Volume 23, Issue 6

Recently, propagation models of worms in the mobile environment are drawing extensive attention, particularly in the Wi-Fi scenario. Considering that worm-free equilibrium is exponential convergent means that the propagation time and control time of worms are much shorter than for other asymptotic convergence. Besides, the global asymptotic stability of the endemic equilibrium is more important than the local asymptotic stability, which reflects the more global qualitative behavior of the worm propagation. In this paper, we discuss the global dynamics of SEIQR worm propagation model in mobile internet proposed by Xiao et al. [X. Xiao, P. Fu, C. Dou, Q. Li, G. Hu, and S. Xia, “Design and analysis of SEIQR worm propagation model in mobile internet,” Commun. Nonlinear Sci. Numer. Simulat., vol. 43, pp. 341–350, 2017] to improve and complement the related results. Through a series of mathematical derivations, sufficient conditions are derived to ensure the global exponentially stability of worm-free equilibrium, and the exponential convergent rate can be unveiled. Then, by using the classical geometric approach, it is shown that the endemic equilibrium is globally asymptotically stable and the system is persistent when R 0 > 1. Moreover, numerical simulations are given to demonstrate our theoretical results.

The dump flooding technology comes from offshore oil fields. It is necessary to increase the production of oil by water injection when fracture-cavity reservoirs in Xinjiang enter their middle and later stages. Lack of water sources in the desert area and the presence of heavy upper water layers encourage further research into the application of this technology. The dump flooding technology can eliminate the need for specialized injection wells and reduce the consumption of oil fields in the surface water sources, which may significantly aid in the development of the local economy and environment. In China, the research on dump flooding is still in its preliminary phase. Hence, there is no complete flow model for gravity flow and no optimization design software to optimize the development effect. This article sets up a flow model of a water layer-well-fracture unit by key local nodes. The key nodes, such as some perforating water layer, the bullet hole or the water valve, were simulated using the COMSOL software. The flow equations of each node were coupled together for the system-wide flow coupling model to verify the whole system by the numerical simulation, which needs Eclipse to run. The results of the research can be used to predict the water injection rates and formation pressures, and also provide a reference and a basis for the optimal design of water injection.

In the present work, the exp(− φ ( ξ ))-expansion method is applied for solving the deterministic and stochastic Phi-4 equation. Namely, we introduce hyperbolic, trigonometric, and rational function solutions. The computational study shows that the offered method is pretentious, robust, and influential in applications of interesting analysis, observations of particle physics, plasma physics, quantum field theory, and fluid dynamics. The control on the randomness input (the coefficients are random variables) is studied in order to obtain stability stochastic process solution with beta distribution. In this work, we will deal with stability moment method and then we apply the mean square calculus for the stability concept.

In this paper, an investigation is conducted in order to understand impacts of Particle Swarm Optimization (PSO) parameters on the convergence and the quality of the inverse kinematics solutions provided by the IK-PSO (inverse kinematics solver using PSO) – a heuristic inverse kinematics solver algorithm. Over a large panel of parameters investigations, a statistical proof of convergence is provided for 5 links to 60 links articulated system. A recommended set of parameters intervals are presented for this class of IK problems. Investigations are based on the standard inertia weight PSO, and concerned the impact of the inertia weight, the swarm size and the maximum iteration number. For a given set of parameters, the existence of a solution with a given position error is also proved. All tests were conducted over 100 times. The density of probability function, PDF, is used to approximate and analyze the fineness functions, which are the square of the position error. Results showed IK-PSO is an interesting IK solver when a set of good parameters are used. For these parameters, the algorithm showed a statistical proof of convergence with a high resolution, by mean of error position. The algorithm also showed time-effectiveness compared to CCD method, which is assumed to be a real-time IK heuristic solver used in gaming.

In this paper, we studied the separability of the non-linear Schrodinger operator of the form S u x = − Δ u x + V x , u u x ,  where  Δ u x = ∑ i = 1 n ∂ 2 u x ∂ x i 2 , $Su\left(x\right)=-{\Delta}u\left(x\right)+V\left(x,u\right)u\left(x\right),\hspace{0.17em}\text{where}\hspace{0.17em}{\Delta}u\left(x\right)={\sum }_{i=1}^{n}\frac{{\partial }^{2}u\left(x\right)}{\partial {x}_{i}^{2}},$ with the non-linear matrix potential V x , u $V\left(x,u\right)$ . We obtained the sufficient conditions for separability of this operator in the space L 2 R n ℓ ${L}_{2}{\left({R}^{n}\right)}^{\ell }$ and we established the suitable coercive inequalities.

