Quantification of stability improvement of a dump through biological reclamation     

S. K. Chaulya  R. S. Singh  M. K. Chakraborty  B. K. Srivastava 《Geotechnical and Geological Engineering》2000,18(3):193-207

An integrated study on biological stabilisation of a dump slope has indicated that biological reclamation with grass and tree species should be considered for long term stability of this coal mine dump in India. The grasses have greater soil binding capacity and help to control soil erosion and improve dump stability. Native grasses such as Bamboo (Dendrocalmus strictus) and Kashi (Saccharum spontaneum) are the important constituents of grass species which can stabilise the dump slopes. Field observation of growth performance of grasses have indicated that mean grass height, root depth and below-ground root biomass are 185 cm (±68), 45 cm (±5) and 467 g m^–2 (±170), respectively after three years of grass growth on Mudidih overburden dump slope in India. The growth performance of tree species, namely Sisum (Dalbergia sisoo) and Subabool (Leucena lecocephala), in terms of height, diameter increment, below-ground biomass and root depth have shown mean values of 219 cm (±94), 48 mm (±6), 4.0 kg m^–2 (±1.5) and 1 m (±0.1), respectively. This acts as biological fertility which helps in root proliferation and enhancement of dump stability. From the numerical modelling it is suggested that roots of these grass and tree species have significantly enhanced the factor of safety of dump from 1.4 to 1.8 and therefore have a positive role in maintaining long term stability.  相似文献   

Gravitational Field of Domain Walls in Higher Dimension     

Subenoy Chakraborty  Farook Rahaman  Lalit Biswas 《Astrophysics and Space Science》2000,274(4):851-858

In this paper, we study the gravitational field of domain wall in fivedimensional space-time. Exact solutions of Einstein's equations for a scalarfield with a potential V(Ø) are presented, describing thegravitational field of plane symmetric domain walls. The solution showsthat the energy density as well as pressure in the perpendicular directionon both sides of the walls to be reflection symmetric with respect to thewalls.PACS numbers: 98.80 cq, 0450  相似文献   

Gutter casts from the Proterozoic Bijaygarh Shale Formation,India: Their implication for storm-induced circulation in shelf settings     

Chandan Chakraborty 《Geological Journal》1995,30(1):69-78

The orientations of elongate gutter casts occurring in inner shelf storm deposits of the Proterozoic Bijaygarh Shale Formation, India reveal a modal population oriented roughly parallel to the average trend of the associated wave ripples. Assuming that the wave ripple trend approximately represents the orientation of the contemporary shoreline, the shore-parallel gutters appear to have been formed by the geostrophic current. Some gutters oriented at high angles to the inferred shoreline presumably represent incision by wave orbital currents in a storm-induced combined flow regime. The gutters also show variations in the style of incision and infill, which may be useful in distinguishing between gutters formed by wave orbital and geostrophic currents, independently of their orientation pattern with respect to the palaeo-shoreline.  相似文献   

Seafloor Geomorphology and Processes on the Western Continental Margin of India based on Multibeam Acoustic Backscatter Data Analysis     

Sumanta Dandapath  Andrew Menezes  Bishwajit Chakraborty  John Kurian  Koppella N. Prudhvi Raju 《Marine Geodesy》2018,41(2):177-200

An assessment of the multibeam sonar data of the central Western Continental Margins of India has been carried out to evaluate the seafloor geomorphology and processes by examining the geomorphological attributes e.g., slope, sediments, structures, etc. associated with geomorphic features. The variation in relief and the features located in the region have been mapped and interpreted collectively by utilizing several geospatial mapping tools. The backscatter strength across the area, apparently congruent with the local relief, has helped to examine the sediment movement on the seafloor. The prominent features found in the region include faults, pockmarks, mounds, submarine terraces, and submerged fossil reefs. Several areas with varying topography engender comparable fractal dimension at short scale breaks, and the probability density functions (PDFs) utilizing backscatter data depicting overlapping classes. The present study highlights how fractals and scale break parameters can be utilized to determine the seafloor processes and associated sedimentological dynamics in a complex geographical environment with strong bottom currents, seasonal upwelling, and faulted structure. The role and impact of the various geomorphic processes on the reworking of sediment movement and the overall progression of the seafloor morphology has been revealed for the first time in this part of the ocean bottom.  相似文献   

Effect of Stellar Wind and Poynting–Robertson Drag on Photogravitational Elliptic Restricted Three Body Problem     

