations is a growing saline diffusive sublayer that drives a time-dependent melt rate. This melt rate is lower than current ice–ocean parameterizations, which consider only shear-controlled turbulent melting, would predict. Our main finding is that double-diffusive convection is an important process beneath ice shelves, yet is currently neglected in ocean–climate models.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Alber, Hans-Dieter, and Peicheng Zhu. "Interface motion by interface diffusion driven by bulk energy: justification of a diffusive interface model." Continuum Mechanics and Thermodynamics 23, no. 2 (August 10, 2010): 139–76. http://dx.doi.org/10.1007/s00161-010-0162-9.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Schmittmann, B. "CRITICAL BEHAVIOR OF THE DRIVEN DIFFUSIVE LATTICE GAS." International Journal of Modern Physics B 04, no. 15n16 (December 1990): 2269–306. http://dx.doi.org/10.1142/s0217979290001066.

Повний текст джерела

Анотація:

This paper reviews simulational and theoretical investigations of critical behavior in a stochastic, interacting lattice gas under the influence of a uniform external driving field. By studying this model system one wishes to gain a deeper understanding of steady states far from thermal equilibrium, and their dynamic universality classes. The major result in the case of attractive particle-particle interactions is the emergence of a novel non-equilibrium fixed point, different from the Wilson-Fisher fixed point of the equilibrium system. The fluctuations of internal energy, the structure factor and the two-point correlations all display surprising features associated with the non-equilibrium nature of the system. For repulsive interactions and small driving forces, one finds a continuous, Ising-like transition which turns first order for larger fields until it is completely destroyed.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Nowok, J. W. "A model of diffusion/viscous mass transport in silicates during liquid-phase sintering." Journal of Materials Research 10, no. 2 (February 1995): 401–4. http://dx.doi.org/10.1557/jmr.1995.0401.

Повний текст джерела

Анотація:

The model of capillary transport of liquid metals driven by shear stress resulting from the displacement of menisci [J.W. Nowok, Scripta Metal]. Mater. 29, 931 (1993); Acta Metall. Mater. 42, 4025 (1994)] is applicable to liquid-phase sintering of silicate/aluminosilicate glasses. The movement of a liquid phase between adjacent particles is compared with that in capillaries. It appears that the transport property of intergranular melt may be expressed by the viscosity (η) and volume diffusion (D) parameters if mean displacement of menisci is compared with the mean diffusive jump lengths of atoms/molecules (L). This leads to the following relation: (γ/η)Lα = Dcap, where α and Dcap are a specific permeability and volume diffusion coefficient. The use of this model requires the assumption that the diffusing species are also the viscous flow units, and they can be either atoms or structural units. This assumption seems to be applicable for depolymerized silicate melts if the dominant mass transport is initiated by the diffusion of both nonbridging oxygen and silicon atoms.

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Sauter, Anne I., and W. D. Nix. "A study of stress-driven diffusive growth of voids in encapsulated interconnect lines." Journal of Materials Research 7, no. 5 (May 1992): 1133–43. http://dx.doi.org/10.1557/jmr.1992.1133.

Повний текст джерела

Анотація:

Stress-driven diffusive growth of voids in encapsulated interconnect lines is studied. By calculating the rate of growth of a single void in a passivated line subjected to an initial hydrostatic tension stress and by assuming that failure occurs when the void reaches a critical size, a model for failure of encapsulated interconnect lines by stress voiding can be developed. The model for the prediction of void growth and failure is based on two limiting kinds of void growth. In one limit, which applies at short times, radial displacements occur by diffusional flow processes around the growing void and relax the local hydrostatic tension stress. In the long time limit, vacancies flow to the void from distant parts of the line by diffusion along grain boundaries, thereby relaxing the stress in a growing section of the line. A model based on a combination of these behaviors leads to a failure law for aluminum lines of the form tfσ2/d = 1019.2 exp(Q/RT) where tf is the failure time in seconds, σ is the initial hydrostatic tension stress in the line in Pa, d is the grain size in meters, and the activation energy, Q = 80.9 kJ/mol, is close to that for grain boundary diffusion in aluminum. The model predictions appear to be in good agreement with the few experiments on stress voiding that have been conducted.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Andersen, Jørgen Vitting, Henrik Jeldtoft Jensen, and Ole G. Mouritsen. "Crossover in the power spectrum of a driven diffusive lattice-gas model." Physical Review B 44, no. 1 (July 1, 1991): 439–42. http://dx.doi.org/10.1103/physrevb.44.439.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Shi, Hong-Bo, Shigui Ruan, Ying Su, and Jia-Fang Zhang. "Spatiotemporal Dynamics of a Diffusive Leslie–Gower Predator–Prey Model with Ratio-Dependent Functional Response." International Journal of Bifurcation and Chaos 25, no. 05 (May 2015): 1530014. http://dx.doi.org/10.1142/s0218127415300141.

