Turing instability for a attraction-repolsion chemotaxis system with logistic growth
OMA-Vol. 4 (2020), Issue 1, pp. 98 – 118 Open Access Full-Text PDF
Abdelhakam Hassan Mohammed, Shengmao Fu
Abstract: In this paper, we investigate the nonlinear dynamics for an attraction-repulsion chemotaxis Keller-Segel model with logistic source term
\(u_{1t}=d_{1}\Delta{u_{1}}-\chi \nabla (u_{1}\nabla{u_{2}})+ \xi{ \nabla (u_{1}\nabla{u_{3}})}+\mathbf g(u),{\mathbf x}\in\mathbb{T}^{d}, t>0,\)
\( u_{2t}=d_{2}\Delta{u_{2}}+\alpha u_{1}-\beta u_{2},{\mathbf x}\in\mathbb{T}^{d}, t>0,\)
\(u_{3t}=d_{3}\Delta{u_{3}}+\gamma u_{1}- \eta u_{3},{\mathbf x}\in\mathbb{T}^{d}, t>0,\)
\( \frac{\partial{u_{1}}}{\partial{x_{i}}}=\frac{\partial{u_{2}}}{\partial{x_{i}}}=\frac{\partial{u_{3}}}{\partial{x_{i}}}=0,x_{i}=0,\pi, 1\leq i\leq d,\)
\( u_{1}(x,0)=u_{10}(x), u_{2}(x,0)=u_{20}(x), u_{3}(x,0)=u_{30}(x), {\mathbf x}\in\mathbb{T}^{d} (d=1,2,3).\)
Under the assumptions of the unequal diffusion coefficients, the conditions of chemotaxis-driven instability are given in a \(d\)-dimensional box \(\mathbb{T}^{d}=(0,\pi)^{d} (d=1,2,3)\). It is proved that in the condition of the unique positive constant equilibrium point \({\mathbf w_{c}}=(u_{1c},u_{2c},u_{3c})\) of above model is nonlinearly unstable. Moreover, our results provide a quantitative characterization for the early-stage pattern formation in the model.
\(u_{1t}=d_{1}\Delta{u_{1}}-\chi \nabla (u_{1}\nabla{u_{2}})+ \xi{ \nabla (u_{1}\nabla{u_{3}})}+\mathbf g(u),{\mathbf x}\in\mathbb{T}^{d}, t>0,\)
\( u_{2t}=d_{2}\Delta{u_{2}}+\alpha u_{1}-\beta u_{2},{\mathbf x}\in\mathbb{T}^{d}, t>0,\)
\(u_{3t}=d_{3}\Delta{u_{3}}+\gamma u_{1}- \eta u_{3},{\mathbf x}\in\mathbb{T}^{d}, t>0,\)
\( \frac{\partial{u_{1}}}{\partial{x_{i}}}=\frac{\partial{u_{2}}}{\partial{x_{i}}}=\frac{\partial{u_{3}}}{\partial{x_{i}}}=0,x_{i}=0,\pi, 1\leq i\leq d,\)
\( u_{1}(x,0)=u_{10}(x), u_{2}(x,0)=u_{20}(x), u_{3}(x,0)=u_{30}(x), {\mathbf x}\in\mathbb{T}^{d} (d=1,2,3).\)
Under the assumptions of the unequal diffusion coefficients, the conditions of chemotaxis-driven instability are given in a \(d\)-dimensional box \(\mathbb{T}^{d}=(0,\pi)^{d} (d=1,2,3)\). It is proved that in the condition of the unique positive constant equilibrium point \({\mathbf w_{c}}=(u_{1c},u_{2c},u_{3c})\) of above model is nonlinearly unstable. Moreover, our results provide a quantitative characterization for the early-stage pattern formation in the model.
Modeling the movement of particles in tilings by Markov chains
OMA-Vol. 4 (2020), Issue 1, pp. 84 – 97 Open Access Full-Text PDF
Zirhumanana Balike, Arne Ring, Meseyeki Saiguran
Abstract: This paper studies the movement of a molecule in two types of cell complexes: the square tiling and the hexagonal one. This movement from a cell \(i\) to a cell \(j\) is referred to as an homogeneous Markov chain. States with the same stochastic behavior are grouped together using symmetries of states deduced from groups acting on the cellular complexes. This technique of lumpability is effective in forming new chains from the old ones without losing the primitive properties and simplifying tedious calculations. Numerical simulations are performed using R software to determine the impact of the shape of the tiling and other parameters on the achievement of the equilibrium. We start from small square tiling to small hexagonal tiling before comparing the results obtained for each of them. In this paper, only continuous Markov chains are considered. In each tiling, the molecule is supposed to leave the central cell and move into the surrounding cells.
