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Vegetation patterns can reflect vegetation's spatial distribution in space and time. The saturated water absorption effect between the soil–water and vegetation plays a crucial role in the vegetation patterns in semi-arid regions. Moreover, vegetation can absorb water through the nonlocal interaction of roots. In this paper, we consider how cross-diffusion and nonlocal delay interactions affect vegetation growth. The conditions under which the vegetation-water model generates the Turing pattern are obtained by mathematical analysis. At the same time, the multiple scales method is applied to obtain the amplitude equations at the critical value of Turing bifurcation, which helps us to derive parameter space more specifically where specific patterns such as strips, hexagons, and the mixture of strip and hexagons will emerge. Various spatial distributions of vegetation in semi-arid areas are qualitatively depicted by numerical simulations. The results show that the nonlocal delay effect enhances vegetation biomass. Therefore, we can take measures to increase the intensity of the nonlocal delay effect to increase vegetation density, which theoretically provides new guidance for vegetation protection and desertification control. • We consider a spatial vegetation system with cross-diffusion and nonlocal delay. • The nonlocal water absorption intensity can induce the phase change of vegetation pattern. • Regular spot, stripe and mixed patterns appear in the appropriate feedback intensities. [ABSTRACT FROM AUTHOR]

A long Josephson junction comprising regions with phase discontinuities driven by an external ac-drive is studied. An inhomogeneous sine-Gordon equation is used, that depicts the dynamics of long Josephson junctions with phase discontinuities. Perturbation technique along with asymptotic analysis and the method of averaging are applied to obtain an average dynamics in the form of double sine-Gordon equations for both small and large driving amplitudes. From the obtained average dynamics, it is determined that, the external ac-drive may affect the presence of the ground state of the junction. Specifically, the cases for 0 − κ and 0 − π − 0 junctions are discussed. In the presence of an external ac-drive, the critical facet length b c is analyzed for 0 − π − 0 junction above which the ground state is non-uniform. The critical bias current γ c for 0 − κ junction is investigated, at which the junction switches to a resistive state. Further, the interaction of localized defect modes and the fast oscillating drive is studied for both 0 − κ and 0 − π − 0 junctions, which is explained by using Lagrangian approach. Numerical simulations are performed to support our analytical calculations. [ABSTRACT FROM AUTHOR]

Soft materials can experience a mechanical instability when subjected to a finite compression, developing wrinkles which may eventually evolve into folds or creases. The possibility to control the wrinkling network morphology has recently found several applications in many developing fields, such as scaffolds for biomaterials, stretchable electronics and surface micro-fabrication. Albeit much is known of the pattern initiation at the linear stability order, the nonlinear effects driving the pattern selection in soft materials are still unknown. This work aims at investigating the nature of the elastic bifurcation undertaken by a growing soft layer subjected to a equi-biaxial strain. Considering a skin effect at the free surface, the instability thresholds are found to be controlled by a characteristic length, defined by the ratio between capillary energy and bulk elasticity. For the first time, a weakly nonlinear analysis of the wrinkling instability is performed here using the multiple-scale perturbation method applied to the incremental theory in finite elasticity. The Ginzburg–Landau equations are derived for different superposing linear modes. This study proves that a subcritical pitchfork bifurcation drives the observed wrinkle-to-fold transition in swelling gels experiments, favoring the emergence of hexagonal creased patterns, albeit quasi-hexagonal patterns might later emerge because of an expected symmetry break. Moreover, if the surface energy is somewhat comparable to the bulk elastic energy, it has the same stabilizing effect as for fluid instabilities, driving the formation of stable wrinkles, as observed in elastic bi-layered materials. [ABSTRACT FROM AUTHOR]

• A primary system with two unstable modes coupled to a Nonlinear Energy Sinks is studied. • We analyze the model using successively iorthogonal transformation, complexification-averaging method and eometric singular perturbation theory. • he possibility of mitigating simultaneously two unstable modes using a NES is shown. • good agreement is observed between theoretical results and numerical simulations which validates the proposed asymptotic analysis. This paper investigates a problem of passive mitigation of vibratory instabilities caused by two unstable modes by means of a single nonlinear energy sink (NES). For this purpose, a linear four-degree-of-freedom (DOF) primary structure having two unstable modes (reproducing the typical dynamic behavior of a friction system) and undergoing, as it is linear, unbounded motions when it is unstable, is coupled to a NES. In this work, the NES involves an essentially cubic restoring force and a linear damping force. We are interested in characterizing analytically the response regimes resulting from the coupling of the two unstable linear modes of the primary structure and the nonlinear mode of the NES. To this end, from a suitable rescaling of the governing equations of the coupled system in which the dynamics of the primary structure is reduced to its unstable modal coordinates, the complexification-averaging method is applied. The resulting averaged system appears to be a fast-slow system with four fast variables and two slow ones related to the two unstable modes of the primary structure. The critical manifold of the averaged dynamics is obtained through the geometric singular perturbation theory and appears as a two-dimensional parametric surface (with respect to two of the four fast variables) which evolves in the whole six-dimensional variable space. The asymptotic analysis reveals that the NES attachment can produce some bounded responses and suggests that the system may have simultaneous stable attractors. Numerical simulations complement the study, highlighting a possible competition between stable attractors and allowing us to investigate their basins of attraction. In each considered situation, a good agreement has been observed between theoretical results and numerical simulations, which validates the proposed asymptotic analysis. [ABSTRACT FROM AUTHOR]