Повний текст джерела

Анотація:

This paper is devoted to the study of spatiotemporal dynamics of a diffusive Leslie–Gower predator–prey system with ratio-dependent Holling type III functional response under homogeneous Neumann boundary conditions. It is shown that the model exhibits spatial patterns via Turing (diffusion-driven) instability and temporal patterns via Hopf bifurcation. Moreover, the existence of spatiotemporal patterns is established via Turing–Hopf bifurcation at the degenerate points where the Turing instability curve and the Hopf bifurcation curve intersect. Various numerical simulations are also presented to illustrate the theoretical results.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

TREVELYAN, P. M. J., C. ALMARCHA, and A. DE WIT. "Buoyancy-driven instabilities of miscible two-layer stratifications in porous media and Hele-Shaw cells." Journal of Fluid Mechanics 670 (January 31, 2011): 38–65. http://dx.doi.org/10.1017/s0022112010005008.

Повний текст джерела

Анотація:

Buoyancy-driven instabilities of a horizontal interface between two miscible solutions in the gravity field are theoretically studied in porous media and Hele-Shaw cells (two glass plates separated by a thin gap). Beyond the classical Rayleigh–Taylor (RT) and double diffusive (DD) instabilities that can affect such two-layer stratifications right at the initial time of contact, diffusive-layer convection (DLC) as well as delayed-double diffusive (DDD) instabilities can set in at a later time when differential diffusion effects act upon the evolving density profile starting from an initial step-function profile between the two miscible solutions. The conditions for these instabilities to occur can therefore be obtained only by considering time evolving base-state profiles. To do so, we perform a linear stability analysis based on a quasi-steady-state approximation (QSSA) as well as nonlinear simulations of a diffusion–convection model to classify and analyse all possible buoyancy-driven instabilities of a stratification of a solution of a given solute A on top of another miscible solution of a species B. Our theoretical model couples Darcy's law to evolution equations for the concentration of species A and B ruling the density of the miscible solutions. The parameters of the problem are a buoyancy ratio R quantifying the ratio of the relative contribution of B and A to the density as well as δ, the ratio of diffusion coefficients of these two species. We classify the region of RT, DD, DDD and DLC instabilities in the (R, δ) plane as a function of the elapsed time and show that, asymptotically, the unstable domain is much larger than the one captured on the basis of linear base-state profiles which can only obtain stability thresholds for the RT and DD instabilities. In addition the QSSA allows one to determine the critical time at which an initially stable stratification of A above B can become unstable with regard to a DDD or DLC mechanism when starting from initial step function profiles. Nonlinear dynamics are also analysed by a numerical integration of the full nonlinear model in order to understand the influence of R and δ on the dynamics.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Kuzmina, Natalia, Bert Rudels, Tapani Stipa, and Victor Zhurbas. "The Structure and Driving Mechanisms of the Baltic Intrusions." Journal of Physical Oceanography 35, no. 6 (June 1, 2005): 1120–37. http://dx.doi.org/10.1175/jpo2749.1.

Повний текст джерела

Анотація:

Abstract Data from closely spaced CTD profiling performed in the eastern Gotland Basin after the 1993 inflow event are used to study thermohaline intrusions in the Baltic Sea. Two CTD cross sections display abundant intrusive layers in the permanent halocline. Despite the overwhelming dominance of the salinity stratification, diffusive convection is shown to work in the Baltic halocline enhancing diapycnical mixing. To understand the driving mechanisms of observed intrusions, these are divided into different types depending on their structural features. Only two types of observed intrusions are suggested to be strongly influenced by diffusive convection: 1) relatively thin (3–5 m) and long (up to 8 km) intrusions inherent to high-baroclinicity regions and 2) relatively thick (∼10 m) and short (2–5 km) intrusions inherent to low-baroclinicity regions. To verify this hypothesis the linear stability models of 3D and 2D double-diffusive interleaving in approximation of a finite-width front were used. It is shown that the horizontal and vertical scales of thick and short intrusions correspond well to the 3D rotational mode for a pure thermohaline front. Since mesoscale thermohaline fronts in the Baltic halocline are shown to be essentially baroclinic, the influence of baroclinicity on the rotational mode was studied, which resulted in more adequate estimates of the growth rate of the unstable modes. The thin and long intrusions are shown to be likely driven by 2D baroclinic instability triggered by diffusive convection. The model results demonstrated that diffusion convection can be considered as a possible driver for some intrusions observed in the Baltic halocline, while most of the intrusions have a non-double-diffusive origin. Nevertheless, diffusive convection can affect all types of observed intrusions, for example, by tilting them relative to isopycnals and thereby promoting diapycnal mixing and ventilation in the Baltic halocline.

Стилі APA, Harvard, Vancouver, ISO та ін.

