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This paper is deals with the non-axisymmetric dynamic response of imperfectly bonded buried orthotropic empty thin pipelines subjected to incident compressional wave (P-wave). In the thin shell theory the effect of shear deformation and rotary inertia is not considered. The pipeline has been modeled as an infinite cylindrical shell imperfectly bonded to surrounding. An approach similar to Dwivedi and Upadhyay (1989) has been followed wherein a thin layer is assumed between the shell and the surrounding medium (soil) such that this layer possesses the properties of stiffness and damping both. The degree of imperfection of the bond is varied by changing the stiffness and the damping parameters of this layer. Numerical results have been presented for the case of an incident plane longitudinal compressional wave (P-wave) only. The flexural mode (Non-axisymmetric) response has been discuss, it has been found that assumption of a perfect bond may not always lead to a safe and conservative estimate of the shell displacements and, hence consideration of the bond imperfection in non-axisymmetric mode response is necessary. © EuroJournals Publishing, Inc. 2010. Source

Verma A.K.R.,Indian Institute of Technology Kharagpur | Kumar A.,It Bhu
Journal of Mines, Metals and Fuels | Year: 2011

About 75% of India's energy supply is from 120 coal based thermal power plants and produce about 160 mt of fly ash in 2009. An estimate shows that, a 200 MW power plant generates about 80 tonnes of fly ash per hour. According to Gazette of India 2008, "fly ash" means and includes all categories or groups of coal or lignite ash generated at the thermal power plant such as electrostatic precipitator (ESP) ash, dry fly ash, bottom ash, pond ash and mound ash. Dumping of fly ash occupies huge land space (about 1,00,000 acres in 2005), and it is estimated that about one acre per MW of land is needed for its disposal. Fly ash produced as a result of burning of coal has detrimental effects on environment. There are ample scope for its environmental friendly utilization in different applications in underground mines such as a raw material for backfill, support unit, construction work in underground coal mines as well as for recultivation and restoration purposes of opencast mines due to its pozzolanic characteristics. In this work, an investigation is carried out to develop a fly ash based composite of considerable compressive strength. The composites thus developed can be used to make a load bearing units in an underground mines. Source

In this study, the roots of Viburnum punctatum Buch.-Ham. ex D.Don, Viburnum coriaceum Blume, and Viburnum erubescens Wall. ex DC. were collected from the Nilgiri and Coimbatore hills in Tamil Nadu, India. Transverse sections of plant roots were prepared with the aid of a rotary microtome. The sections, each at a thickness of 10 μm, were stained and fixed in Canada balsam and the morphoanatomical features of each specimen were noted. The specimens were powdered using a mechanical grinder and were mounted in suitable media for starch grains, sclereids, druses, fibres, and vessels. Morphoanatomical features of diagnostic importance were recorded under different magnifications, followed by the determination of dimension and histological features of root components using a calibrated eyepiece micrometer and a polariser. The starch grains averaged 12, 17, and 20 μm in diameter in V. erubescens, V. punctatum, and V. coriaceum, respectively. The fibres were about 1 mm long in V. punctatum and V. coriaceum, whereas those found in V. erubescens specimens were around 700 μm. Qualitative chemical screening indicated that phytosterols, triterpenoids, and phenolic compounds and their glycosides were among the commonly found phytoconstituents. © TÜBİTAK. Source

Verma A.K.,It Bhu | Deb D.,Indian Institute of Technology Kharagpur
Geotechnical and Geological Engineering | Year: 2010

The paper discusses the concept and methodologies for the development of longwall face stability index (LFSI). LFSI is used for estimation of chock-shield pressure and face convergence. The index comprises of engineering properties of main roof, depth of mining, different support capacities and mechanical properties of coal seam being mined and provides a numerical value in the range of -6.17 to 8.13. In this study, 324 finite element models of longwall panel are developed based on various combinations of geomining conditions of Indian coal measure strata. The LFSI is an outcome of the results from finite element models. This paper illustrates a real life example for the estimation of chock shield pressure and face convergence based on LFSI. Validation of the LFSI based calculation is carried out with the field monitored data and found that the LFSI based approach is sufficient to forecast face stability parameters at longwall face. © 2010 Springer Science+Business Media B.V. Source

Singla P.,Thapar University | Mehta R.,Thapar University | Berek D.,Slovak Academy of Sciences | Upadhyay S.N.,It Bhu
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry | Year: 2012

Poly(lactic acid) (PLA) has been synthesized catalytically under vacuum by microwave (MW) irradiation using stannous octoate (SnOct 2) as catalyst. The polymerization is carried out at 180°C up to 30min. PLA with a molar mass of 10 4 g.mol -1 and a yield over 97% was produced in 20min by the ring-opening polymerization of L-lactide using (SnOct 2) as catalyst under microwave irradiation with a power level of 180W. The structural investigations are done by NMR and FTIR. The average molar mass of PLA is determined by means of size exclusion chromatography, (SEC). The characterization is done using three different columns. The polymerization rate is much faster with microwave heating than conventional heating. Microwave irradiation gives rapid energy transfer and high-energy efficiency, hence, a faster reaction rate. Copyright © Taylor and Francis Group, LLC. Source

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