Free Vibration Analysis of an Eccentric Thermoelastic Hollow Cylinder

The three-dimensional free vibrations in a simply supported homogeneous isotropic, thermally conducting, circular cylinder of finite length with an eccentrically located inner circular cavity have been studied. The surfaces of the cylinder are subjected to stress free and thermally insulated or isothermal boundary conditions. The three-dimensional linear theory of coupled thermoelasticity has been employed to model the problem. The displacement potential functions have been introduced to decouple purely shear and longitudinal motions. The purely transverse wave has been found to remain unaffected due to thermal field. The translation addition theorem for cylindrical wave functions along with orthogonal series expansions has been used to develop the exact solution. To illustrate the analytical results, the numerical solution of some relations and equations have been obtained to compute lowest frequency and dissipation factor versus eccentricities, for selected length to radius ratio and radius ratio of hollow cylinder. The computer simulated results have been carried out with the help of MATLAB software and are presented graphically.     

Chemopreventive Effect of Different Ratios of Fish Oil and Corn Oil in Experimental Colon Carcinogenesis

n-3 Polyunsaturated fatty acids (PUFA) have a chemopreventive effect while n-6 PUFA promote carcinogenesis. The effect of these essential fatty acids may be related to oxidative stress. Therefore, the study was designed to evaluate the effect of different ratios of fish oil (FO) and corn oil (CO) in the prevention of colon cancer. Male Wistar rats were divided into control, dimethylhydrazine dihydrochloride (DMH) treated, FO + CO (1:1) and FO + CO (2.5:1). All the groups, except the control received a weekly injection of DMH for 4 weeks. The animals were sacrificed either 48 h later (initiation phase) or kept for 16 weeks (post initiation phase). DMH treatment in the initiation phase animals showed mild to moderate inflammation, decreased ROS and TrxR activity, increased antioxidants, apoptosis and ACF multiplicity. The post initiation study showed severe inflammation with hyperplasia, increased ACF multiplicity and ROS levels, a decrease in antioxidants and apoptosis. The FO + CO (1:1) treated animals showed severe inflammation, a decrease in ROS, an increase in antioxidants and apoptosis in the initiation phase. FO + CO (1:1) in the post initiation phase and FO + CO (2.5:1) in the initiation showed mild inflammation, increased ROS, apoptosis and decreased antioxidants. There was a decrease in ACF multiplicity and ROS levels, increased antioxidants and apoptosis in the post initiation phase study. The present study suggests that FO has a dose- and time-dependent chemopreventive effect in colon cancer mediated through oxidative stress and apoptosis.     

Natural convection MHD mass transfer through an infinite vertical porous plate in the existence of radiation embedded in porous medium

This research focuses on studying the effects of heat and mass transfer convective flow passing through an infinite vertical plate embedded in porous media under radiation and chemical reaction with constant heat and mass flux. A magnetic field of strength is functional throughout the fluid region. The novelty of the present work is to examine the heat and mass transfer magnetohydrodynamics flow in the presence of thermal radiation. The equations governing the flow, heat and mass transfer are solved analytically using the perturbation technique. Expressions for velocity, temperature, concentration, skin-friction, Nusselt, and Sherwood numbers are obtained. The influence of physical parameters on the flow domain is described graphically and in tabular form. It is found that increase in radiation parameter reduces the velocity and temperature. Moreover, internal friction of the plate decreased with increasing values of radiation parameter.     

Modelling of hybrid energy system—Part II: Combined dispatch strategies and solution algorithm

Computer simulation is an increasingly popular tool for determining the most suitable hybrid energy system type, design and control for an isolated community or a cluster of villages. This paper presents the development of the optimum control algorithm based on combined dispatch strategies, to achieve the optimal cost of battery incorporated hybrid energy system for electricity generation, during a period of time by solving the mathematical model, which was developed in Part I of this tri-series paper.The main purpose of the control system proposed here is to reduce, as much as possible, the participation of the diesel generator in the electricity generation process, taking the maximum advantage of the renewable energy resources available.The overall load dispatch scenario is controlled by the availability of renewable power, total system load demand, diesel generator operational constraints and the proper management of the battery bank. The incorporation of a battery bank makes the control operation more practical and relatively easier.     