23

ALONSO, R., M. SANTILLANA, and C. DAWSON. "On the diffusive wave approximation of the shallow water equations." European Journal of Applied Mathematics 19, no. 5 (October 2008): 575–606. http://dx.doi.org/10.1017/s0956792508007675.

Повний текст джерела

Анотація:

In this paper, we study basic properties of the diffusive wave approximation of the shallow water equations (DSW). This equation is a doubly non-linear diffusion equation arising in shallow water flow models. It has been used as a model to simulate water flow driven mainly by gravitational forces and dominated by shear stress, that is, under uniform and fully developed turbulent flow conditions. The aim of this work is to present a survey of relevant results coming from the studies of doubly non-linear diffusion equations that can be applied to the DSW equation when topographic effects are ignored. In fact, we present proofs of the most relevant results existing in the literature using constructive techniques that directly lead to the implementation of numerical algorithms to obtain approximate solutions.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Chen, Meijun, Shengmao Fu, and Xiaoli Yang. "Global Behavior of Solutions in a Predator-Prey Cross-Diffusion Model with Cannibalism." Complexity 2020 (May 22, 2020): 1–19. http://dx.doi.org/10.1155/2020/1265798.

Повний текст джерела

Анотація:

The global asymptotic behavior of solutions in a cross-diffusive predator-prey model with cannibalism is studied in this paper. Firstly, the local stability of nonnegative equilibria for the weakly coupled reaction-diffusion model and strongly coupled cross-diffusion model is discussed. It is shown that the equilibria have the same stability properties for the corresponding ODE model and semilinear reaction-diffusion model, but under suitable conditions on reaction coefficients, cross-diffusion-driven Turing instability occurs. Secondly, the uniform boundedness and the global existence of solutions for the model with SKT-type cross-diffusion are investigated when the space dimension is one. Finally, the global stability of the positive equilibrium is established by constructing a Lyapunov function. The result indicates that, under certain conditions on reaction coefficients, the model has no nonconstant positive steady state if the diffusion matrix is positive definite and the self-diffusion coefficients are large enough.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Carvalho, Sylvestre, Henrique Mota, and Marcelo Martins. "Landscapes of Biochemical Warfare: Spatial Self-Organization Woven from Allelopathic Interactions." Life 13, no. 2 (February 13, 2023): 512. http://dx.doi.org/10.3390/life13020512.

Повний текст джерела

Анотація:

Evidence shows that diversity and spatial distributions of biological communities are largely driven by the race of living organisms in their adaptation to chemicals synthesized by their neighbors. In this report, the emergence of mathematical models on pure spatial self-organization induced by biochemical suppression (allelopathy) and competition between species were investigated through numerical analysis. For both random and patched initial spatial distributions of species, we demonstrate that warfare survivors are self-organized on the landscape in Turing-like patterns driven by diffusive instabilities of allelochemicals. These patterns are simple; either all species coexist at low diffusion rates or are massively extinct, except for a few at high diffusivities, but they are complex and biodiversity-sustained at intermediate diffusion rates. “Defensive alliances” and ecotones seem to be basic mechanisms that sustain great biodiversity in our hybrid cellular automata model. Moreover, species coexistence and extinction exhibit multi-stationarity.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

MON, K. K. "MONTE CARLO STUDIES OF A NEW MODEL DRIVEN DIFFUSIVE SYSTEM WITH REPULSIVE INTERACTIONS." Modern Physics Letters B 06, no. 26 (November 10, 1992): 1673–79. http://dx.doi.org/10.1142/s021798499200137x.

Повний текст джерела

Анотація:

We propose a new class of driven lattice gas with repulsive nearest-neighbor interactions. Particles are allowed to jump to empty next-nearest-neighbor (nnn) sites in addition to the standard nearest-neighbor moves. In contrast to previous model with repulsive interactions, the external driving field (E) acts only along the nnn directions and does not destroy ground state sublattice ordering. Extensive Monte Carlo simulations in two dimensions for small E are consistent with a line of continuous transitions with Ising exponents. First-order transitions are also found for larger E.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

RADKO, TIMOUR. "The double-diffusive modon." Journal of Fluid Mechanics 609 (July 31, 2008): 59–85. http://dx.doi.org/10.1017/s0022112008002127.

Повний текст джерела

Анотація:

Fully developed two-dimensional salt-finger convection is characterized by the appearance of coherent dipolar eddies which carry relatively fresh and cold fluid upward and salty and warm fluid downward. Such structures – the double-diffusive modons – are prevalent in the regime in which density stratification is close to neutral and the salt-finger instability is extremely vigorous. The structure and translation velocities of modons are discussed in terms of the asymptotic expansion in which the background density ratio approaches unity. It is argued that the vertical salt flux is driven primarily by double-diffusive modons, which makes it possible to derive explicit expressions for the mixing rates of temperature and salinity as a function of their background gradients. Predictions of the proposed mixing model are successfully tested by direct numerical simulations.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Filliger, Roger, and Max-Olivier Hongler. "Explicit Gittins Indices for a Class of Superdiffusive Processes." Journal of Applied Probability 44, no. 2 (June 2007): 554–59. http://dx.doi.org/10.1239/jap/1183667421.

