Dynamic stress concentration in pre-stressed poroelastic media due to moving punch influenced by shear wave     

Abhishek Kumar Singh  Anil Negi  Ram Prasad Yadav  Amit Kumar Verma 《Journal of Seismology》2018,22(5):1263-1274

During the occurrence of earthquake, the shear wave propagates in the rocks present inside/at the Earth’s crust. The propagation of shear wave may lead to the progression of punch present inside the rock medium. As a result of this, substantial stress accumulated at the vicinity of propagating punch inside rock medium which significantly affects the stability of various geological and human-made structure and, hence, may cause failure of structure. Therefore, the analysis of stress concentration at the vicinity of punch moving due to shear wave propagation has become prominent in the area of seismology. In the present paper, an analytical perspective has been employed to discuss the influence of velocity of moving punch associated with the propagation of shear wave on developed dynamic stress concentration (DSC) in three types of pre-stressed vertical transversely isotropic (VTI) poroelastic media viz. granite (an igneous rock); sandstone (a sedimentary rock); and marble (a metamorphic rock). The closed form expression of DSC for the force of constant intensity has been derived with the aid of Weiner-Hopf technique along with Galilean and two-sided Fourier integral transformations. The noticeable influence of different affecting parameters (viz. velocity of moving punch associated with the shear wave propagation, horizontal compressive/tensile initial stresses, vertical compressive/tensile initial stress, porosity, and anisotropy parameter) on dynamic stress concentration has also been reported. Numerical computation and graphical illustrations have been carried out for the aforementioned three different types of porous rocks to investigate the profound impact of affecting parameters on DSC. Moreover, some noteworthy peculiarities have also been derived from the obtained expression of dynamic stress concentration.  相似文献   

Dramatic decline of Arctic sea ice linked to global warming     

Yadav  Juhi  Kumar  Avinash  Mohan  Rahul 《Natural Hazards》2020,103(2):2617-2621

Natural Hazards - Arctic sea ice has declined rapidly over the past four decades at the rate of ??4.7% per decade leading to an imbalance in the oceanic heat flux. The study reported...  相似文献   

Static spherically-symmetric perfect fluids with pressure equal to energy density     

R. B. S. Yadav  S. L. Saini 《Astrophysics and Space Science》1991,186(2):331-336

The present Letter represents an exact, static, and spherically-symmetric solution of Einstein's field equations for a homogeneous perfect fluid core surrounded by a field of Zeldovich's fluid which is asymptotically homaloidal.  相似文献   

Monitoring spatio-temporal pattern of drought stress using integrated drought index over Bundelkhand region,India   总被引：1，自引：1，他引：0  

N. R. Patel  Kamana Yadav 《Natural Hazards》2015,77(2):663-677

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Multifractality in seismic sequences of NW Himalaya     

Chamoli  Ashutosh  Yadav  R. B. S. 《Natural Hazards》2013,77(1):19-32

Multifractal behaviour of interevent time sequences is investigated for the earthquake events in the NW Himalaya, which is one of the most seismically active zones of India and experienced moderate to large damaging earthquakes in the past. In the present study, the multifractal detrended fluctuation analysis (MF-DFA) is used to understand the multifractal behaviour of the earthquake data. For this purpose, a complete and homogeneous earthquake catalogue of the period 1965–2013 with a magnitude of completeness M _w 4.3 is used. The analysis revealed the presence of multifractal behaviour and sharp changes near the occurrence of three earthquakes of magnitude (M _w ) greater than 6.6 including the October 2005, Muzaffarabad–Kashmir earthquake. The multifractal spectrum and related parameters are explored to understand the time dynamics and clustering of the events.

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Potential environmental pollution hazards by coal based power plant at Jhansi (UP) India     

Ganesh Chandra Kisku  Sandeep Yadav  Rajnish Kumar Sharma  Mahendra Pal Singh Negi 《Environmental Earth Sciences》2012,67(7):2109-2120

Coal, a fossil fuel, is the largest source of energy for the generation of electricity in India. In order to study the potential environmental hazards by coal based power plants, particulate matters were collected using Stack Monitoring Kit and gaseous pollutants by Automatic Flue Gas Analyzer. The morphological and chemical properties, mineralogical composition and particle size distributions have been determined by SEM–EDX, XRD and CILAS. The data revealed the presence of particulate matters, SO₂, NOx in the range of 236–315, 162–238, 173–222 mg/Nm³ respectively. The emission of CO₂ was in the range of 43,004–60,115 Nm³/h with an average of 52,830 Nm³/h. Among the elements, Fe > Mn > Al > Zn > B > Ni > Cr > Cu were present in substantially higher proportion than Pb > Mo > Cd > Se > As > Hg. It was found that most of the elements were concentrated on fly ash surface rather than coal, bottom ash and pond ash. This variation may be attributed to the fineness of fly ash particles with large surface ratio to mass. Mineralogical studies of coal and fly ash by X-ray diffraction revealed the presence of mullite, quartz, cristobalite and maghemite. Presence of mullite and quartz found in fly ash indicate the conversion of complex minerals to mullite and quartz at high temperature. Transfer Coefficient was calculated to determine the ratio of the enrichment of trace elements in fly or bottom ash with respect to coal and pond ash.  相似文献   

