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31.
Yaduvanshi Aradhana Kulkarni Ashwini Bendapudi Ramkumar Haldar Kaushik 《Natural Hazards》2020,103(1):685-711
Natural Hazards - The present study examines the spatial and temporal changes in extreme rainfall events (EREs) across the Godavari river basin to develop adaptation strategies for vulnerable... 相似文献
32.
Kaushik Sasmal Eiji Masunaga Adrean Webb Oliver B. Fringer Edward S. Gross Matthew D. Rayson Hidekatsu Yamazaki 《Journal of Oceanography》2018,74(2):169-186
The three-dimensional numerical model SUNTANS is applied to investigate river plume mixing in Otsuchi Bay, an estuary located along the Sanriku Coast of Iwate, Japan. Results from numerical simulations with different idealized forcing scenarios (barotropic tide, baroclinic tide, and diurnal wind) are compared with field observations to diagnose dominant mixing mechanisms. Under the influence of combined barotropic, baroclinic and wind forcing, the model reproduces observed salinity profiles well and achieves a skill score of 0.94. In addition, the model forced by baroclinic internal tides reproduces observed cold-water intrusions in the bay, and barotropic tidal forcing reproduces observed salt wedge dynamics near the river mouths. Near these river mouths, vertically sheared flows are generated due to the interaction of river discharge and tidal elevations. River plume mixing is quantified using vertical salt flux and reveals that mixing near the vicinity of the river mouth, is primarily generated by the barotropic tidal forcing. A 10 ms?1 strong diurnal breeze compared to a 5 ms?1 weak breeze generates higher mixing in the bay. In contrast to the barotropic forcing, internal tidal (baroclinic) effects are the dominant mixing mechanisms away from the river mouths, particularly in the middle of the bay, where a narrow channel strengthens the flow speed. The mixing structure is horizontally asymmetric, with the middle and northern parts exhibiting stronger mixing than the southern part of the bay. This study identifies several mixing hot-spots within the bay and is of great importance for the coastal aquaculture system. 相似文献
33.
Rob Sternberg Egon Lass Eric Marion Kaushik Katari Matthew Holbrook 《Geoarchaeology》1999,14(5):415-439
As part of a program to investigate archaeomagnetic secular variation in Israel and implications for archaeomagnetic dating, we have identified “anomalous” results that have yielded information about site formation processes. Stereonets, vector demagnetization diagrams, and sample location maps are most useful in examining stability of magnetization and consistency of archaeomagnetic directions with each other and with what would be expected from normal secular variation. A collection of examples is presented, including: strong and hard remanence due to vitrification, unstable magnetization due to lightning strikes, superimposed thermal magnetizations, chemical remagnetization, magnetization of a hearth fragment before falling, magnetization of a hot brick after falling, and mechanical deformation of an archaeomagnetic feature. © 1999 John Wiley & Sons, Inc. 相似文献
34.
In high seismic zone regions, slender reinforced concrete structural walls are commonly used in high-rise buildings as a main lateral load resisting element. These walls are very effective in limiting the lateral drift of the building due to their large in-plane stiffness. However, the presence of floor slabs influences the behavior of the shear wall. Also, the current design requirements do not account for the presence of floor slabs. To understand the behavior of wall-slab junctions and address the shortcomings of the current design requirements, the influence of two parameters, namely(a) aspect ratio and(b) longitudinal reinforcement ratio on the behavior is studied numerically. It is observed that the presence of floor slabs at different levels tends to partition the wall into squat wall panels between two consecutive floors. The wall-slab junctions show large stress concentrations arising from the strut action in the squat panels. It is also observed that the floor slabs can get significantly damaged near the wall-slab junction for lower vertical reinforcement ratios in the wall. Thus, the current codeprescribed minimum reinforcement in shear walls is not sufficient and needs to be revisited at for improved performance. 相似文献
35.
Priyabrata Das Kaushik Das Partha Pratim Chakraborty S Balakrishnan 《Journal of Earth System Science》2011,120(2):223-236
Besides offering significant clues towards tracking the geochemical evolution of the mantle and architectural reconstruction
of different ‘supercontinent’, geochronological and geochemical appraisal of igneous inputs are also important to bracket
the depositional time frame of any lithopackage, particularly, the unfossiliferous sedimentary successions. The present study
deals with diabasic intrusive within Mesoproterozoic Saraipalli Formation, which is an argillaceous constituent present at
the basal part of nearly 400 m thick four-tiered unmetamorphosed but deformed sedimentary succession of Singhora Group, Chhattisgarh
Supergroup, central India. The SE–NW trending intrusive comprises mainly of plagioclase and augite together with minor orthopyroxene,
biotite and opaque minerals. Though some plagioclase laths are partially sericitized, the ophitic-to-subophitic texture of
the rock is well preserved. Major and trace element geochemical data indicate that this intrusive is basalt-to-basaltic andesite
in character and of subalkaline basalt affinity. Multi-element plot shows overall LILE-enrichment and enrichment of Pb and
slight depletion of Nb and P, coupled with moderate La/Nb and Th/Nb ratios. Zr, Y and Nb ternary diagrams plot in the fields
of within plate basalt. Selected HFSE ratios indicate a non-plume source with crustal assimilation/sediment mixing. Sm–Nd
and Rb–Sr isotope data show that the intrusive has Srinitial and Ndinitial of 0.709377–0.706672 and 0.510919–0.510815, respectively. Positive ε
t
Nd [t = 1420 Ma] values (+0.3 to + 2.3) indicate depleted isotopic nature of their protolith. The calculated T
DM age is 1.7–1.9 Ga. The mineral-whole rock isochron data (Sm–Nd systematics) of the intrusive implies an emplacement age of
ca. 1420 Ma. Considering synchronous terrain boundary shear zone development in Bastar craton on the southeastern part of
the Singhora basin, mafic magmatism in Eastern Ghats and large-scale basic intrusion in Sausar mobile belt, a major tectono-thermal
event around 1400 Ma is surmised that affected eastern Indian craton. Moreover, geochronology of a bedded porcellanite unit
(ca. 1500 Ma) at the base and a discordant basic intrusive (ca. 1420 Ma) allowed a unique opportunity to qualitatively offer
an upper bound of time bracket for the deposition of Saraipalli Formation, i.e., ∼80 Ma. 相似文献
36.