Повний текст джерела

Анотація:

We explicitly calculate the dynamic allocation indices (i.e. the Gittins indices) for multi-armed Bandit processes driven by superdiffusive noise sources. This class of model generalizes former results derived by Karatzas for diffusive processes. In particular, the Gittins indices do, in this soluble class of superdiffusive models, explicitly depend on the noise state.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Filliger, Roger, and Max-Olivier Hongler. "Explicit Gittins Indices for a Class of Superdiffusive Processes." Journal of Applied Probability 44, no. 02 (June 2007): 554–59. http://dx.doi.org/10.1017/s0021900200118029.

Повний текст джерела

Анотація:

We explicitly calculate the dynamic allocation indices (i.e. the Gittins indices) for multi-armed Bandit processes driven by superdiffusive noise sources. This class of model generalizes former results derived by Karatzas for diffusive processes. In particular, the Gittins indices do, in this soluble class of superdiffusive models, explicitly depend on the noise state.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Filliger, Roger, and Max-Olivier Hongler. "Explicit Gittins Indices for a Class of Superdiffusive Processes." Journal of Applied Probability 44, no. 02 (June 2007): 554–59. http://dx.doi.org/10.1017/s0021900200003168.

Повний текст джерела

Анотація:

We explicitly calculate the dynamic allocation indices (i.e. the Gittins indices) for multi-armed Bandit processes driven by superdiffusive noise sources. This class of model generalizes former results derived by Karatzas for diffusive processes. In particular, the Gittins indices do, in this soluble class of superdiffusive models, explicitly depend on the noise state.

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Bouin, Emeric, Vincent Calvez, and Grégoire Nadin. "Hyperbolic traveling waves driven by growth." Mathematical Models and Methods in Applied Sciences 24, no. 06 (March 28, 2014): 1165–95. http://dx.doi.org/10.1142/s0218202513500802.

Повний текст джерела

Анотація:

We perform the analysis of a hyperbolic model which is the analog of the Fisher-KPP equation. This model accounts for particles that move at maximal speed ϵ-1 (ϵ > 0), and proliferate according to a reaction term of monostable type. We study the existence and stability of traveling fronts. We exhibit a transition depending on the parameter ϵ: for small ϵ the behavior is essentially the same as for the diffusive Fisher-KPP equation. However, for large ϵ the traveling front with minimal speed is discontinuous and travels at the maximal speed ϵ-1. The traveling fronts with minimal speed are linearly stable in weighted L2 spaces. We also prove local nonlinear stability of the traveling front with minimal speed when ϵ is smaller than the transition parameter.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Uritsky, V. M., and A. J. Klimas. "Hysteresis-controlled instability waves in a scale-free driven current sheet model." Nonlinear Processes in Geophysics 12, no. 6 (September 20, 2005): 827–33. http://dx.doi.org/10.5194/npg-12-827-2005.

Повний текст джерела

Анотація:

Abstract. Magnetospheric dynamics is a complex multiscale process whose statistical features can be successfully reproduced using high-dimensional numerical transport models exhibiting the phenomenon of self-organized criticality (SOC). Along this line of research, a 2-dimensional driven current sheet (DCS) model has recently been developed that incorporates an idealized current-driven instability with a resistive MHD plasma system (Klimas et al., 2004a, b). The dynamics of the DCS model is dominated by the scale-free diffusive energy transport characterized by a set of broadband power-law distribution functions similar to those governing the evolution of multiscale precipitation regions of energetic particles in the nighttime sector of aurora (Uritsky et al., 2002b). The scale-free DCS behavior is supported by localized current-driven instabilities that can communicate in an avalanche fashion over arbitrarily long distances thus producing current sheet waves (CSW). In this paper, we derive the analytical expression for CSW speed as a function of plasma parameters controlling local anomalous resistivity dynamics. The obtained relation indicates that the CSW propagation requires sufficiently high initial current densities, and predicts a deceleration of CSWs moving from inner plasma sheet regions toward its northern and southern boundaries. We also show that the shape of time-averaged current density profile in the DCS model is in agreement with steady-state spatial configuration of critical avalanching models as described by the singular diffusion theory of the SOC. Over shorter time scales, SOC dynamics is associated with rather complex spatial patterns and, in particular, can produce bifurcated current sheets often seen in multi-satellite observations.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Bettaibi, Soufiene, Frédéric Kuznik, Ezeddine Sediki, and Sauro Succi. "Numerical Study of Thermal Diffusion and Diffusion Thermo Effects in a Differentially Heated and Salted Driven Cavity Using MRT-Lattice Boltzmann Finite Difference Model." International Journal of Applied Mechanics 13, no. 04 (May 2021): 2150049. http://dx.doi.org/10.1142/s1758825121500496.

