Effect of MWCNT–Fe3O4/water hybrid nanofluid on the thermal performance of ribbed channel with apart sections of heating and cooling

Journal of Thermal Analysis and Calorimetry - A two-dimensional (2D) numerical simulation is performed to simulate the laminar forced convection of a nanofluid in a ribbed channel with apart...     

Multigrid solution of high order discretisation for three-dimensional biharmonic equation with Dirichlet boundary conditions of second kind

In this paper, we propose two compact finite difference approximations for three-dimensional biharmonic equation with Dirichlet boundary conditions of second kind. In these methods there is no need to define special formulas near the boundaries and boundary conditions are incorporated with these techniques. The unknown solution and its second derivatives are carried as unknowns at grid points. We derive second-order and fourth-order approximations on a 27 point compact stencil. Classical iteration methods such as Gauss–Seidel and SOR for solving the linear system arising from the second-order and fourth-order discretisation suffer from slow convergence. In order to overcome this problem we use multigrid method which exhibit grid-independent convergence and solve the linear system of equations in small amount of computer time. The fourth-order finite difference approximations are used to solve several test problems and produce high accurate numerical solutions.     

The daily radon dose in body organs caused by drinking milk and water

Milk is considered as the richest nutrition, being used by people. When drinking milk or water the radon gas will transfer from air to them rapidly. Since milk is majorly composed of water, probably radon existence in livestock consumable water could be the main cause of its presence in milk. Different portion of milk changed by radon gamma ray and consumption of radon included water or milk has its effects on the human body. For investigation the effect of radon in water or milk on human organs, this study has been done in two phases with MCNPX software. In the first phase, the dose rate of absorbed gamma ray by different portion of milk which is indoctrinated by 1 Bq/m³ of radon during a day is calculated. Moreover, the effects shown by milk and its components in radon gamma spectrum, which is demonstrator of milk absorption spectrum, are also surveyed. In the second phase as well, according to the human body phantom, the absorbed gamma dose caused by daily consumption of indoctrinated water or milk with 1 Bq/m³ radon is calculated. The production rate of free radicals in milk and its different components are derived according to escape data of MCNPX code.     

Temporal Evolution of Polarization Resolved Laser-Induced Breakdown Spectroscopy of Cu

Plasma Chemistry and Plasma Processing - Polarization-resolved laser-induced breakdown spectroscopy based on a temporal investigation of polarized Cu plasma emission is presented by a gated...     

Dynamic behavior of nucleation in supercritical N2 foaming of polystyrene-aluminum oxide nanocomposite

In this study, dynamic behaviour of nucleation was investigated during foaming process of polystyrene in presence of nano aluminium oxide. Nano aluminium oxide played a role of a bubble nucleating agent within polystyrene matrix. Foaming process was visually observed in conjunction with supercritical N₂. Furthermore, the effect of nano Al₂O₃ compositions on the growth rate was studied. Also, final density per unit area and the average size in the latest growth steps were assessed. The obtained data were compared with foaming process for unfilled polystyrene under the same conditions. The results demonstrated that the final sizes of bubbles as well as the average cell density of the foam were reduced by using of nucleating agent. The growth rate of bubbles was also decreased by increasing the nano Al₂O₃ particles content. In addition, influence of temperature on foam density of nanocomposite specimens was greater than unfilled polystyrene foam. In presence of nano particle, the cell density was uniformly distributed in nanocomposites specimens. The article is published in the original.     

Generation of 40-as few-cycle pulse through chirp manipulation

We discuss theoretically how supercontinuum spectra produced from high-order harmonic generation processes in a synthesized same-color laser field is optimized by adjusting the chirp parameter of the controlling pulse. Furthermore, a 40-attosecond isolated pulse with an effective bandwidth of 121 orders is obtained from He+ ion when the chirp rate ratio of pulses has a small value. The numerical results show that the efficiency of single as pulse generation is enhanced, and the quantum paths are controlled successfully. Our simulation shows that the produced pulses with high signal-to-noise ratio are obtained straightforwardly without any phase compensation. These results are explained using the classical approach.     

Optical sensing of nanoparticles in the infrared by use of silica nanowires

We numerically investigate an optical sensor in the infrared based on a Mach?CZehnder interferometer (MZI) assembled with two single-mode silica nanowires immersed in acetonitrile. We propose to use acetonitrile as the detecting solution because, in contrast to water which has very high losses in the infrared, it has negligible losses at important wavelengths of 1,300 and 1550?nm. By solving for the fundamental mode of a three-layer nanowire, we calculate the propagation constant difference between the sensing and reference arms at the output of the MZI optical sensor. For nanoparticles with a size of 12?nm and an index of refraction of 1.4, the sensitivity of the optical sensor becomes a maximum for a wire diameter of 1.23???m. An optical sensor operating at a wavelength of 325?nm and using water as the detecting solution requires nanowires with a diameter of 240?nm, which is much more difficult to implement.     

Solitary wave solutions of the nonlinear generalized Pochhammer–Chree and regularized long wave equations

In this paper, we implement some fast and high accuracy numerical algorithms to obtain the solitary wave solutions of generalized Pochhammer?CChree (PC) and regularized long wave (RLW) equations. We employ the discrete Fourier transform to discretize the original partial differential equations (PDEs) in space and obtain a system of ordinary differential equations (ODEs) in Fourier space which will be solved with fourth order time-stepping methods. The proposed methods are fast and accurate due to the use of the fast Fourier transform in combination with explicit fourth-order time stepping methods. For RLW equation we investigate the propagation of a single solitary and interaction of two and three solitary waves. Moreover, three invariants of motion (mass, energy, and momentum) are evaluated to determine the conservation properties of the problem, and the numerical schemes lead to accurate results. The numerical results are compared with analytical solutions and with those of other recently published methods to confirm the accuracy and efficiency of the presented schemes.