A. Chakraborty  A. Narayan 《Solar System Research》2018,52(2):168-179

The existence and linear stability of the planar equilibrium points for photogravitational elliptical restricted three body problem is investigated in this paper. Assuming that the primaries, one of which is radiating are rotating in an elliptical orbit around their common center of mass. The effect of the radiation pressure, forces due to stellar wind and Poynting–Robertson drag on the dust particles are considered. The location of the five equilibrium points are found using analytical methods. It is observed that the collinear equilibrium points L₁, L₂ and L₃ do not lie on the line joining the primaries but are shifted along the y-coordinate. The instability of the libration points due to the presence of the drag forces is demonstrated by Lyapunov’s first method of stability.  相似文献   

Land use/land cover dynamics in Umngot watershed of Meghalaya using geospatial tools     

K. Chakraborty  P. K. Joshi  K. K. Sarma 《Journal of the Indian Society of Remote Sensing》2009,37(1):99-106

Meghalaya is a landlocked state where the progress of industrialization is very slow. Majority of the population (rural) depends on agriculture. Agriculture in the state is carried on in primitive ways with Jhumming prevailing in many parts. This practice is considered destructive as vast forest areas are cleared and burnt. Such areas are used for cultivation and left out. After a gap of few years (2–3 years as of now and 15–20 years in past) the area is revisited for cultivation without allowing to rejuvenate. The present work provides a status and trend of Land use land cover dynamics in parts (at watershed level) of Meghalaya. The geospatial tools have been used to assess (a) the changes in land use land cover since 1970s to 2005; (b) patch dynamics for understanding the degree of fragmentation; (c) changes along the terrain topography. Umngot watershed of Meghalaya is taken as experimental area, which is a representative of mid-altitudinal watershed particularly in the Jaintia hills district of Meghalaya.  相似文献   

Advances in understanding of the mechanism for generation of earthquake thermal precursors detected by satellites     

Arun K. Saraf  Vineeta Rawat  Swapnamita Choudhury  Sudipta Dasgupta  Josodhir Das 《International Journal of Applied Earth Observation and Geoinformation》2009

Stresses building up during an earthquake preparation phase also manifest themselves in the form of a so called increased land surface temperature (LST) leading to a thermal precursor prior to the earthquake event. This phenomenon has now been validated by our observations of short-term thermal anomalies detected by infrared satellite sensors for several recent past earthquakes around the world. The rise in infrared radiance temperature was seen to vary between 5 and 12 °C for different earthquakes. We discuss in this paper different explanations for the generation of such anomalies that have been offered. Emission of gases due to the opening and closure of micropores upon induced stresses and also the participation of ground water have been propounded as a possible cause for generation of thermal anomalies. Seismo-ionosphere coupling, by which gases like radon move to the earth–atmosphere interface and cause air ionization thus bringing about a change in air temperature, relative humidity, etc., has been put forth by some workers. A mechanism of low frequency electromagnetic emission was tested and experimented by scientists with rock masses in stressed conditions as those that exist at tectonic locations. The workers proposed the positive hole pair theory, which received support from several scientific groups. Positive holes (sites of electron deficiency) are activated in stressed rocks from pre-existing yet dormant positive hole pairs (PHPs) and their recombination at rock–air interface leads to a LST rise. A combination of remote sensing detection of rock mechanics behavior with a perception of chemistry and geophysics has been applied to propose the remote sensing rock mechanics theory. Remote sensing detections of such anomalies confirm so far proposed lab theories for such a hotly debated field as earthquake precursor study by providing unbiased observations with consistency in time and space distribution.  相似文献   

Analysis of pile subjected to torsion in multi‐layered soil     

A. Misra  Rajni Saggu  D. Basu  T. Chakraborty 《国际地质力学数值与分析法杂志》2014,38(5):475-492

A new method of analysis of piles in multi‐layered elastic soil subjected to a torque at the head is developed. The differential equation governing the angle of twist in the pile is derived using the variational principles of mechanics. The method of initial parameters is used to obtain closed‐form solutions of the angle of twist and torque in the pile as a function of depth. The inputs required for the analysis are shear moduli of pile and soil, pile geometry and thickness of soil layers. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Higher-order gravity in anR 1×S 1×S 2 space-time     

S. Chakraborty 《Astrophysics and Space Science》1992,187(1):135-141

The action with general Lagrangian is transformed to the canonical form. The classical field equations are analysed for a particular choice of the Lagrangian. A study of the Wheeler-Dewitt equation has also been performed.  相似文献   

Pattern of sedimentation during the Late Paleozoic,Gondwanaland glaciation: An example from the Talchir Formation,Satpura Gondwana basin,central India   总被引：2，自引：0，他引：2  

Chandan Chakraborty  Sanjoy Kumar Ghosh 《Journal of Earth System Science》2008,117(4):499-519

  相似文献