Повний текст джерела

Анотація:

We perform a numerical study of thermal diffusion and diffusion thermo effects on double diffusive mixed convection in a driven square cavity, differentially heated and salted using a hybrid lattice Boltzmann solver. The multiple relaxation time (MRT) for the lattice Boltzmann equation is used to obtain the velocity field whereas the temperature and concentration fields are deduced from energy and species balances equations using a finite difference method (FDM). The model is validated, resulting in satisfactory agreement with data from the literature. The different validations demonstrate the effectiveness of the proposed approach. Besides, the results showed that the Soret and Dufour numbers have great effects on the flow structure and heat and mass transfer.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Xiang, Nan, Aying Wan, and Hongyan Lin. "Diffusion-driven instability of both the equilibrium solution and the periodic solutions for the diffusive Sporns-Seelig model." Electronic Research Archive 30, no. 3 (2022): 813–29. http://dx.doi.org/10.3934/era.2022043.

Повний текст джерела

Анотація:

<abstract><p>In this paper, a reaction-diffusion Sporn-Seelig model subject to homogeneous Neumann boundary condition in the one dimensional spatial open bounded domain is considered. Of our particular interests, we are concerned with diffusion-driven instability of both the positive constant equilibrium solution and the Hopf bifurcating spatially homogeneous periodic solutions. To strengthen our analytical results, we also include some numerical simulations. These results allow for the clearer understanding the mechanisms of the spatiotemporal pattern formations of this chemical reaction model.</p></abstract>

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Aschwanden, M. J. "A statistical fractal-diffusive avalanche model of a slowly-driven self-organized criticality system." Astronomy & Astrophysics 539 (February 17, 2012): A2. http://dx.doi.org/10.1051/0004-6361/201118237.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Zhao, Jianglin, Yong Yan, Lizhuang Huang, and Run Yang. "Delay driven Hopf bifurcation and chaos in a diffusive toxin producing phytoplankton‐zooplankton model." Mathematical Methods in the Applied Sciences 42, no. 11 (April 29, 2019): 3831–47. http://dx.doi.org/10.1002/mma.5615.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Ghadermazi, Mohammad, and Farhad H. Jafarpour. "Non-equilibrium phase transition in a two-species driven-diffusive model of classical particles." Journal of Theoretical and Applied Physics 10, no. 3 (June 27, 2016): 195–202. http://dx.doi.org/10.1007/s40094-016-0215-y.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Zhang, Yanbin, Jincong He, Changdong Yang, Jiang Xie, Robert Fitzmorris, and Xian-Huan Wen. "A Physics-Based Data-Driven Model for History Matching, Prediction, and Characterization of Unconventional Reservoirs." SPE Journal 23, no. 04 (May 24, 2018): 1105–25. http://dx.doi.org/10.2118/191126-pa.

Повний текст джерела

Анотація:

Summary We developed a physics-based data-driven model for history matching, prediction, and characterization of unconventional reservoirs. It uses 1D numerical simulation to approximate 3D problems. The 1D simulation is formulated in a dimensionless space by introducing a new diffusive diagnostic function (DDF). For radial and linear flow, the DDF is shown analytically to be a straight line with a positive or zero slope. Without any assumption of flow regime, the DDF can be obtained in a data-driven manner by means of history matching using the ensemble smoother with multiple data assimilation (ES-MDA). The history-matched ensemble of DDFs offers diagnostic characteristics and probabilistic predictions for unconventional reservoirs.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Ruggiero, Matteo. "Species Dynamics in the Two-Parameter Poisson-Dirichlet Diffusion Model." Journal of Applied Probability 51, no. 1 (March 2014): 174–90. http://dx.doi.org/10.1239/jap/1395771422.

Повний текст джерела

Анотація:

The recently introduced two-parameter infinitely-many-neutral-alleles model extends the celebrated one-parameter version (which is related to Kingman's distribution) to diffusive two-parameter Poisson-Dirichlet frequencies. In this paper we investigate the dynamics driving the species heterogeneity underlying the two-parameter model. First we show that a suitable normalization of the number of species is driven by a critical continuous-state branching process with immigration. Secondly, we provide a finite-dimensional construction of the two-parameter model, obtained by means of a sequence of Feller diffusions of Wright-Fisher flavor which feature finitely many types and inhomogeneous mutation rates. Both results provide insight into the mathematical properties and biological interpretation of the two-parameter model, showing that it is structurally different from the one-parameter case in that the frequency dynamics are driven by state-dependent rather than constant quantities.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Ruggiero, Matteo. "Species Dynamics in the Two-Parameter Poisson-Dirichlet Diffusion Model." Journal of Applied Probability 51, no. 01 (March 2014): 174–90. http://dx.doi.org/10.1017/s0021900200010160.