D. Deb K. N. R. Kaushik B. H. Choi C. H. Ryu Y. B. Jung C. Sunwoo 《Geotechnical and Geological Engineering》2011,29(4):419-429
In Pasir mine, coal seams and host rocks of varying thickness have been uniquely deposited with an average dip angle of 85°.
The host rocks are weak and mainly composed of mudstone and sandstone comprising of 90–95% of the total pit volume. The thickness
of coal seams and host rocks ranges from sub-metric to few tenths of meter. The overall safe pit slope angle was evaluated
to be 27° for mining depth of 50–150 m. Several slopes failure incidents have occurred in the mine causing considerable disruption
in production and monetary loss. It is envisaged that slope failures may be triggered due to blasting conducted in steeply
dipping stratified deposit. In order to investigate the causes of slope failures, peak particle velocity (PPV) and accelerations
at various locations from the blast site have been measured. In addition, finite element models of pit slope have been analyzed
by applying static or gravity loading as well as blasting or dynamic loading. This paper elaborates the results of in situ
measurements of ground vibration and numerical investigation and suggests possible causes of slope failures in Pasir mine. 相似文献
37.
Rock excavation is carried out either by drilling and blasting or using rock-cutting machines like rippers, bucket wheel excavators,
surface miners, road headers etc. Economics of mechanised rock excavation by rock-cutting machines largely depends on the
achieved production rates. Thus, assessment of the performance (productivity) is important prior to deploying a rock-cutting
machine. In doing so, several researchers have classified rockmass in different ways and have developed cuttability indices
to correlate machine performance directly. However, most of these indices were developed to assess the performance of road
headers/tunnel-boring machines apart from a few that were developed in the earlier days when the ripper was a popular excavating
equipment. Presently, around 400 surface miners are in operation around the world amongst which, 105 are in India. Until now,
no rockmass classification system is available to assess the performance of surface miners. Surface miners are being deployed
largely on trial and error basis or based on the performance charts provided by the manufacturer. In this context, it is logical
to establish a suitable cuttability index to predict the performance of surface miners. In this present paper, the existing
cuttability indices are reviewed and a new cuttability indexes proposed. A new relationship is also developed to predict the
output from surface miners using the proposed cuttability index. 相似文献
38.
By‐products of various industrial fermentations can be good adsorbents for removing hazardous dyes from wastewater. However, after biosorption, regeneration of biomass is essential to minimize the solid waste generation or else the dye laden biomass should be suitably disposed off. In the present work, experiments were conducted on the Acid Navy Blue and Methylene Blue dyes which were biosorbed to the fungal biomass (strain closely related to Aspergillus lentulus) produced on corncob as the substrate through solid state fermentation. In order to dispose the dye laden biomass, it was vermicomposted along with cow dung (CD) employing Eisenia fetida. Results indicated that the dye laden biomass was not lethal toward the earthworms as no mortality was observed. However, as compared with control experiments (where dye laden biomass was absent), the reproductive potential of the earthworms was affected. Nevertheless, further investigations on optimization of biomass and CD ratios can facilitate vermicomposting as a potential route for disposing dye laden biomass. 相似文献
39.
Nonlinear dust ion acoustic solitary waves (DIASW) in dusty plasma are studied incorporating kinematic viscosity, using Sagdeev’s pseudopotential approach. The effects of kinematic viscosity and the nonextensive parameter q on the features of DIASW are investigated in some detail. 相似文献
40.
Kaushik Roy Prasanta Chatterjee S. S. Kausik C. S. Wong 《Astrophysics and Space Science》2014,350(2):599-605
The dust-acoustic shock waves have been theoretically investigated using reductive perturbation technique. An unmagnetized four-component dusty plasma system consisting of nonextensive q-distributed electrons, Boltzmann distributed ions, and negatively as well as positively charged dust particles has been considered. The solution of Burgers equation in planar geometry is numerically analyzed. It has been observed that the nonextensive q-distribution of electrons has a significant role in the formation of shock waves. The relevance of our results to astrophysics as well as laboratory plasmas are briefly discussed. 相似文献