Viscoelastic response of sonic band-gap materials

A brief report is presented on the effect of viscoelastic losses in a high density contrast sonic band-gap material of close-packed rubber spheres in air. The scattering properties of such a material are computed with an on-shell multiple scattering method, properties which are compared with the lossless case. The existence of an appreciable omnidirectional gap in the transmission spectrum, when losses are present, is also reported.Comment: 5 pages, 4 figures, submitted to PR

Theoretical analysis of acoustic stop bands in two-dimensional periodic scattering arrays

This paper presents a theoretical analysis of the recently reported observation of acoustic stop bands in two-dimensional scattering arrays (Robertson and Rudy, J. Acoust. Soc. Am. {\bf 104}, 694, 1998). A self-consistent wave scattering theory, incorporating all orders of multiple scattering, is used to obtain the wave transmission. The band structures for the regular arrays of cylinders are computed using the plane wave expansion method. The theoretical results compare favorably with the experimental data.Comment: 18 pages, 4 page

Residual effect of nitrogen levels and weed control methods on growth, yield and economics of wheat grown after rice

A field experiment was laid out in split plot design on residual effect of treatments comprising three nitrogen levels viz. N75 (N1), N100 (N2) and N125 (N3) in main-plot treatments and seven weed control treatments viz. (W1-butachlor + 1 Hand Weeding, W2-butachlor + 2 Mechanical Weeding, W3-butachlor + 2,4-D, W4-bispyribac sodium, W5-butachlor + bispyribac sodium, W6-HW-2, W7- control) as sub-plot treatments conducted during 2015-16 and 2016-17 at the Rajaula Agriculture Farm, MGCGVV, Satna (M.P.) to study the residual effect of N-levels and weed control methods on growth, yield and economics of wheat grown after rice. In case of succeeding wheat, the residual 125 kg N/ha performed the best with respect to growth, yield-attributes with the result 31.11 q/ha grain yield and Rs.33509/ha income. While, under sub plot treatments, Hand weedings two times were recorded significant grain yield (28.66 q/ha) and straw yield (38.17 q/ha) at (P <0.05) over control. However it was found non-significant different and also noticed higher over rest treatments. In this succession, Butachlor + 2, 4-D (0.80 kg/ha) was higher but in second position and similar trend was observed in successive way with rest of treatments

Scattering of elastic waves by periodic arrays of spherical bodies

We develop a formalism for the calculation of the frequency band structure of a phononic crystal consisting of non-overlapping elastic spheres, characterized by Lam\'e coefficients which may be complex and frequency dependent, arranged periodically in a host medium with different mass density and Lam\'e coefficients. We view the crystal as a sequence of planes of spheres, parallel to and having the two dimensional periodicity of a given crystallographic plane, and obtain the complex band structure of the infinite crystal associated with this plane. The method allows one to calculate, also, the transmission, reflection, and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness. We demonstrate the efficiency of the method by applying it to a specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press

First order antiferro-ferromagnetic transition in Fe49(Rh0.93Pd0.07)51 under simultaneous application of magnetic field and external pressure

The magnetic field-pressure-temperature (H-P-T) phase diagram for first order antiferromagnetic (AFM) to ferromagnetic (FM) transition in Fe49(Rh0.93Pd0.07)51 has been constructed using resistivity measurements under simultaneous application of magnetic field (up to 8 Tesla) and pressure (up to 20 kbar). Temperature dependence of resistivity ({\rho}-T) shows that with increasing pressure, the width of the transition and the extent of hysteresis decreases whereas with the application of magnetic field it increases. Consistent with existing literature the first order transition temperature (TN) increases with the application of external pressure (~ 7.3 K/ kbar) and decreases with magnetic field (~ - 12.8 K/Tesla). Exploiting these opposing trends, resistivity under simultaneous application of magnetic field and pressure is used to distinguish the relative effect of temperature, magnetic field and pressure on disorder broadened first order transition. For this a set of H and P values are chosen for which TN (H1, P1) = TN (H2, P2). Measurements for such combinations of H and P show that the temperature dependence of resistivity is similar i.e. the broadening (in temperature) of transition as well as extent of hysteresis remains independent of H and P. The transition width decreases exponentially with increasing temperature. Isothermal magnetoresistance measurement under various constant pressure show that even though the critical field required for AFM-FM transition depends on applied pressure, the hysteresis as well as transition width (in magnetic field) both remains independent of pressure, consistent with our conclusions drawn from {\rho}-T measurements.Comment: 10 pages, 6 figure