Повний текст джерела

Анотація:

The recently introduced two-parameter infinitely-many-neutral-alleles model extends the celebrated one-parameter version (which is related to Kingman's distribution) to diffusive two-parameter Poisson-Dirichlet frequencies. In this paper we investigate the dynamics driving the species heterogeneity underlying the two-parameter model. First we show that a suitable normalization of the number of species is driven by a critical continuous-state branching process with immigration. Secondly, we provide a finite-dimensional construction of the two-parameter model, obtained by means of a sequence of Feller diffusions of Wright-Fisher flavor which feature finitely many types and inhomogeneous mutation rates. Both results provide insight into the mathematical properties and biological interpretation of the two-parameter model, showing that it is structurally different from the one-parameter case in that the frequency dynamics are driven by state-dependent rather than constant quantities.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

KAYE, N. B., M. R. FLYNN, M. J. COOK, and Y. JI. "The role of diffusion on the interface thickness in a ventilated filling box." Journal of Fluid Mechanics 652 (April 9, 2010): 195–205. http://dx.doi.org/10.1017/s0022112010000881.

Повний текст джерела

Анотація:

We examine the role of diffusivity, whether molecular or turbulent, on the steady-state stratification in a ventilated filling box. The buoyancy-driven displacement ventilation model of Linden et al. (J. Fluid Mech., vol. 212, 1990, p. 309) predicts the formation of a two-layer stratification when a single plume is introduced into an enclosure with vents at the top and bottom. The model assumes that diffusion plays no role in the development of the ambient buoyancy stratification: diffusion is a slow process and the entrainment of ambient fluid into the plume from the diffuse interface will act to thin the interface resulting in a near discontinuity of density between the upper and lower layers. This prediction has been corroborated by small-scale salt bath experiments; however, full-scale measurements in ventilated rooms and complementary numerical simulations suggest an interface that is not sharp but rather smeared out over a finite thickness. For a given plume buoyancy flux, as the cross-sectional area of the enclosure increases the volume of fluid that must be entrained by the plume to maintain a sharp interface also increases. Therefore the balance between the diffusive thickening of the interface and plume-driven thinning favours a thicker interface. Conversely, the interface thickness decreases with increasing source buoyancy flux, although the dependence is relatively weak. Our analysis presents two models for predicting the interface thickness as a function of the enclosure height, base area, composite vent area, plume buoyancy flux and buoyancy diffusivity. Model results are compared with interface thickness measurements based on previously reported data. Positive qualitative and quantitative agreement is observed.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Zehe, Erwin, and Conrad Jackisch. "A Lagrangian model for soil water dynamics during rainfall-driven conditions." Hydrology and Earth System Sciences 20, no. 9 (September 2, 2016): 3511–26. http://dx.doi.org/10.5194/hess-20-3511-2016.

Повний текст джерела

Анотація:

Abstract. Within this study we propose a stochastic approach to simulate soil water dynamics in the unsaturated zone by using a non-linear, space domain random walk of water particles. Soil water is represented by particles of constant mass, which travel according to the Itô form of the Fokker–Planck equation. The model concept builds on established soil physics by estimating the drift velocity and the diffusion term based on the soil water characteristics. A naive random walk, which assumes all water particles to move at the same drift velocity and diffusivity, overestimated depletion of soil moisture gradients compared to a Richards solver. This is because soil water and hence the corresponding water particles in smaller pore size fractions are, due to the non-linear decrease in soil hydraulic conductivity with decreasing soil moisture, much less mobile. After accounting for this subscale variability in particle mobility, the particle model and a Richards solver performed highly similarly during simulated wetting and drying circles in three distinctly different soils. Both models were in very good accordance during rainfall-driven conditions, regardless of the intensity and type of the rainfall forcing and the shape of the initial state. Within subsequent drying cycles the particle model was typically slightly slower in depleting soil moisture gradients than the Richards model. Within a real-world benchmark, the particle model and the Richards solver showed the same deficiencies in matching observed reactions of topsoil moisture to a natural rainfall event. The particle model performance, however, clearly improved after a straightforward implementation of rapid non-equilibrium infiltration, which treats event water as different types of particles, which travel initially in the largest pore fraction at maximum velocity and experience a slow diffusive mixing with the pre-event water particles. The proposed Lagrangian approach is hence a promising, easy-to-implement alternative to the Richards equation for simulating rainfall-driven soil moisture dynamics, which offers straightforward opportunities to account for preferential, non-equilibrium flow.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

MASHARIAN, SEYEDEH RAZIYEH, and FARHAD H. JAFARPOUR. "A HETEROGENEOUS ZERO-RANGE PROCESS RELATED TO A TWO-DIMENSIONAL WALK MODEL." International Journal of Modern Physics B 26, no. 09 (April 10, 2012): 1250044. http://dx.doi.org/10.1142/s0217979212500440.

