Electrical conductivity of a spinel lherzolite and a garnet peridotite to 1550°C: relevance to the effects of partial melting     

M. H. Manghnani  C. S. Rai 《Bulletin of Volcanology》1978,41(4):328-332

Electrical conductivity σ of two ultramafic rocks (a spinel lherzolite and a garnet peridotite) has been investigated to melting temperature at 1 bar under known oxygen fugacity environment. The electrical conductivity of the two rocks is found to increase with degree of partial melting and an ～ 15% melt fraction is necessary for the electrical conductivity to increase by ～ 1 order of magnitude. For a given melt fraction electrical conductivity of a spinel lherzolite is lower than that of a garnet peridotite and may be attributed to the differences in the composition of the melts formed.  相似文献   

Laboratory Studies of the Flow of Some Organic Solvents and Their Aqueous Solutions Through Bentonite and Kaolin Clays     

A. S. Abdul  T. L. Gibson  D. N. Rai 《Ground water》1990,28(4):524-533

  相似文献   

Bridging the gap or broadening the problem?     

Harinarayan Tiwari  Subash Pd. Rai  Kumari Shivangi 《Natural Hazards》2016,80(1):351-365

  相似文献   

Variation of Rayleigh wave group velocity dispersion and seismic heterogeneity of the Indian crust and uppermost mantle     

S. Mitra  K. Priestley  V. K. Gaur  S. S. Rai  J. Haines 《Geophysical Journal International》2006,164(1):88-98

  相似文献   

Signatures of rift environment in the production of garnet-amphibolites and eclogites from Tso-Morari region, Ladakh, India: A geochemical study     

D. Rameshwar Rao  Hakim Rai 《Gondwana Research》2006,9(4):512-523

The geochemistry of eclogites and garnet-amphibolites from Tso-Morari region, Ladakh, India has been investigated to characterize their protoliths on the basis of immobile elements, especially trace elements including REE. The eclogites and garnet-amphibolites have coherent compositions, except for the UHP metamorphic minerals being preserved in eclogites. Compositionally, the metabasites range from ‘depleted’ to ‘enriched’, and span from within-plate basalts (WPB) to MORB fields, and match with various enriched or ‘transitional’ MORB types (e.g., on Ti–Zr–Y and Nb–Zr–Y ternary plots). Isotopically they have Sr_i ratio 0.706 which is similar to some of the Ocean Island Basalt (OIB). The rocks under study suggest that the enriched components are probably derived by melting of a mantle source with an enriched OIB-type component rather than due to the crustal contamination. We propose a rift environment for their protoliths and relate to advanced intra-continental rift situation. Furthermore, our geochemical studies envisage an initial phase of plume activity (Cambrian or earlier) resulting in basaltic magma in the eclogitic layers at sub-lithospheric levels, wherein they were subjected to crystallization under ultra-high pressure conditions. At a later stage the reactivation of faults (probably during Permo-Triassic times) acted as channels for the emplacement of the high pressure rocks in the continental crust. Subsequently, the ultra-high pressure rocks got re-equilibrated as amphibolites, with some remaining as relict eclogites, which later got exposed to the surface during various phases of the Himalayan uplift.  相似文献   

Effect of Nickel and Cadmium on Ammonium Uptake Kinetics of Free and Immobilized Cells of Anacystis nidulans     

Mamta Awasthi  Lal Chand Rai 《洁净——土壤、空气、水》2004,32(2):149-153

The stress effect of Ni and Cd on the ammonium uptake varied significantly (ANOVA test) in free and immobilized state of the test organism. The effect due to the interaction between different variables (cell state type, metal type and metal dose) was studied to depict the significant or non‐significant variation in the ammonium uptake by free and immobilized cells in the presence of metal ions. Ammonium uptake exhibited a competitive mode of inhibition in the presence of Ni in both free and immobilized state of the organism. However, Cd exhibited non‐competitive and competitive inhibition in free and immobilized cells, respectively. The study demonstrates that there is a considerable influence of metal ions on the ammonium uptake. Cd was found to be more toxic compared to Ni in both free and immobilized state.  相似文献   

Modifications in aerosol physical,optical and radiative properties during heavy aerosol events over Dushanbe,Central Asia     

