Periodic solution of a pest management Gompertz model with impulsive state feedback control

In this paper, a new model with two state impulses is proposed for pest management. According to different thresholds, an integrated strategy of pest management is considered, that is to say if the density of the pest population reaches the lower threshold \(h_1\) at which pests cause slight damage to the forest, biological control (releasing natural enemy) will be taken to control pests; while if the density of the pest population reaches the higher threshold \(h_2\) at which pests cause serious damage to the forest, both chemical control (spraying pesticide) and biological control (releasing natural enemy) will be taken at the same time. For the model, firstly, we qualitatively analyse its singularity. Then, we investigate the existence of periodic solution by successor functions and Poincaré-Bendixson theorem and the stability of periodic solution by the stability theorem for periodic solutions of impulsive differential equations. Lastly, we use numerical simulations to illustrate our theoretical results.     

Bifurcations of limit cycles for a cubic Hamiltonian system under quartic perturbations

This paper is concerned with the number of limit cycles of a cubic system with quartic perturbations. Fifteen limit cycles are found and their distributions are studied by using the methods of bifurcation theory and qualitative analysis. It gives rise to the conclusion: H(4)15, where H(n) is the Hilbert number for the second part of Hilbert's 16th problem.     

Pore-Scale Simulation of Fluid Flow Through Deformable Porous Media Using Immersed Boundary Coupled Lattice Boltzmann Method

Transport in Porous Media - The interaction between the fluid flow and the deformable porous media is crucial in the applications of adsorption/absorption. The immersed boundary coupled lattice...     

Speckle noise reduction in digital holography with spatial light modulator and nonlocal means algorithm

An integrated method based on optical and digital image processing is presented to suppress speckle in digital holography. A spatial light modulator is adopted to introduce random phases to the illuminating beam. Multiple holograms are reconstructed and superimposed, and the intensity is averaged to smooth the noise. The adaptive algorithm based on the nonlocal means is designed to further suppress the speckle. The presented method is compared with other methods reduction is improved, and the proposed method is effective The experimental results show that speckle and feasible.     

Some new results for a logistic almost periodic system with infinite delay and discrete delay

A nonautonomous logistic almost periodic system with infinite delay and discrete delay is considered. Our result shows that the system is globally asymptotically stable under the condition for the boundedness of the system. By using almost periodic functional Hull theory and new computational techniques, we show that the almost periodic system has a unique globally asymptotically stable strictly positive almost periodic solution under the condition for the boundedness of the system. Some recent results are improved, and an open question is answered.     

种群模型在生物进化研究中的应用

介绍了进化动力学的基本知识和研究现状,把表型特征引入种群动力学模型,进而推导出进化适应动力学模型;总结了如何建立适应度函数以及分析研究进化动力学行为的一般理论和方法,并列举实例,模拟分析验证前面所陈述的理论方法,模拟结果说明收获对生物进化产生重要影响,并有效解释了物种多样性。     

The dynamics of a mutual interference age structured predator-prey model with time delay and impulsive perturbations on predators

In this paper, we introduce a mutual interference age structured predator-prey (natural enemy-pest) model with constant maturation time delay for the prey, and then propose a pest management strategy by constant periodic releasing for the predator. We show that there exists a global attractive pest-eradication periodic solution when the periodic releasing amount μ₁ and μ₂ are lager than some critical value. Further, to obtain a more effective pest control strategy, we give the conditions (involving the estimate of μ₁ and μ₂) in which the model is uniformly permanent and the pest population is under the economic threshold level. We believe that the results will provide reliable tactic basis for the practical pest management.     

Wetting boundary conditions in numerical simulation of binary fluids by using phase‐field method: some comparative studies and new development

We studied several wetting boundary conditions (WBCs) in the numerical simulation of binary fluids by using phase‐field method. Five WBCs, three using the linear, cubic, and sine form surface energy (LinSE, CubSE, and SinSE), the other two using the geometric formulation (Geom) and the characteristic interpolation (CI), were compared through the study of several problems: (1) the static contact angle (CA) of a drop; (2) a Poiseuille flow‐driven liquid column; (3) a wettability gradient (WG)‐driven liquid column; and (4) drop dewetting. It was found that while all WBCs can predict the static CA fairly accurately, they may affect the simulation outcomes of dynamic problems differently, depending on the CA. For the flow‐driven problem with a CA near 90°, using different WBCs had almost no effect on the flow characteristics over a large scale. For the WG‐driven problem, to use different WBCs may lead to different steady drop velocities, and all WBCs except LinSE can give reasonably consistent prediction between the drop velocity and dynamic CAs. For drop dewetting, Geom led to the most violent drop motion, whereas CubSE caused the weakest motion. For several problems, CubSE and SinSE gave almost the same results, and those by Geom and CI were also close, possibly due to similar consideration in their design. Besides, a new implementation that may be used for all WBCs was proposed to mimic the wall energy relaxation and control the degree of slip. This new procedure made it possible to allow the simulations to match experimental measurements well. Copyright © 2014 John Wiley & Sons, Ltd.     

New seco-dibenzocyclooctadiene lignans with nitric oxide production inhibitory activity from the roots of Kadsura longipedunculata

Four new seco-dibenzocyclooctadiene lignans,kadlongilignans A-D(1-4),consisting of a rare 6,7-seco-(1),two 15,16-seco-(2 and 3) and a 9,10-seco-dibenzocyclooctadiene(4) lignans,were isolated from the roots of Kadsura longipedunculata.Their structures were elucidated by spectroscopic analysis,including extensive NM R,MS and ECD(electronic circular dichroism) spectra.Compounds 3 and 4 exhibited potent inhibitory activities against NO(nitric oxide) production of LPS(lipopolysaccharide)-induced murine macrophages with the inhibition rates of 36.3% and 26.9%,respectively.