Повний текст джерела

Анотація:

We have considered a disordered driven-diffusive system defined on a ring. This system can be mapped onto a heterogeneous zero-range process. We have shown that the grand-canonical partition function of this process can be obtained using a matrix product formalism and that it is exactly equal to the partition function of a two-dimensional walk model. The canonical partition function of this process is also calculated. Two simple examples are presented in order to confirm the results.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Charlesworth, Edward J., Ann-Kristin Dugstad, Frauke Fritsch, Patrick Jöckel, and Felix Plöger. "Impact of Lagrangian transport on lower-stratospheric transport timescales in a climate model." Atmospheric Chemistry and Physics 20, no. 23 (December 8, 2020): 15227–45. http://dx.doi.org/10.5194/acp-20-15227-2020.

Повний текст джерела

Анотація:

Abstract. We investigate the impact of model trace gas transport schemes on the representation of transport processes in the upper troposphere and lower stratosphere. Towards this end, the Chemical Lagrangian Model of the Stratosphere (CLaMS) was coupled to the ECHAM/MESSy Atmospheric Chemistry (EMAC) model and results from the two transport schemes (Lagrangian critical Lyapunov scheme and flux-form semi-Lagrangian, respectively) were compared. Advection in CLaMS was driven by the EMAC simulation winds, and thereby the only differences in transport between the two sets of results were caused by differences in the transport schemes. To analyze the timescales of large-scale transport, multiple tropical-surface-emitted tracer pulses were performed to calculate age of air spectra, while smaller-scale transport was analyzed via idealized, radioactively decaying tracers emitted in smaller regions (nine grid cells) within the stratosphere. The results show that stratospheric transport barriers are significantly stronger for Lagrangian EMAC-CLaMS transport due to reduced numerical diffusion. In particular, stronger tracer gradients emerge around the polar vortex, at the subtropical jets, and at the edge of the tropical pipe. Inside the polar vortex, the more diffusive EMAC flux-form semi-Lagrangian transport scheme results in a substantially higher amount of air with ages from 0 to 2 years (up to a factor of 5 higher). In the lowermost stratosphere, mean age of air is much smaller in EMAC, owing to stronger diffusive cross-tropopause transport. Conversely, EMAC-CLaMS shows a summertime lowermost stratosphere age inversion – a layer of older air residing below younger air (an “eave”). This pattern is caused by strong poleward transport above the subtropical jet and is entirely blurred by diffusive cross-tropopause transport in EMAC. Potential consequences from the choice of the transport scheme on chemistry–climate and geoengineering simulations are discussed.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Gao, Xiaoyan. "Nonconstant positive steady states and pattern formation of a diffusive epidemic model." Electronic Journal of Qualitative Theory of Differential Equations, no. 20 (2022): 1–19. http://dx.doi.org/10.14232/ejqtde.2022.1.20.

Повний текст джерела

Анотація:

It is our purpose in this paper to make a detailed description for the structure of the set of the nonconstant steady states for the two-dimensional epidemic S-I model with diffusion incorporating demographic and epidemiological processes with zero-flux boundary conditions. We first study the conditions of diffusion-driven instability occurrence, which induces spatial inhomogeneous patterns. The results will extend to the derivative of prey's functional response with prey is positive. Moreover, we establish the local and global structure of nonconstant positive steady state solutions. A priori estimates for steady state solutions will play a key role in the proof. Our results indicate that the diffusion has a great influence on the spread of the epidemic and extend well the finding of spatiotemporal dynamics in the epidemic model.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Hu, Longhua, Anthony G. Vecchiarelli, Kiyoshi Mizuuchi, Keir C. Neuman, and Jian Liu. "Directed and persistent movement arises from mechanochemistry of the ParA/ParB system." Proceedings of the National Academy of Sciences 112, no. 51 (December 8, 2015): E7055—E7064. http://dx.doi.org/10.1073/pnas.1505147112.

Повний текст джерела

Анотація:

