Aspects of Dielectric Breakdown in a Model for Disordered Nonlinear Composites

We study dielectric breakdown in a semi-classical bond percolation model for nonlinear composite materials introduced by us and the related breakdown exponent near the percolation threshold in two dimensions. The breakdown exponent after doing finite size scaling analysis is found to be $t_B \simeq$ 1.42. We discuss in detail the differences in our model from the traditional models for dielectric breakdown and argue that our result seems to be different from the standard result of 4/3 obtained in the previous models.Comment: 20 pages, LaTex file (6 postscript figures included

Macronutrient status and yield stability of arecanut (Kahikuchi) under integrated nutrient management practice in Assam

A long term field   experiment was carried out in clay-loam soil at ICAR-CPCRI, Kahikuchi campus,   Guwahati, Assam during 2000-2012 with arecanut variety Kahikuchi with seven   nutrient combinations. The treatments included control (T1), 100 per cent   vermicompost (T2), 200 per cent vermicompost (T3), 100 per cent chemical   fertilizer (T4), 50 per cent vermicompost + 50 per cent chemical fertilizer   (T5), 1/3rd vermicompost + 2/3rd chemical fertilizer   (T6) and 2/3rd vermicompost + 1/3rd chemical fertilizer   (T7). The treatment T7 produced highest fresh ripened arecanut yield of 16.7   kg i.e., about 3.6 kg dry chali per palm. Positive correlations were   obtained between yield of arecanut and soil available N, P, K content.   Significant and positive correlation was found between leaf N, P, K and   available N, P, K content in surface and sub-surface soil. Available N, P and   K content increased over the year under nutrient applied plot that reflected   in yield of arecanut. The average yield in various treatments followed in the   order of T7 > T5 = T6 > T2 = T3 > T4 > T1. The application of   targeted, sufficient and balanced quantities of organic and inorganic   fertilizer will be the need of the hour to make nutrients available for   higher yield, soil fertility maintenance and agricultural sustainability   without polluting environment

Chemical extraction and optimization of intracellular β-galactosidase production from the bacterium Arthrobacter oxydans using Box-Behnken design of response surface methodology

Present study demonstrated the isolation of most promising β-galactosidase producing bacterial strain SB from soil. Morphological, biochemical, and 16s rRNA sequence analysis identified the bacterial strain as Arthrobacter oxydans. Several chemicals, including SDS, Triton X-100, Tween 20, isoamyl alcohol, and toluene-acetone mixture, were applied for extraction of intracellular β-galactosidase from the bacterial strain Arthrobacter oxydans. Among these, Tween 20 was recorded to be most effective. Role of pH, temperature, and shaker speed on production of β-galactosidase was evaluated using Box-Behnken design of response surface methodology. According to Box-Behnken analysis, optimum production of β-galactosidase (21.38 U (mg–1 protein)) is predicted at pH 6.76, temperature 36.1 °C, and shaker speed 121.37 r.p.m. The parameters are validated with the nearest value

An Analytical Study on the Multi-critical Behaviour and Related Bifurcation Phenomena for Relativistic Black Hole Accretion

We apply the theory of algebraic polynomials to analytically study the transonic properties of general relativistic hydrodynamic axisymmetric accretion onto non-rotating astrophysical black holes. For such accretion phenomena, the conserved specific energy of the flow, which turns out to be one of the two first integrals of motion in the system studied, can be expressed as a 8$^{th}$ degree polynomial of the critical point of the flow configuration. We then construct the corresponding Sturm's chain algorithm to calculate the number of real roots lying within the astrophysically relevant domain of $\mathbb{R}$. This allows, for the first time in literature, to {\it analytically} find out the maximum number of physically acceptable solution an accretion flow with certain geometric configuration, space-time metric, and equation of state can have, and thus to investigate its multi-critical properties {\it completely analytically}, for accretion flow in which the location of the critical points can not be computed without taking recourse to the numerical scheme. This work can further be generalized to analytically calculate the maximal number of equilibrium points certain autonomous dynamical system can have in general. We also demonstrate how the transition from a mono-critical to multi-critical (or vice versa) flow configuration can be realized through the saddle-centre bifurcation phenomena using certain techniques of the catastrophe theory.Comment: 19 pages, 2 eps figures, to appear in "General Relativity and Gravitation

