Numerical modelling-based pillar strength estimation for an increased height of extraction

Underground extraction of total thickness of a thick coal seam in single lift by bord and pillar method increases pillar height during retreat. Field studies found that the increase in pillar height affects the depillaring operation adversely, especially, during caving of the strong/massive roof strata. Dilution in strength due to the increased pillar height caused catastrophic failure of barrier pillars and goaf overriding. This warrants a systematic study of pillar strength variation for the different heights of pillar. A review of different pillar strength estimation approaches for an analysis of the dilution in strength of the heightened pillar suggested that numerical modelling provides a better option for such a systematic study. Accordingly, investigations are conducted on simulated models in laboratory adopting a recognised numerical modelling procedure. The observed nature of variations in pillar strengths with the increase in its height in the numerical models and empirical formula is found to be matched. But a mismatch is found between the strength values of the two approaches with an increase in height of the pillar. Considering validity of the empirical formulation in Indian coalfields, a relationship is developed to incorporate a correction in the strength values of the numerical models. The suggested correction on the basis of this simple study of the pillar strength variation would be helpful for the use of the established simulation tool during the depillaring of a thick coal seam.     

Climate change impact in the Western Himalaya: people’s perception and adaptive strategies

The Himalaya represents a vast mountain system and globally valued for its significant role in regulation of global as well as regional climate that has direct impact on biodiversity and ecosystem services crucial for sustenance of millions of people in Himalaya and adjoining areas. However, mountain regions worldwide are impacted by climate change and at the same time represent distinctive area for the assessment of climate related impacts. Climate change impacts in Himalayan region have its implications on food production, natural ecosystems, retreat of glacier, water supply, human and animal health and overall human well being. The livelihood and food security of the people inhabited in region largely depend on climate sensitive sectors i.e. agriculture, livestock, forestry and their interlinkages with each other, and has the potential to break down food and nutritional security as well as livelihood support systems. People’s perception and understanding of climate can be an important asset when it comes to adaptation to climate change impact; however it is not taken into consideration for the development of policy design and implementation of modern mitigation and adaptation strategies by governments and other civil society organizations. The knowledge of local people and farming communities for rural landscape management and sustainable use of bioresources is gaining credence as a key strategy to cope up with the climate change. Therefore, the present study analyzes the indigenous knowledge of local people and their perceptions on climate change, and also documented adaptation approaches at local level in mountain ecosystem of western Himalaya. The study could be useful to policy makers to design appropriate adaptation strategies to cope up with the impacts of climate change.     

Finite volume approach for finite strain consolidation

The paper presents the finite volume formulation and numerical solution of finite strain one‐dimensional consolidation equation. The equation used in this study utilises a nonlinear continuum representation of consolidation with varying compressibility and hydraulic conductivity and thus inherits the material and geometric nonlinearity. Time‐marching explicit scheme has been used to achieve transient solutions. The nonlinear terms have been evaluated with the known previous time step value of the independent variable, that is, void ratio. Three‐point quadratic interpolation function of Lagrangian family has been used to evaluate the face values at discrete control volumes. It has been shown that the numerical solution is stable and convergent for the general practical cases of consolidation. Performance of the numerical scheme has been evaluated by comparing the results with an analytical solution and with the piecewise piecewise‐linear finite difference numerical model. The approach seems to work well and offers excellent potential for simulating finite strain consolidation. Further, the parametric study has been performed on soft organic clays, and the influence of various parameters on the time ate consolidation characteristics of the soil is shown. Copyright © 2015 John Wiley & Sons, Ltd.     

Motions, relative positions, and sizes of continua and bursts in solar noise storms

We present multifrequency radioheliograph observations of solar radio noise storms. The data base consists of observations carried out over 7 different days in the spring months of 1992 and 1993. In all, we present about 82 hours of data with 1 s time resolution at 4 different frequencies between 164 and 410 MHz. The spatial resolutions in the EW and NS directions vary with frequency from 1.2 to 0.8 and 3.7 to 1.5 arc min, respectively. In order to study the characteristics of bursts and continuum, we have developed a method for separating them in the time domain at each frequency. Our main results are: (i) there are no systematic large-scale motions of the continuum, the position is usually stable to within 2 of arc over durations of 3–4 hours and more; (ii) the positions of the continuum at different frequencies are often closer to each other than 1 of arc and have strongly correlated small-scale motions; (iii) the bursts have their positions scattered over the continuum extent and are slightly smaller in size than the underlying continuum; and (iv) there is no evidence for bipolar structures. We discuss the implications of these results for the current models of noise storm emission and for the trapping of suprathermal electrons.Presented at the CESRA Workshop in Potsdam, Germany, 16–20 May, 1994.     

Nonlinear Viscous Damping of Surface AlfvÉn Waves in Polar Coronal Holes

We quantitatively re-examine the nonlinear viscous damping of surface Alfvén waves in polar coronal holes, using recently reported observational data on electron density and temperature and the magnetic field spreading near the edges. It is found that in the nonlinear regime the viscous damping of surface Alfvén waves becomes a viable mechanism of solar coronal plasma heating when strong spreading of magnetic field is taken into account. Our estimations confirm that coronal heating is more pronounced in the nonlinear case than in the linear one in presence of magnetic field spreading.     

