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Chamola A.,Hemwati Nandan Bahuguna Garhwal University | Singh H.,Government Post Graduate College | Naithani U.C.,Hemwati Nandan Bahuguna Garhwal University
Advanced Materials Letters | Year: 2011

(1-x)BaTiO3-xPZT(65/35) ceramics were prepared by high temperature solid state reaction technique. Structural properties of the compounds were examined using an X-ray diffraction (XRD) technique to confirm the formation of phase at room temperature. Detailed studies of dielectric properties of (1-x) BaTiO3-xPZT(65/35) for all compositions were in temperature range 30-200 °C reveal that the compound have transition temperature well above at the room temperature. While pure BaTiO3 ceramics exhibited a sharp phase transformation expected for normal ferroelectrics, phase transformation behavior of the (1-x) BaTiO3-xPZT(65/35) solid solutions became more diffuse with increasing PZT(65/35) contents. The diffusivity of the dielectric peaks in the compound exhibited the values between 1 and 2 where the higher value indicates the greater disorder in the systems. This was primarily evidenced by an increased broadness in the dielectric peak, with a maximum peak width occurring at x = 0.5. The temperature dependence of ac conductivity indicated that the electrical conductivity decrease above TC on increasing the PZT(65/35) contents. This increase in the conductivity is attributed to the increase in polarizability of the materials around Tc, due to oxygen vacancies. © 2011 VBRI press.

Tiwari P.C.,Kumaun University | Joshi B.,Government Post Graduate College
Water Resources Management | Year: 2012

The nature of terrain imposes severe limitations on the scale of productive activities as well as on the efficiency of infrastructural facilities in the Indian Himalaya. As a result, biomass based subsistence agriculture constitutes the main source of rural livelihood. During the recent past, rural resource development practices have changed in response to population increase and the resultant increased demand on natural resources as well as increasing socio-economic and political marginalization. This has brought about rapid environmental changes which have reduced the groundwater recharge in the region. About 36% of springs have dried, heads of perennial streams have dried and water discharge in springs and streams has decreased considerably resulting into severe crisis of water for drinking as well as irrigation during the past 20 years. In addition to assessing the impact of recent environmental changes on water resources, this paper attempts to develop a community and user oriented framework for the sustainable development of water resources with a case illustration of Kosi headwater in Kumaon Lesser Himalaya, India. © 2011 Springer Science+Business Media B.V.

Singh H.,Government Post Graduate College | Singh H.,Indian Institute of Technology Roorkee | Yadav K.L.,Indian Institute of Technology Roorkee
Journal of the American Ceramic Society | Year: 2014

Spinel-perovskite magnetoelectric (ME) nanocomposites xMgFe2O4-(1-x)BiFeO3, x = 0.1, 0.2, 0.3, and 0.4 were synthesized by sol-gel method and characterized by differential thermal analysis, X-ray diffraction analysis, dielectric and magnetic measurements. The samples were calcined at various temperatures and then the effect of annealing temperature on structural and magnetic properties was studied. From transmission electron microscopy, the average crystal size was found to be 30-50 nm. The magnetic behavior is found to be dependent on annealing temperature and magnesium ferrite content. The dielectric behavior with frequency and temperature has been modified with the induction of magnesium ferrite. The relative change of dielectric constant with magnetic field was observed in the nanocomposites. This relative change of magnetic field-induced dielectric constant can also be expressed by Δε∼ γM2 (where γ is magnetoelectric coupling coefficient). © 2014 The American Ceramic Society.

Verma K.L.,Government Post Graduate College
Latin American Journal of Solids and Structures | Year: 2014

Analysis for general closed form solution of the thermoelastic waves in anisotropic heat conducting materials is obtained by using the solution technique for the biquadratic equation in the framework of the generalized theory of thermoelasticity. Obtained results are general in nature and can be applied to the materials of higher symmetry classes such as transvesely isotropic, cubic, and isotropic materials. Uncoupled and coupled thermoelasticity are the particular cases of the obtained results. Numerical computations are carried out on a fiber reinforced heat conducting composite plate modeled as a transversely isotropic media. The two dimensional slowness curves corresponding to different thermal relaxations are presented graphically and characteristics displayed are analyzed with thermal relaxations. © 2014, Brazilian Association of Computational Mechanics. All rights reserved.

Tiwari P.C.,Kumaun University | Joshi B.,Government Post Graduate College
Landslide Science and Practice: Global Environmental Change | Year: 2013

In Himalaya, increasing rainfall variability has accelerated landslide activity damaging cultivated land and devastating agricultural infrastructure. Paper aims to analyze rainfall variability and interpret its linkages with landslides and food security with an example of Kumaon Himalaya. Food security in the region depends on local agricultural production, food purchasing power, and road connectivity. Study revealed that both number of rainy days as well as amount of rainfall reduced respectively by 18 % and 25 % during last 10 years, but incidences of high intensity rainfall, cloud bursts and flash floods have increased. This has triggered landside activity devastating 4.83 ha cultivated land, 800 m canals length and 3,891 m road network ever year. Consequently, food production has declined by 15 % rendering 45 % families highly vulnerable to food insecurity. Adaptive agricultural land use planning and diversification and improvement of rural livelihood could reduce vulnerability of mountain communities to climate change and food insecurity. © Springer-Verlag Berlin Heidelberg 2013.

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