Reserve Estimation of Proposed Opencast Mine of Ramnagore Colliery

As jhama and burnt coal are saleable items with sizeable demand in different small and medium scale industries, the management of Ramnagore Colliery of Steel Authority of India Ltd. (SAIL) has decided to mine jhama, burnt coal, coal and the strata of jhama intruded by mica peridotite from Salanpur D-2, Salanpur D-1 and Salanpur C seams in a block near north-eastern boundary of the colliery, covering a total area of around 22.01 hectare. The proposed mine is located in Ramnagore part of Indikatta-Ramnagore Block on the eastern bank of the Barakar River in Raniganj Coalfield. This paper describes the methodology of reserve estimation along with estimation of pit life, waste and stripping ratio. Geological report by Central Mine Planning & Design Institute Ltd. (CMPDI) in 1995 forms the basis of the geological information of the area. The report indicates that due to pyrolysis, the seams have been transformed into a combination of layers of jhama, burnt coal, coal and the layers of jhama intruded by mica peridotite. Of the 15 boreholes in and around the proposed opencast mining site, lithologs of only 13 boreholes are available with the mine management and only 8 boreholes fall inside the proposed mining area. The classification of seams in the lithology of the boreholes is neither very clear, nor very convincing. The results indicate that it would be much more economic to mine the site en bloc than to mine Western and Eastern blocks separately leaving a 90 m wide barrier in between them to protect the existing high voltage electric supply line. In isolation, the West Block, which covers nearly two-third of the whole site, will run for two-and-half years, producing a little more than 40% of the total mineable reserve of the whole site and generating 63% of the total waste likely to be generated had the whole site been mined as one. Overall stripping ratio of the Western Block will be 8.36 M3/t, i.e. nearly one and half times of the stripping ratio of 5.47 M3/t, expected for the mining of the whole site in one go. The Eastern block that covers only about 15% of the whole site will result in production for only two months. The production will comprise not even 3% of the total mineable reserve in the whole site, that too with a high oveall stripping ratio of 12.82 M3/t. On the other hand, if the whole site is mined en bloc, the mine is likely to run for six years yielding more than 0.7 million tonne of minerals (coal, burnt coal and jhama together) with a stripping ratio of 5.47 M3/t approximately

Disaster due to coal Mines Explosions

This paper deals with an account of occurrences and causes behind disaster due to explosions in Indian mines. Principal causes and mechanism s of explosion, and precautions against explosion are also discussed. The review indicated that although frequency of occurrence of explosion inducted disasters have reduced over the years in coal mines of India, there is a need of implementation of modern technologies such as environmental tele-monitoring system in fire prone mines in general, and in degree II/III gassy mines in particular, to arrive at the zero-disaster regime. There is a need for an additional categorization of gassiness of seam such as degree IV gassy seam for the seam where rate of gas emission is more than m3 per tonne of coal raised. Arrangement for methane drainage or coal seam degasification or cal bed methane recovery should be given top priority on degree III and proposed degree IV mine

Period dependent temperature and ambient index effects on long period fibre gratings

The ambient index and temperature effects on the spectral profiles of two sets of long period gratings (LPGs) of different periods were investigated. The shorter period LPGs were found to be more sensitive than the longer period LPGs over identical ambient index ranges but less sensitive over identical temperature ranges. The coupling wavelength shifts due to temperature are also seen to be linear and in opposite directions in each set of LPGs and unlike the ambient index shifts there seems to be no obvious modal dependency with respect to sensitivity in any individual LPG. The conclusion to this investigation is that it may be possible to design an LPG of such a period that parts of the spectral profile are unaffected by temperature whilst maintaining a reasonable ambient index sensitivity

Coal mine fires - hazards and modern control techniques

Fires have long been recognized as hazards associated with coal mining. Coal mine fire causes economic losses by virtue of loss of coal and coal winning machinery. Environmental problems at surface and underground due to coal mine fire are discussed in terms of production of noxious, toxic gases, global warming and fire damp explosion. Social and health problems due to mine fire are dealt with. An account of modern techniques like water mist technology, remote sensing and infusion of carbon dioxide are also given