Double dispersed bioconvective Casson nanofluid fluid flow over a nonlinear convective stretching sheet in suspension of gyrotactic microorganism

Microorganisms play a vital role in understanding the ecological system. The motions of micororganisms are self‐propelled while the impact of thermophoresis and Brownian motion property of nanoparticle shows more challenges in biotechnological and medical applications. The present problem is based on the understanding of double‐dispensed bioconvection for a Casson nanofluid flow over a stretching sheet. Suction phenomenon is introduced at the surface of the stretching sheet along with the convective boundary condition. The convection and movement of the microorganisms are assisted by an applied magnetic field, nonlinear thermal radiation, and first‐order chemical reaction. The governing equations are highly coupled and thus we used the spectral quasilinearization method to solve the governing equations. The study of the residual errors on the systemic parameters had given a confidence with the present results. The final outcomes are displayed through graphs and tables. The thermal dispersion coefficient shows a positive response in the temperature while a similar response is observed for the concentration with solutal dispersion coefficient. The response is reversible for the heat transfer rate at the surface with thermal dispersion coefficient. The density of the motile microorganism at the surface decreases with increase in the Casson number, thermal dispersion coefficient, and solute dispersion coefficient, while an opposite phenomenon was observed with increase in the density ratio of the motile microorganism.     

Handover approaches for seamless mobility management in next generation wireless networks

Next generation wireless networks (NGWN) will be an integration of heterogeneous wireless access networks that will interwork over an IP‐based infrastructure. This all‐IP vision has led to the development of handover mechanisms to support seamless mobility for active network services among the different interworking wireless networks in order to ensure network access ubiquity in NGWN. These handover mechanisms need to ensure that mobile devices continue to receive ongoing communication without any noticeable disruption during handover events among the heterogeneous networks. This paper gives a qualitative and quantitative review of current handover approaches of IP mobility management protocols for NGWN with an objective to introduce a new way of further optimizing the handover performance. In particular, the paper focuses on handover approaches of mobile IPv6 (MIPv6) based mobility management protocols. Thus, the need, benefits, and limitations of these handover approaches are explored. Thereafter, dynamic handover coordination is introduced as a new viable solution that exploits the benefits and mitigates the limitations of these handover approaches hence improving handover performance in terms of handover delay, packet loss, and signaling overhead. Copyright © 2011 John Wiley & Sons, Ltd.     

Transient electromagnetohydrodynamic radiative squeezing flow between two parallel Riga plates using a spectral local linearization approach

This article addresses transient electromagnetohydrodynamic radiative squeezing flow due to convectively heated electromagnetic actuator. The transport analysis of heat and mass is explored considering the heat generation/absorption and destructive species homogeneous reaction. Suitable transformations are applied on the mathematical model developed to convert governing partial differential equations to ordinary differential equations (ODEs). Spectral local linearization method (SLLM) is employed on the resultant nonlinear coupled ODEs to compute the numerical results. Influence of sundry physical quantities on heat mass transfer of squeezing flow characteristics are determined using graphs and tabular results. SLLM results exhibit that momentum and temperature improved with rise in squeezing and heat source parameters correspondingly. Momentum enhances at lower plate and detracts with rise in modified Hartmann number. For improved heat source parameter, the rate of heat transfer diminishes and is more significant for higher Prandtl number values. This investigation has relevance in disk style magnetic clutches, rolling elements, food processing, bearings, squeezing film pressure sensors, and flow rheostats.     

Jeffrey nanofluid flow near a Riga plate: Spectral quasilinearization approach

This article attempts to report the flow mechanism of Jeffrey nanofluid flow on a Riga plate integrating the influences of viscous dissipation, irregular heat source/sink, Brownian motion, and thermophoretic force. Nondimensionalization of mathematical model describing the flow system is accomplished by a set of compatible transformations. An accurate solution of ordinary differential equations is achieved by practicing spectral quasilinearization method. The present method is capable of giving results with good accuracy in few iterations, which infers speedy convergence. Solution‐based error norm (a measure of difference of approximate solution in two consecutive iteration level) is presented to authenticate precision of obtained approximate solution. The similarity between present approximate results and previously reported results is noted to check correctness. Obtained numerical solutions were replicated in a diagrammatic form to visualize the impact of flow parameters. Ratio of relaxation to retardation time produces an enhancing influence on momentum and nanoparticle concentration and a declining effect on the fluid temperature. Riga plate strengthens the momentum, which intensifies the transport of heat energy from boundary layer region, resulting in a reduction in fluid temperature.     

Spectral local linearisation method for MHD Casson fluid on stratified bioconvective porous medium flow due to gyrotactic microorganisms

In this paper, the effect of hall parameter on the flow of Casson nanofluid containing gyrotactic microorganisms over a stretching boundary in a porous medium is studied. The stratification, porosity, and Casson fluid parameters are also examined. Using suitable similarity transformations, the basic equations describing the flow are converted to nonlinear differential equations, which are then solved computationally using the spectral local linearisation method. The effects of key parameters such as the Hall parameter, the thermophoresis parameter, the porosity parameter, and Casson fluid parameters are analyzed. The results obtained suggest that the Hall parameter has the effect of decreasing the secondary flow, the heat and mass transfer rate, and density of the motile microorganisms. A decrease in the the Hall parameter is found to cause an increase in the transfer rate, the mass transfer rate, and the density of the motile microorganisms. An increase in the porosity parameter leads to a decline in the skin friction, heat transfer rate, mass transfer rate, and density of the motile microorganisms. The applications of this study arise in industrial areas, including Hall current accelerators, planetary dynamics, Hall current sensors, and magnetohydrodynamic power generators.     

Lignocellulosic Biomass Waste-Derived Cellulose Nanocrystals and Carbon Nanomaterials: A Review

Rapid population and economic growth, excessive use of fossil fuels, and climate change have contributed to a serious turn towards environmental management and sustainability. The agricultural sector is a big contributor to (lignocellulosic) waste, which accumulates in landfills and ultimately gets burned, polluting the environment. In response to the current climate-change crisis, policymakers and researchers are, respectively, encouraging and seeking ways of creating value-added products from generated waste. Recently, agricultural waste has been regularly appearing in articles communicating the production of a range of carbon and polymeric materials worldwide. The extraction of cellulose nanocrystals (CNCs) and carbon quantum dots (CQDs) from biomass waste partially occupies some of the waste-recycling and management space. Further, the new materials generated from this waste promise to be effective and competitive in emerging markets. This short review summarizes recent work in the area of CNCs and CQDs synthesised from biomass waste. Synthesis methods, properties, and prospective application of these materials are summarized. Current challenges and the benefits of using biomass waste are also discussed.