Effect of air ambient on surface recombination and determination of diffusion length in silicon wafer using photocurrent generation method

An n⁺-p-p⁺ structure was formed by depositing a thin Al layer on one side and a semitransparent Pd layer on other side of a p-Si wafer, and the diffusion length L was determined from the slope of short circuit current density J_sc vs. illumination intensity P_in characteristics by illuminating the p⁺ side with a laser light of wavelength λ = 789 nm, following the photocurrent generation method. The slope was found to decrease after the specimen was exposed to air for a few hours before the measurement. The present investigation revealed that the degradation of slope was owing to increase in surface recombination velocity S significantly, e.g. to 2800 cm/s for air exposure of 8 h, above its initial value 10 cm/s. This resulted from adsorption of moisture on Pd surface which decreases work function of Pd and lowers the accumulation potential barrier. The adsorbed water molecules could be removed from Pd surface by vacuum pumping and then S again became small and the slope regained its original value. The true value of L, smaller or larger than the wafer thickness, can be determined using single monochromatic illumination if S is known or has a negligibly small value, as in our case where the specimen was stored in vacuum. In our specimen we determined L = 56 μm when S was negligibly small. However, using the experimental slopes of J_sc-P_in curves at two monochromatic illuminations obtained by Sharma et al. we determined both S and L and found their values 1390 cm/s and 94 μm, respectively.     

Vietnam's energy sector: A review of current energy policies and strategies

Since the introduction of market-oriented economy in 1986, Vietnam has made noticeable socio-economic progress. In this progress, the energy sector has played a vital role. This role is likely to deepen in the years to come as Vietnam strives to achieve even higher levels in economic progress. Such deepening in the role of energy, this paper argues, will heighten concerns about the security of energy supply, and economic, environmental, social and political consequences. In order to address these issues, Vietnam has over the last decade, developed a suite of energy policies. A deeper review of these policies suggests that they are typified by economic-growth orientation, exclusive focus on a single-sector or single issue, and largely neglect the significance of cross-sectoral and cross-thematic issues arising from the interdependencies between energy, economy, and the polity at large. The existing energy policy settings are, therefore, unlikely to be able to provide a satisfactory redress to the challenges noted above. This paper provides an overview of the current energy policies with a view to identify areas where further policy effort is needed in order to facilitate a sustainable development of the Vietnamese energy sector.     

A numerical study on nonlinear DPL model for analyzing heat transfer in tissue during thermal therapy

In the present paper, therapeutic treatment of infected tumorous cells has been studied through mathematical modeling and simulation of heat transfer in tissues by using a nonlinear dual-phase lag bioheat transfer model with Dirichlet boundary condition. The components of volumetric heat source in this model such as blood perfusion and metabolism are assumed experimentally validated temperature-dependent function, which gives more accurate temperature distribution in tissues through this model. We have used the finite difference and RK (4, 5) techniques of numerical methods to solve the proposed problem and obtained the exact solution in a particular case. After comparison, we got a good agreement between them. We have used dimensionless quantities throughout this paper. The effect of relaxation and thermalization time with respect to dimensionless temperature distribution has been analyzed in the treatment process.     

Analytical approach on magnetohydrodynamic Casson fluid flow past a stretching sheet via Adomian decomposition method

Flow phenomena of three-dimensional conducting Casson fluid through a stretching sheet are proposed in the present investigation with the impact of the magnetic parameter in a permeable medium. The adaptation of particular transformations is useful to modify the governing equations into their nondimensional as well as the ordinary form. However, these transformed equations are nonlinear and approximate analytical methods for the solution of the complex form of governing equations. In particular, the Adomian decomposition method is proposed for the solution. The behavior of several variables, such as the magnetic and porous matrix, on the flow profile as well as the rate of shear stress, are discussed via graphs and tables. The conformity of the current result with the earlier study shows a road map for further investigation. The major concluding remarks are; the retardation in the velocity distribution is rendered due to an increase in the Casson parameter moreover, the Casson parameter favors in reducing the rate of shear stress coefficient in magnitude.     

Hybrid NOMA for Future Radio Access: Design,Potentials and Limitations

Wireless Personal Communications - Next-generation internet of things (IoT) applications need numerous low-powered wireless mobile devices to connect with each other, having ultra-reliability and...