The segregation of DNA before cell division is essential for faithful genetic inheritance. In many bacteria, segregation of low-copy number plasmids involves an active partition system composed of a nonspecific DNA-binding ATPase, ParA, and its stimulator protein ParB. The ParA/ParB system drives directed and persistent movement of DNA cargo both in vivo and in vitro. Filament-based models akin to actin/microtubule-driven motility were proposed for plasmid segregation mediated by ParA. Recent experiments challenge this view and suggest that ParA/ParB system motility is driven by a diffusion ratchet mechanism in which ParB-coated plasmid both creates and follows a ParA gradient on the nucleoid surface. However, the detailed mechanism of ParA/ParB-mediated directed and persistent movement remains unknown. Here, we develop a theoretical model describing ParA/ParB-mediated motility. We show that the ParA/ParB system can work as a Brownian ratchet, which effectively couples the ATPase-dependent cycling of ParA–nucleoid affinity to the motion of the ParB-bound cargo. Paradoxically, this resulting processive motion relies on quenching diffusive plasmid motion through a large number of transient ParA/ParB-mediated tethers to the nucleoid surface. Our work thus sheds light on an emergent phenomenon in which nonmotor proteins work collectively via mechanochemical coupling to propel cargos—an ingenious solution shaped by evolution to cope with the lack of processive motor proteins in bacteria.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Jackisch, Conrad, and Erwin Zehe. "Ecohydrological particle model based on representative domains." Hydrology and Earth System Sciences 22, no. 7 (July 6, 2018): 3639–62. http://dx.doi.org/10.5194/hess-22-3639-2018.

Повний текст джерела

Анотація:

Abstract. Non-uniform infiltration and subsurface flow in structured soils is observed in most natural settings. It arises from imperfect lateral mixing of fast advective flow in structures and diffusive flow in the soil matrix and remains one of the most challenging topics with respect to match observation and modelling of water and solutes at the plot scale. This study extends the fundamental introduction of a space domain random walk of water particles as an alternative approach to the Richards equation for diffusive flow (Zehe and Jackisch, 2016) to a stochastic–physical model framework simulating soil water flow in a representative, structured soil domain. The central objective of the proposed model is the simulation of non-uniform flow fingerprints in different ecohydrological settings and antecedent states by making maximum use of field observables for parameterisation. Avoiding non-observable parameters for macropore–matrix exchange, an energy-balance approach to govern film flow in representative flow paths is employed. We present the echoRD model (ecohydrological particle model based on representative domains) and a series of application test cases. The model proves to be a powerful alternative to existing dual-domain models, driven by experimental data and with self-controlled, dynamic macropore–matrix exchange from the topologically semi-explicitly defined structures.

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Manna, Kalyan. "Dynamics of a diffusion-driven HBV infection model with capsids and time delay." International Journal of Biomathematics 10, no. 05 (May 9, 2017): 1750062. http://dx.doi.org/10.1142/s1793524517500620.

Повний текст джерела

Анотація:

In this paper, a diffusive hepatitis B virus (HBV) infection model with a discrete time delay is presented and analyzed, where the spatial mobility of both intracellular capsid covered HBV DNA and HBV and the intracellular delay in the reproduction of infected hepatocytes are taken into account. We define the basic reproduction number [Formula: see text] that determines the dynamical behavior of the model. The local and global stability of the spatially homogeneous steady states are analyzed by using the linearization technique and the direct Lyapunov method, respectively. It is shown that the susceptible uninfected steady state is globally asymptotically stable whenever [Formula: see text] and is unstable whenever [Formula: see text]. Also, the infected steady state is globally asymptotically stable when [Formula: see text]. Finally, numerical simulations are carried out to illustrate the results obtained.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Ma, N., and J. S. Walker. "A Model of Dopant Transport During Bridgman Crystal Growth With Magnetically Damped Buoyant Convection." Journal of Heat Transfer 122, no. 1 (August 10, 1999): 159–64. http://dx.doi.org/10.1115/1.521446.

Повний текст джерела

Анотація:

This paper presents a model for the unsteady transport of a dopant during the vertical Bridgman crystal growth process with a planar crystal-melt interface and with an externally applied axial magnetic field. This dilute mass transport depends on the convective and diffusive mass transport of the dopant. The convective mass transport is driven by buoyant convection in the melt, which produces nonuniformities in the concentration in both the melt and the crystal. This convective transport is significant even for a strong magnetic field Bo=2 T. However, the electromagnetic damping of the melt motion produces a local region adjacent to the crystal-melt interface which is dominated by diffusion. Thus, this melt solidifies with a relatively radially uniform concentration, so that the radial distribution of dopants in the crystal is also relatively radially uniform. The transient model predicts the dopant distribution in the entire crystal. [S0022-1481(00)02301-X]

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Madan, Dilip B., and King Wang. "Asymmetries in financial returns." International Journal of Financial Engineering 04, no. 04 (December 2017): 1750045. http://dx.doi.org/10.1142/s2424786317500451.

Повний текст джерела

Анотація:

Market clichés assert that markets take escalators up and elevators down. The observation suggests differentiating models for up and down moves. Non-diffusive models allow for this and we model the move as the difference of two independent mean reverting increasing processes driven by gamma process shocks. The model is estimated on time series data as well as option data. Broadly speaking, the rise occurs with more frequent and smaller jumps with a faster rate of convergence to equilibrium. The down tick process has larger, less frequent moves with longer memories. Applications to delta hedging and the setting of profit targets and stop losses are also presented.

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "Driven diffusive model"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями