In this article, a wideband monopole antenna with band notched reconfigurability is proposed. The antenna consists of a wideband monopole antenna, incorporated with reconfigurable electromagnetic bandgap (EBG) structures. Six EBG structures with different band notched frequency are used to achieve six band notched reconfigurations. The EBG structures are placed underneath the feed line of the antenna. A switch is placed at each EBG structure, and by controlling the state of the switch, the band notched operation of the EBG can be activated or deactivated. The proposed antenna is capable to provide useful features for the notched band UWB communication system. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:497–501, 2015

Non-Newtonian fluid model was created against the Newton’s Law of viscosity where the viscosity is no more constant and dependent on the shear rate. The existing such fluid can be found in many industrial claims especially in food manufacturing, lubrication, biomedical flows and oil and gas. Besides, the used of non-Newtonian fluid occurs in mining industry where the slurries and muds are often handled. There are many models on non-Newtonian fluid available in literature where some of them capture the specific properties. The Reiner–Philippoff (RP) fluid model is considered in this endeavour due to the capabilities of the model which can be acted in three different family of fluid which are viscous, shear thickening and the shear-thinning. Mathematical model is constructed using continuity, momentum and energy equations where in form of partial differential equations (PDEs). The complexity of the proposed model is abridged by deduced the equations into ordinary differential equations (ODEs) by adopting similarity variables before the computation is done by bvp4c function drive in MATLAB software. To ratify the validity of the proposed model as well as numerical outputs, the comparative study is performed and it found to be in very strong agreement under limiting case where the present model is condensed to be identical with the reported model previously. The consequences of pertinent parameters on fluid’s characteristics are analyzed in details through the plotted graphic visuals and tabular form.

The nonlinear density variation with temperature happens in many thermal applications like solar collectors, energy production, heat exchangers, and combustions, and it gives a significant impact on heat transfer and fluid flows. Thus, a nonlinear convective of an unsteady stagnation point flow under the influence of gravity modulation in the presence of water-based nanoparticles alumina (Al2O3) is studied here. Suitable variables are utilized to reduce the highly coupled nonlinear governing equations into a system of dimensionless simple partial differential equations. The Keller-box method is then applied to solve the consequent governing equations. Velocity and temperature profiles for various values of pertinent parameters are displayed graphically and discussed. The results indicate that the quadratic convection has enhanced the fluid flow and heat transport. Furthermore, the nonlinear convection parameter and the nanoparticles volume fractions have delivered a positive effect on the skin friction and the rate of heat transfer.

Radiation therapy is one of the cancer cells treatments that use high-energy radiation to shrink tumors and kill cancer cells. Radiation therapy kills cancer cells by damaging their DNA directly or creates charged particles within the cells that can in turn damage the DNA. As a side effect of the treatment, the radiation therapy can also damage the normal cell that located at parts of our body. The main goals of radiation therapy are to maximize the damaging of tumors cell and minimize the damage of normal tissue cell. Hence, in this study, we adopt an existing model of high dose irradiation damage. The purpose of this study is to estimate the six parameters of the model which are involved. Two optimization algorithms are used in order to estimate the parameters: Nelder-Mead (NM) simplex method and Genetic Algorithm (GA). Both methods have to achieve the objective function which is to minimize the sum of square error (SSE) between the experimental data and the simulation data. The performances of both algorithms are compared based on the computational time, number of iteration and value of sum of square error. The optimization process is carried out using MATLAB programming built-in functions. The parameters estimation results shown that Nelder-Mead simplex method is more superior compare to Genetic Algorithm for this problem.

The effectiveness of the heat transfer fluid in the cooling or heating process determines the optimal performance of the nuclear reactor, microelectronic devices, and chip production. Since thermal conductivity improved in hybrid nanofluids, the current study sought to investigate the unsteady free convection hybrid nanofluid flow near a stagnation point as influenced by g-jitter. A hybrid nanofluid consisted of copper (Cu) and alumina (Al2O3) nanoparticles, which were added into water to form Cu-Al2O3/water was considered. Next, relevant variables transformed the governing equation into dimensionless equations before being solved numerically using a centered implicit finite difference method. The fluid field and heat transfer were discussed concerning the stagnation point curvature ratio. The results showed that the g-jitter effect caused fluctuation in all profiles and physical quantities. The frequency and amplitude of the g-jitter reduced the velocity profile while improving the temperature distribution. The heat transfer rate increased by 10.77% when the hybrid nanoparticles volume fractions rose from 0.1 to 0.2. However, the presence of hybrid nanoparticles had reduced the thickness of the momentum boundary layer due to an increase in the local skin friction.