Kinematics of horizontal simple shear zones of concentric arcs (Taylor–Couette flow) with incompressible Newtonian rheology

We present preliminary kinematic analyses of Taylor–Couette flow. We consider deformation of a Newtonian incompressible ductile material inside rotating horizontal listric (concentric circular) boundaries. The velocity profile is curved indicating non-uniform shear strain but leads to the same shear sense. Each material point on progressive shear keeps increasing shear strain linearly with time. A curve of no movement, the ‘neutral curve’, may exist inside the shear zone. Irregular geometries of initially regular markers and their individual non-matching strain paths indicate inhomogeneous deformaion in such Taylor–Couette flow.     

Chemical composition and palaeobotanical origin of Miocene resins from Kerala-Konkan Coast,western India

The terpenoid composition of resins from the Miocene lignite horizons from the Kerala-Konkan Coast, western India was analyzed by Curie-point pyrolysis-gas chromatography-mass spectrometry (Cupy-GC-MS). The major pyrolysates were cadalene-based bicyclic sesquiterpenoids including some C₃₀-C₃₁ bicadinenes and bicadinanes typical of dammar resin from angiosperm plants of Dipterocarpaceae family. These plants are typically supported by tropical climates which the western Indian region was known to have experienced during early Tertiary period. The present study suggests that these palaeoclimatic conditions persisted until at least the Miocene epoch. These sesquiterpenoids which are commonly detected in many SE Asian crude oils may be utilised as useful biomarkers for petroleum exploration in the western Indian region.     

Palaeoproterozoic metamorphism in the Jeori-Wangtu Gneissic Complex (JWGC), western Himalayas

The Jeori-Wangtu Gneissic Complex (JWGC) exposed as a tectonic window in the Lesser Himalayas represents one of the oldest Gneissic Complex of the Himalayas. Foliated granite and the metapelite constitute the dominant lithologies of the JWGC. The western margin of the JWGC is bounded by a brittle shear while in the east, the tectonic surface is a ductile shear zone.Kyanite schist, chloritoid schist, staurolite schist (St-1), garnet schist and staurolite schist (St-2) are present in a west to east sequence beginning from near to the Jhakhri thrust and up to the contact with the JWGC granite. Mica schist is intermittently present and is the dominant metapelite. Low to medium grade regional metamorphic conditions has been inferred for these rocks.Calc silicate enclaves within the JWGC granite preserve the contact metamorphic effects. These are reflected in development of narrow zones of disequilibrium assemblages of calcareous garnet (grs₅₃), clinopyroxene, K feldspar, calcic plagioclase (An₈₆), quartz, zoned sphene, zoned allanite, amphiboles, calcite and epidote.Recording of contact metamorphic assemblage of 1.80 Ga granite witin the enclave calc silicates and in the host metapelites over an earlier, relict low to medium grade assemblage indicates that the JWGC preserves palaeoproterozoic metamorphic imprints.     

Mitigating people-park conflicts on resource use through ecotourism: A case of the Nanda Devi Biosphere Reserve, Indian Himalaya

Ecotourism aims to deliver the philosophy of sustainable development through environmental conservation as well as socio-economic development. Areas with rich biodiversity and scenic beauty, like the Indian Himalayan region, have been one of the major destination centers for nature lovers from historical time. In view of conserving the rich biodiversity and natural heritage of the Himalayan region 92 protected areas have been set aside, of these Nanda Devi Biosphere Reserve (NDBR) is a well known world heritage site. Over a period of time establishing NDBR has invited conflicts between the local people and reserve authorities on the management approaches and utilization criteria of the natural resources, especially banning the traditional bio-resource collection rights of local community, expeditions, trekking, and other anthropogenic activities in the core zones. The present study aims to understand and analyze the various people - park conflicts, and also to suggest ways to mitigate such conflicts in view of biodiversity conservation and improvement of economic status of local people by promoting ecotourism. With this view the study further discusses the various aspects of ecotourism, its pros and cons, and the avenues of developing appropriate strategies for promotion of ecotourism in buffer zone areas of NDBR.     

Application of In-situ Lysimetric Studies for Determining Soil Hydraulic Conductivity

Several techniques such as laboratory column studies, under normal and accelerated gravity environments, numerical modeling and pedo-transfer functions have been employed by previous researchers to determine hydraulic conductivity of soils. However, these methods suffer with several limitations, particularly, as far as regeneration of in-situ soil conditions and boundary conditions, in an exceptionally small model, are concerned. Under these circumstances, in-situ lysimeters are found to be quite useful for conducting the investigations to obtain hydraulic conductivity of fully saturated or partially saturated soils. These lysimeters can easily be installed in the soil mass, without disturbing its state, and are large enough to exhibit representative soil mass that exist at the site. With this in view, an attempt was made in this study to determine hydraulic conductivity of the soil mass beneath a waste disposal site in India by installing a lysimeter. Details of the instrumentation are presented in this paper along with the methodology to determine hydraulic conductivity of the soil mass.