In this paper, the general decay projective synchronization of a class of memristive competitive neural networks with time delay is studied. Firstly, a nonlinear feedback controller is designed, which does not require any knowledge about the activation functions. Then, some new and applicable conditions dependent on the Lyapunov function and the inequality techniques are obtained to guarantee the general decay projective synchronization of the considered systems under the developed controller. Unlike other forms of synchronization, projective synchronization can improve communication security due to the scaling constant’s unpredictability. In addition, the polynomial synchronization, asymptotical synchronization, and exponential synchronization can be seen as the special cases of the general decay projective synchronization. Finally, a numerical example is given to demonstrate the effectiveness of the proposed control scheme.

We are concerned with the vanishing flux-approximation limits of solutions to the isentropic relativistic Euler equations governing isothermal perfect fluid flows. The Riemann problem with a two-parameter flux approximation including pressure term is first solved. Then, we study the limits of solutions when the pressure and two-parameter flux approximation vanish, respectively. It is shown that, any two-shock-wave Riemann solution converges to a delta-shock solution of the pressureless relativistic Euler equations, and the intermediate density between these two shocks tends to a weighted δ -measure that forms a delta shock wave. By contract, any two-rarefaction-wave solution tends to a two-contact-discontinuity solution of the pressureless relativistic Euler equations, and the intermediate state in between tends to a vacuum state.

In view of the poor thermodynamic environment problem of the self-powered launch of land-based concentric canister launcher (CCL), the launching scheme of injecting water at the bottom of launching tube is adopted to improve the thermodynamic environment of the launching system fundamentally. The solution program for liquid water vaporization is compiled and embedded into the homogeneous gas–liquid two-phase flow model, the source phase corrections of the momentum equation and the energy equation are also performed, and then the three-dimensional gas–liquid two-phase fluid dynamics model is established for the land-based CCL; analysis shows that the improvement of the thermal environment of the 35° and 45° water injection schemes is more better among these schemes. So coupling the mixture model, vaporization program and FW–H (Ffowcs Williams Hawkings) noise model, the noise distribution law in the bottom of the launcher cube for 35 and 45 water injection angles is discussed; in the intermediate frequency range, the −45° water injection scheme is about 2–10 dB higher than the noise signal of the −30° water injection scheme. Finally, it is recommended to optimize the overall thermal environment of the CCL by using the −30° preferred water injection scheme with both cooling effect and noise control.

Hypoxy induced angiogenesis processes can be described by coupling an integrodifferential kinetic equation of Fokker–Planck type with a diffusion equation for the angiogenic factor. We propose high order positivity preserving schemes to approximate the marginal tip density by combining an asymptotic reduction with weighted essentially non oscillatory and strong stability preserving time discretization. We capture soliton-like solutions representing blood vessel formation and spread towards hypoxic regions.

The study of the thermal inertia of buildings is a subject of major interest. The thermal insulation and the nature of the wall sensitively modify the inertia of the building and are the solutions to improve the energy efficiency of the envelope. The roof is well exposed to solar radiation in summer and contributes to significant losses in winter due to convective exchanges. To lead to a thermal comfort, a thermal insulation is necessary. In this context, we carry out a numerical study of the thermal behavior of a building with two zones in variable meteorological conditions for a Tunisian climate (region of Sousse) based on the thermoelectric analogy and using the nodal method as a numerical method. The object of this work is to study the effect of the thermal inertia of the roof equipped with a multi-alveolar structure on the thermal behavior of the air inside the room and on its energy consumption. Taking into account the energy input of occupant, a complete model was established to increase the accuracy of the calculations. The results show that the multi-alveolar structure placed on the outside of the roof reduces energy consumption during the winter period when the alveolar structure is placed in the conductive direction and during the summer period when the alveolar structure is placed in the insulate direction.