The generalization of combination– combination (C–C) synchronization of chaotic n-dimensional (nD) fractional-order (0 α ≤ 1) dynamical systems is studied. Firstly, we replace arbitrary four chaotic nD ordinary dynamical systems by four chaotic nD fractional-order dynamical systems which have unique solutions. Secondly, we extend the scheme of a recent paper (Sun et al. in Nonlinear Dyn 73: 1211–1222, 2013) to study the generalization of C–C synchronization among four nDfractionalorder dynamical systems. Examples of combination– combination synchronization among four identical or different of 6D chaotic fractional-order systems are discussed. The analytical formula of the control functions is tested numerically to achieve C–C synchronization, and good agreement is found

The aim of this paper is to introduce and analyze chaotic and hyperchaotic conservative complex nonlinear systems. These systems appear in several branches of applied sciences. Lyapunov exponents are calculated to observe chaotic and hyperchaotic behaviors. The wide range of systems parameters at which chaotic and hyperchaotic solutions exist is calculated. The modules for complex variables are computed and plotted. The projections of chaotic and hyperchaotic solutions are shown in 3- spaces and 2-planes. The systems of this paper leave rooms for further studies in the near future, e.g. control and several types of synchronization of the solutions of these systems.

The aim of this paper is to introduce and analyze chaotic and hyperchaotic conservative complex nonlinear systems. These systems appear in several branches of applied sciences. Lyapunov exponents are calculated to observe chaotic and hyperchaotic behaviors. The wide range of systems parameters at which chaotic and hyperchaotic solutions exist is calculated. The modules for complex variables are computed and plotted. The projections of chaotic and hyperchaotic solutions are shown in 3- spaces and 2-planes. The systems of this paper leave rooms for further studies in the near future, e.g. control and several types of synchronization of the solutions of these systems.

MHD mixed convection of Cu-water nanofluid in a two- sided lid -driven porous cavity with a partial slip is investigated

The effect of an inclined magnetic field on the mixed convection flow in a trapezoidal cavity is investicated

The aim of this paper is to introduce a generalized form of the Lorenz system with time delay. Instead of considering each state variable of the Lorenz system belonging to R, the paper considers two of them belonging to Rn. Hence the Lorenz system has (2n + 1) dimension. This system appears in several applied sciences such as engineering, physics and networks. The stability of the trivial and nontrivial fixed points and the existence of Hopf bifurcations are studied analytically. Using the normal form theory and center manifold argument, the direction and the stability of the bifurcating periodic solutions are determined. Finally, numerical simulations are calculated to confirm our theoretical results. The paper concludes that the dynamics of this system are rich. Additionally, the values of the delay parameter at which chaotic and hyperchaotic solutions exist for different values of n using Lyapunov exponents and Kolmogorov-Sinai entropy are calculated numerically.

The passivity theory is used to achieve projective synchronization in coupled partially linear complex-variable systems with known parameters. By using this theory, the control law is thus adopted to make state vectors asymptotically synchronized up to a desired scaling factor. This paper deals with sending different large messages which include image and voice signals. The theoretical foundation of the projective synchronization based on the passivity theory is exploited for application to secure communications. The numerical simulations of secure communication are used to send large message,an image and sound (voice) signal. The errors are controlled to zero that show the agreement between theoretical and numerical simulations results.

MHD mixed convection of localized heat source/ sink in a nanofluid- filled lid- driven square cavity with partial slip is investigated

Groundwater is a major water resource in Assiut governorate. Vulnerability assessment to delineate areas that are more susceptible to contamination from anthropogenic sources has become an important element for sensible water resources management and land use planning. Potential contamination of groundwater at any specified location depends upon several physical and environmental factors, such as depth to groundwater, soil type, groundwater recharge and of course aquifer composition. Few attempts have been made to assess the potential of groundwater contamination at the Nile Aquifer at Assiut governorate, however, these attempts focused on local, or site by site basis. This contribution aims at estimating a regional groundwater vulnerability assessment for the Nile Valley aquifer in Assiut governorate by applying DRASTIC model along with GIS (ArcMap 10.x) as an effective method for groundwater pollution risk assessment. The GIS technique has provided efficient environment for analyses and high capabilities of handling large spatial data and overlaying several thematic map layers. DRASTIC is an acronym for seven variables that control the groundwater contamination potential (Depth to water, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadoze zone, and Conductivity of the aquifer) designed for characterizing the hydrogeological setting and evaluating aquifer vulnerability. This approach allowed investigating the potential of groundwater pollution on a regional scale of the study area. Using the variables given in the DRASTIC model, successive GIS-theme maps were developed describing the geometry of the area as well as the groundwater quality. These map layers were then combined in GIS to formulate the final groundwater pollution potential map. Some parts of the Nile Aquifer at Assiut governorate were dominated by “High” vulnerability classes, especially within the urban areas and settlements, while other parts were characterized by “Moderate” vulnerability classes. The elevated desert fringes of the study area obviously displayed “Low” aquifer vulnerability.

Groundwater resources in coastal aquifers constitute a main source of freshwater in many regions around the globe. This is typically true in arid and semi-arid regions where rainfall is scarce and infrequent and the surface water resources are almost absent. The consequences of climate changes and global warming on the freshwater in coastal aquifers have been investigated by several researchers over the last two decades. Due to the expected increase in the global temperature and the associated expansion of water in