Abstract We examine the qualitative behaviour of an NPZ (nutrient-phyto- plankton-zooplankton) model for parameter ranges consistent with values used in literature. The wide range partly reflects variations conditions different environtments plankton, but many cases is a measure difficulties making observations and consequent uncertainties. pay particular attention to bifurcational system, regions space which oscillatory possible; such has recently been found both observational data more...

In a recent paper we proposed simple ODE model for the behaviour of populations phytoplankton and zooplankton which had mathematical structure analogous to models excitable media. That comprised two-component system, in limiting effects on growth rate such as nutrient shortage self-shading were represented parametrically. Here, demonstrate relationship system general class three-component is more realistically regarded third evolving variable, included modulation. We derive conditions...

AbstractA simple dynamical system that models the competitive thermokinetics and chemistry of cellulose decomposition is examined, with reference to evidence from experimental studies indicating char formation a low activation energy exothermal process volatilization high endothermal process. The thermohydrolysis at core primary competition described. Essentially, between two nucleophiles, molecule water an −OH group on C6 end glucosyl cation, form either reducing chain fragment propensity...

A continuing frustration for origin of life scientists is that abiotic and, by extension, pre-biotic attempts to develop self-sustaining, evolving molecular systems tend produce more dead-end substances than macromolecular products with the necessary potential biostructure and function - so-called 'tar problem'. Nevertheless primordial somehow emerged despite presumed handicap. resolution this problem important in emergence-of-life science because it would provide valuable guidance choosing...

We consider a system of partial differential equations describing two spatially distributed populations in ``predator-prey'' interaction with each other. The spatial evolution is governed by three processes: positive taxis predators up the gradient prey (pursuit), negative down (evasion), and diffusion resulting from random motion both species. demonstrate new type propagating wave this system. mechanism propagation these waves essentially depends on entirely different reaction-diffusion...

We report on a set of turbulent flow experiments the Taylor type in which fluid is contained between rotating inner circular cylinder and fixed concentric outer cylinder, focusing our attention very large number values, i.e. \[ 10^3 \leqslant T/T_c 10^5, \] where T c critical value for onset vortices. At such values , vortex structure similar to one observed when – small this apparently insensitive further increases . These flows are characterized by two widely separated length scales: scale...

Research on spatially extended excitable systems with cross-diffusion components is reviewed. Particular attention given to the new phenomena of quasi-soliton and half-soliton interaction excitation waves, which are specific such occur along standard nonsoliton wave that causes waves mutually annihilate. A correlation shown exist between regimes profile shapes. One example a system population taxes. Based mathematical models experimental work bacterial populations, in can be identified as...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReduced Mechanisms for Propane PyrolysisAlison S. Tomlin, Michael J. Pilling, John H. Merkin, Brindley, Neill Burgess, and Arthur GoughCite this: Ind. Eng. Chem. Res. 1995, 34, 11, 3749–3760Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://pubs.acs.org/doi/10.1021/ie00038a010https://doi.org/10.1021/ie00038a010research-articleACS PublicationsRequest reuse...

A simple mathematical model is constructed to describe the regime of flow, extending over a wide range values Taylor number, in which turbulent Taylor–Couette flow annular region between two coaxial circular cylinders characterized by coexistence steady coherent motion on widely separated scales. These scales motion, corresponding gap width and boundary-layer thickness, are each identified as consequence centrifugal instability, described vortices Görtler respectively. The assumption that...

We consider a spatially distributed population dynamics model with excitable predator-prey dynamics, where species propagate in space due to their taxis respect each other's gradient addition to, or instead of, diffusive spread. Earlier, we have described new phenomena this one spatial dimension, not found analogous systems without taxis: reflecting and self-splitting waves. Here identify two dimensions: unusual patterns of meander spirals, partial reflection waves, swelling wavetips,...

A simple model for the thermal decomposition of amorphous cellulose is proposed that rationalizes effect water in promoting charring process at expense volatilization. Simulations mass-loss histories and product evolution are shown to be consistent with various experimental observations literature. Under char-promoting conditions where heat transfer limited, anomalous effects predicted which indicate char formation may not always desirable fire-inhibiting treatments or strategies cellulosic...

We present an analysis of instability to transverse perturbations laminar premixed plane spray flames. To this end, a thermal‐diffusional model flame front propagating through overall fuel‐rich or fuel‐lean droplet‐vapour‐air mixture is presented. The fuel droplets are permitted vaporize at finite rate so that their interaction with, and possible traversal of, the accounted for. After establishing steady‐state solutions by means high activation energy asymptotics, detailed linear stability...

Abstract The effect of environmental variability on fish recruitment is analysed using simple linear growth models. It shown that variance in an individual's environment significantly increases the probability recruitment. also argued should lead to differences rates observed recruited fish, and mean rate overall population. These conclusions are discussed with reference recent observations from field studies.

Evolution equations are developed for weakly nonlinear baroclinic wave packets in a flow with continuous shear and stratification. When dispersion is forced by using sloping upper lower boundaries it shown that, boundary slope equal to isothermal the basic state, these evolution transformable sine-Gordon equation. The relation between behaviour this model that discretelayer models of instability discussed, finally solutions equation appropriate periodic domain presented compared experimental results.

We consider travelling wave solutions of a reaction–diffusion system corresponding to single-step homogeneous premixed combustion scheme competitively coupled with an endothermic reaction. Properties the reaction fronts, such as speed and burnt temperature are derived numerically over range different parameter values, those describing relative enthalpies, rates activation energies exothermic reactions. Unique shown exist for each distinct combination values. Stability analyses using both...

An attempt is made to find a theoretical explanation for the type of flow observed when liquid subjected at same time rotation and horizontal temperature gradient. W hen contained between two concentric cylinders it known from experiment that distinct types occur, one in which motion form meridional vortex with addition zonal component, other exhibits meandering wave-like pattern. Of vital importance as regards found be parameter defined Rossby number problem, sets critical values this are...