Instruments of RT-2 experiment onboard CORONAS-PHOTON and their test and evaluation III: Coded Aperture Mask and Fresnel Zone Plates in RT-2/CZT payload     

Anuj Nandi  S. Palit  D. Debnath  Sandip K. Chakrabarti  T. B. Kotoch  R. Sarkar  Vipin K. Yadav  V. Girish  A. R. Rao  D. Bhattacharya 《Experimental Astronomy》2011,29(1-2):55-84

Imaging in hard X-rays of any astrophysical source with high angular resolution is a challenging job. Shadow-casting technique is one of the most viable options for imaging in hard X-rays. We have used two different types of shadow-casters, namely, Coded Aperture Mask (CAM) and Fresnel Zone Plate (FZP) pair and two types of pixellated solid-state detectors, namely, CZT and CMOS in RT-2/CZT payload, the hard X-ray imaging instrument onboard the CORONAS-PHOTON satellite. In this paper, we present the results of simulations with different combinations of coders (CAM & FZP) and detectors that are employed in the RT-2/CZT payload. We discuss the possibility of detecting transient Solar flares with good angular resolution for various combinations. Simulated results are compared with laboratory experiments to verify the consistency of the designed configuration.  相似文献   

Synthesis of geological and airborne geophysical data for prognosticating new area for the exploration of lead and zinc in Sindesar Khurd area,Rajpura-Dariba belt,Rajsamand district,Rajasthan     

P. K. Yadav  P. C. Avadich 《Journal of the Geological Society of India》2010,75(5):731-738

In the Rajpura-Dariba belt zinc and lead mineralization was established on the basis of gossan and opinions were given that the deposits are stratiform and syngenetic. During last two decades metamorphism and volcanic processes have been attributed for the generation of exhalative and remobilized lead-zinc ore bodies. Subsequent exploration was based on the concept of successive borehole planning around positive intersections. Areas having surface indications of base metal mineralization and their extensions have been already explored. Recent deep drilling by Hindustan Zinc Limited (HZL) in this area has intersected rich ore lodes, thereby confirming depth ward continuity of ore zones at some places. It indicates possibility of searching hidden deposits by innovative techniques. Therefore, today, there is a challenge before geoscientists to discover new deposits in this area by an exploration technique which should have low risk, consume less time and it should be cost effective.  相似文献   

On some properties of prominence eruptions and the associated CMEs in solar cycle 23     

Pooja Gupta  Mohit Gupta  Ruby Yadav  Udit Narain 《Astrophysics and Space Science》2014,352(2):395-402

This work includes a study of some properties such as speed, apparent width, acceleration and latitudes, etc. of all types of Prominence Eruptions (PEs) and the associated Coronal Mass Ejections (CMEs) observed during the period of 1997–2006 by Nobeyama Radioheliograph (NORH) and SOHO/LASCO covering the solar cycle 23. The average speed of prominences and associated CMEs are 51 km/sec and 559 km/sec, respectively. The average angular width is 32^° and 74^°, respectively. As expected the associated CMEs are relatively faster and wider than the prominences.  相似文献   

Study of simultaneous presence of DD and PP electric fields during the geomagnetic storm of November 7–8, 2004 and resultant TEC variation over the Indian Region     

P. Galav  Shweta Sharma  S. S. Rao  B. Veenadhari  T. Nagatsuma  R. Pandey 《Astrophysics and Space Science》2014,350(2):459-469

During very intense geomagnetic storm of November 7–8, 2004 simultaneous presence of storm time disturbance dynamo and eastward and westward directed prompt penetration electric fields inferred from the ground based magnetometer data in the 75^° E sector is presented. Magnetometer observations show that, on the whole, average ΔH variation on 8 November remains below the night time level compared to its quiet day variation. A number of upward and downward excursions have been observed between 0130 UT and 0800 UT in the ΔH variation on 8 November. These excursions in ΔH have been attributed to the episodes of eastward and westward prompt penetrating electric fields. Ionospheric response in the equatorial ionization anomaly region along 75^° E has also been studied using the total electron content data recorded at five GPS stations, namely Udaipur, Bengaluru (IISC), Hyderabad (HYDE), Maldives (MALD) and Diego Garcia (DGAR). Observation of markedly suppressed EIA, in conjunction with ΔH variation which was m negative during the daytime on 8 November, indicates the presence of an external field of opposite polarity (the disturbance dynamo electric field) that either undermined, or overshadowed the daytime ambient (eastward) electric field to the extent that the equatorial plasma fountain could not become effective.  相似文献