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191.
Jorge F. Willemsen 《Physica A》2010,389(17):3484-3495
It has been hypothesized that plankton predators sense the presence of their prey through detection of chemical signals exuded by the prey. This process is formulated using elements of existing models, tailored to correspond to the specific process under investigation. The motivation for the resulting model is discussed in detail. Numerical results are then presented. It is found that the front representing the advance of the predator into the prey is irregular in a novel way, and the reasons for this anomalous invasion are discussed. It is recognized that reaction-diffusion models, starting perhaps with Turing, can lead to what might have been thought of as anomalous patterns — yet the “flicker” front advance discovered here is indeed novel. 相似文献
192.
Claude-Michel BRAUNER Luca LORENZI Gregory I. SIVASHINSKY Chuanju XU 《数学年刊B辑(英文版)》2010,31(6):819-840
In two-dimensional free-interface problems, the front dynamics can be modeled by single parabolic equations such as the Kuramoto-Sivashinsky equation (K-S). However, away from the stability threshold, the structure of the front equation may be more involved. In this paper, a generalized K-S equation, a nonlinear wave equation with a strong damping operator, is considered. As a consequence, the associated semigroup turns out to be analytic. Asymptotic convergence to K-S is shown, while numerical results illustrate the dynamics. 相似文献
193.
194.
Nouredine Zekri Khadidja Khelloufi Lotfi Zekri Bernard Porterie Ahmed Kaiss Jean-Pierre Clerc 《Physics letters. A》2012
Non-equilibrium front propagation in a two-dimensional network modelling wildfire propagation was studied. The model includes deterministic long-range interactions due to radiation and a time weighting procedure. Three weight-dependent propagation regimes were found: dynamical, static, and non-propagative. The dynamical regime shows saturation for small weight values and a percolation transition area depending on the weight and size of the interaction domain. From the scaling interface exponents, the model seems to belong to the dynamical percolation universality class. In the limit of static regime it belongs to the random deposition class. 相似文献
195.
We are concerned with the existence of quasi-periodic solutions for the following equation
x" + Fx (x,t)x¢+ w2 x + f(x,t) = 0,x' + F_x (x,t)x' + \omega ^2 x + \phi (x,t) = 0, 相似文献
196.
Optimal variational principle for backward stochastic control systems associated with Lévy processes
The paper is concerned with optimal control of backward stochastic differential equation (BSDE) driven by Teugel’s martingales and an independent multi-dimensional Brownian motion,where Teugel’s martin- gales are a family of pairwise strongly orthonormal martingales associated with Lévy processes (see e.g.,Nualart and Schoutens’ paper in 2000).We derive the necessary and sufficient conditions for the existence of the op- timal control by means of convex variation methods and duality techniques.As an application,the optimal control problem of linear backward stochastic differential equation with a quadratic cost criteria (or backward linear-quadratic problem,or BLQ problem for short) is discussed and characterized by a stochastic Hamilton system. 相似文献
197.
198.
采用粒子模拟方法,研究沿背景磁场方向传播的低频Alfvén波对磁化等离子体加热的物理过程.模拟结果表明:离子在垂直和平行于背景磁场的方向都得到明显的加热,在非共振加热阶段,垂直方向比平行方向的加热效果更加显著,形成温度各向异性;在随机加热阶段,垂直和平行方向的温度最终达到饱和且趋于一致.加热过程中,离子所获得动力学温度的最大值由外加磁场能量密度与等离子体密度的比值决定,与Alfvén波的频率及振幅无关;离子在平行于背景磁场方向上被加速,并最终获得相当于Alfvén波相速度大小的流速. 相似文献
199.
讨论了一类广义Liénard型系统.x=p(y)k(x),.y=-f(x,y)p(y)q(y)-g(x)h(y)非零周期解的存在性和不存在性,给出了非零周期解的存在和不存在的一类充分条件. 相似文献
200.
胡世培 《数学的实践与认识》2017,(12):249-255
讨论由Brownian运动和Lévy过程共同驱动的线性随机系统的随机LQ问题,其中代价泛函是关于Lévy过程生成的σ-代数取条件期望.得到由Lévy过程驱动的新的多维的倒向随机Riccati方程,利用Bellman拟线性原理和单调收敛方法证明了此随机Riccati方程的解的存在性. 相似文献
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