Exponential growth of solution with \(L_p\)-norm for class of non-linear viscoelastic wave equation with distributed delay term for large initial data
OMA-Vol. 4 (2020), Issue 1, pp. 76 – 83 Open Access Full-Text PDF
Abdelbaki Choucha, Djamel Ouchenane, Khaled Zennir
Abstract: In this work, we are concerned with a problem for a viscoelastic wave equation with strong damping, nonlinear source and distributed delay terms. We show the exponential growth of solution with \(L_{p}\)-norm, i.e., \(\lim\limits_{t\rightarrow \infty}\Vert u\Vert_p^p \rightarrow \infty\).
Mathematical model for measles disease with control on the susceptible and exposed compartments
OMA-Vol. 4 (2020), Issue 1, pp. 60 – 75 Open Access Full-Text PDF
Samuel O. Sowole, Abdullahi Ibrahim, Daouda Sangare, Ahmed O. Lukman
Abstract: In this paper, we develop a mathematical deterministic modeling approach to model measles disease by using the data pertinent to Nigeria. Control measure was introduced into the susceptible and exposed classes to study the prevalence and control of the measles disease. We established the existence and uniqueness of the solution to the model. From the simulation results, it was realized that the control introduced on the susceptible class; and exposed individuals at latent period play a significant role in controlling the disease. Furthermore, it is recognized that if more people in the susceptible class get immunization and the exposed people at latent period goes for treatment and therapy during this state before they become infective, the disease will be eradicated more quickly with time.
Optimal polynomial decay for a coupled system of wave with past history
OMA-Vol. 4 (2020), Issue 1, pp. 49 – 59 Open Access Full-Text PDF
S. M. S. Cordeiro, R. F. C. Lobato, C. A. Raposo
Abstract: This work deals with a coupled system of wave with past history effective just in one of the equations. We show that the dissipation given by the memory effect is not strong enough to produce exponential decay. On the other hand, we show that the solution of this system decays polynomially with rate \(t^{-\frac{1}{2}}\). Moreover by recent result due to A. Borichev and Y. Tomilov, we show that the rate is optimal. To the best of our knowledge, there is no result for optimal rate of polynomial decay for coupled wave systems with memory in the previous literature.
Linear differential equations with fast growing coefficients in the unit disc
OMA-Vol. 4 (2020), Issue 1, pp. 38 – 48 Open Access Full-Text PDF
Benharrat Belaïdi, Mohamed Amine Zemirni
Abstract: In this article, we give new conditions on the fast growing analytic coefficients of linear complex differential equations to estimate the iterated \(p\)-order and iterated \(p\)-type of all solutions in the unit disc \(\mathbb{D}\), where \(p\in \mathbb{N}\backslash \{1\}\).
Analysis and numeric of mixed approach for frictional contact problem in electro-elasticity
OMA-Vol. 4 (2020), Issue 1, pp. 20 – 37 Open Access Full-Text PDF
M. Bouallala, EL-H. Essoufi A. Zafrar
Abstract: This work handle a mathematical model describing the process of contact between a piezoelectric body and rigid foundation. The behavior of the material is modeled with a electro-elastic constitutive law. The contact is formulated by Signorini conditions and Coulomb friction. A new decoupled mixed variational formulation is stated. Existence and uniqueness of the solution are proved using elements of the saddle point theory and a fixed point technique. To show the efficiency of our approach, we present a decomposition iterative method and its convergence is proved and some numerical tests are presented.
Study of asymptotic behavior of solutions of neutral mixed type difference equations
OMA-Vol. 4 (2020), Issue 1, pp. 11 – 19 Open Access Full-Text PDF
Manel Gouasmia, Abdelouaheb Ardjouni, Ahcene Djoudi
Abstract: In this paper, we consider a neutral mixed type difference equation, and obtain explicitly sufficient conditions for asymptotic behavior of solutions. A necessary condition is provided as well. An example is given to illustrate our main results.
On a hyper-singular equation
OMA-Vol. 4 (2020), Issue 1, pp. 8 – 10 Open Access Full-Text PDF
Alexander G. Ramm
Abstract: The equation \(v=v_0+\int_0^t(t-s)^{\lambda -1}v(s)ds\) is considered, \(\lambda\neq 0,-1,-2…\) and \(v_0\) is a smooth function rapidly decaying with all its derivatives. It is proved that the solution to this equation does exist, is unique and is smoother than the singular function \(t^{-\frac 5 4}\).
A unified integral operator and further its consequences
OMA-Vol. 4 (2020), Issue 1, pp. 1 – 7 Open Access Full-Text PDF
Ghulam Farid
Abstract: The aim of this paper is to construct left sided and right sided integral operators in a unified form. These integral operators produce various well known integral operators in the theory of fractional calculus. Formulated integral operators of this study include generalized fractional integral operators of Riemann-Liouville type and operators containing Mittag-Leffler functions in their kernels. Also boundedness of all these fractional integral operators is derived from the boundedness of unified integral operators. The existence of new integral operators may have useful consequences in applied sciences besides in fractional calculus.