Modeling nonlinear waves in graphene

The graphene-based resonator and its application to mass sensing based on nonlinear waves have been poorly studied numerically [1]. The project's main objective is to model and understand how graphene behave in free and forced vibrations and calculate the nonlinear resonance frequencies

Nonlinear instability of Hele-Shaw flows with smooth viscous profiles

We rigorously derive nonlinear instability of Hele-Shaw flows moving with a constant velocity in the presence of smooth viscosity profiles where the viscosity upstream is lower than the viscosity downstream. This is a single-layer problem without any material interface. The instability of the basic flow is driven by a viscosity gradient as opposed to conventional interfacial Saffman-Taylor instability where the instability is driven by a viscosity jump across the interface. Existing analytical techniques are used in this paper to establish nonlinear instability. (C) 2008 Elsevier Inc. All rights reserved.X113sciescopu

Trapped modes in a channel containing three layers of fluids and a submerged cylinder

The problem of existence of trapped waves in fluids due to a cylinder is investigated for the hydrodynamic set-up which involves a horizontal channel of infinite length and depth and of finite width containing three layers of incompressible fluids of different constant densities. The set-up also contains a cylinder which is impermeable, fully immersed in the bottom (lower-most) fluid layer of infinite depth, and extends across the channel with its generators perpendicular to the side walls of the channel. When the ratios of the densities of the adjacent fluids differ from unity by sufficiently small quantities, the underlying mathematical problem reduces to a generalized nonlinear eigenvalue problem involving a cubic polynomial-cum-operator equation. The perturbation analysis of this eigenvalue problem suggests existence of three distinct modes with different frequencies: one of the order of one persisting at the free surface, and the other two of the order of the density ratio (except for modulo one) persisting at the two internal interfaces. The correlation between these results for the three-layer case and very recent numerical results of other authors in the two-layer case has also been addressed

Trapped modes in a channel containing three layers of fluids and asubmerged cylinder

The problem of existence of trapped waves in fluids due to a cylinderis investigated for the hydrodynamic set-up which involves a horizontal channel of infinite length and depth and of finite width containing three layers of incompressible fluids of different constant densities.The set-up also contains a cylinder which is impermeable, fully immersed in the bottom (lower-most) fluid layer of infinite depth, and extends across the channel with its generators perpendicular to the side walls of the channel. When the ratios of the densities of the adjacent fluids differ from unity by sufficiently small quantities, the underlying mathematical problem reduces to a generalized nonline are igenvalue problem involving a cubic polynomial-cum-operator equation.The perturbation analysis of this eigenvalue problem suggests existence of three distinct modes with different frequencies: one of the order of one persisting at the free surface, and the other two of the order of the density ratio (except for modulo one) persisting at the two internal interfaces. The correlation between these results for the three-layer case and very recent numerical results of other authors in the two-layer case has also been addressed

Not Available

Not AvailableCurrent rise in concentration of tropospheric ozone (O-3) has deleterious effect on growth and yield of crops. Wheat is one of the most O-3 sensitive crops. Application of Chemical antioxidants may be beneficial to lessen the harmful effects of O-3 on crops. A two year study growing wheat (variety PBW550) was carried at the farms of Indian Agricultural Research Institute, New Delhi in 2010-11 and 2011-12 to evaluate the efficacy of some natural and environment friendly antioxidant chemicals in ameliorating the negative impacts of elevated ozone on growth and productivity of wheat. The treatments were (i) charcoal filtered air (CF) (ii) 1% ascorbic acid (AA), (iii) 100 ppm quercetin (Q), (iv) 10% marigold leaves extract (Tagetes patula var pusa arpita) (T) and (v) elevated O-3 control (C). Additional 25-35 ppb of O-3 over the ambient levels was maintained in all open top chambers except the CF treatment. The seasonal daily average O-3 concentration in ambient air was 38 ppb in 2010-11 and 29 ppb in 2011-12 during the crop growth period. The exogenous application of antioxidants increased the levels of endogenous leaf ascorbic acid. The activity of antioxidant enzymes (superoxide dismutase, catalase and peroxidase) was lowered by 5 to 34% in antioxidants sprayed plants as compared to elevated O3 control (C). The application of antioxidants increased the yield of wheat by 23-26% in AA, 13-15% in Q and 8-10% in T as compared to C. The micronutrient (Cu, Fe, Zn and Mn) content of wheat grains on application of exogenous ascorbic acid was higher. The application of antioxidant chemicals was effective in alleviating the negative impacts of elevated O-3 on enzyme activity and nutritional quality of wheat which increased the growth and yield of the crop.Department of Science & Technology, Ministry of Science and Technology, Govt. of Indi