Dipesh Rupakheti  Maheswar Rupakheti  Xiufeng Yin  Julian Hofer  Mukesh Rai  Yuling Hu  Sabur F.Abdullaev  Shichang Kang 《地学前缘(英文版)》2021,12(6):299-312

The location of Central Asia,almost at the center of the global dust belt region,makes it susceptible for dust events.The studies on atmospheric impact of dust over the region are very limited despite the large area occupied by the region and its proximity to the mountain regions(Tianshan,Hindu Kush-Karakoram-Himalayas,and Tibetan Plateau).In this study,we analyse and explain the modification in aerosols'phys-ical,optical and radiative properties during various levels of aerosol loading observed over Central Asia utilizing the data collected during 2010-2018 at the AERONET station in Dushanbe,Tajikistan.Aerosol epi-sodes were classified as strong anthropogenic,strong dust and extreme dust.The mean aerosol optical depth(AOD)during these three types of events was observed a factor of～3,3.5 and 6.6,respectively,higher than the mean AOD for the period 2010-2018.The corresponding mean fine-mode fraction was 0.94,0.20 and 0.16,respectively,clearly indicating the dominance of fine-mode anthropogenic aerosol during the first type of events,whereas coarse-mode dust aerosol dominated during the other two types of events.This was corroborated by the relationships among various aerosol parameters(AOD vs.AE,and EAE vs.AAE,SSA and RRI).The mean aerosol radiative forcing(ARF)at the top of the atmosphere(ARFTOA),the bottom of the atmosphere(ARFBOA),and in the atmosphere(ARFATM)were-35±7,-73±16,and 38±17 Wm-2 during strong anthropogenic events,-48±12,-85±24,and 37±15 Wm-2 during strong dust event,and-68±19,-117±38,and 49±21 Wm-2 during extreme dust events.Increase in aerosol loading enhanced the aerosol-induced atmospheric heating rate to 0.5-1.6 K day-1(strong anthropogenic events),0.4-1.9 K day-1(strong dust events)and 0.8-2.7 K day 1(extreme dust events).The source regions of air masses to Dushanbe during the onset of such events are also identified.Our study con-tributes to the understanding of dust and anthropogenic aerosols,in particular the extreme events and their disproportionally high radiative impacts over Central Asia.  相似文献   

Reuse of Distillery Wastewater with Designed Dose and Pattern for Sugarcane Irrigation     

Jaspal S. Chauhan  Jai Prakash Narayan Rai 《洁净——土壤、空气、水》2012,40(8):838-843

The present investigation aims to optimize dose and pattern of distillery effluent for sugarcane irrigation. The postmethanated distillery effluent (PMDE) was recorded to have significant amount of micro‐ (Na, Zn, Fe) and macro‐ (Ca, Mg, N‐NO₃, P, K, S–SO) nutrients and so was utilized for sugarcane irrigation. Lysimetric studies were conducted to assess the impact of PMDE on sugarcane productivity with different concentrations (50 and 75%) and irrigation patterns (intermittent and pre‐sowing). The intermittent pattern of ferti‐irrigation with 50 and 75% effluent dose for sugarcane crop was found to enhance the growth and quality parameters of crop without impairing the groundwater quality. Results were more pronounced with 75% intermittent irrigation as the percent increase with respect to control for plant length, cane girth, cane weight, number of internodes per cane, dry matter accumulation, juice extraction, sucrose content, and available sugar were 28.0, 42.5, 14.6, 40.2, 54.4, 18.9, 44.9, 57.9, and 50.0%, respectively. It is suggested that PMDE can be used as an alternative of fresh water irrigation and also as a fertilizer for sugarcane, provided that the effluent quality and sugarcane quality is continuously monitored to avoid any contamination.  相似文献   

Seismic strengthening of RC columns using external steel cage     

Pasala Nagaprasad  Dipti Ranjan Sahoo  Durgesh C. Rai 《地震工程与结构动力学》2009,38(14):1563-1586

Steel caging technique is commonly used for the seismic strengthening of reinforced concrete (RC) columns of rectangular cross‐section. The steel cage consists of angle sections placed at corners and held together by battens at intervals along the height. In the present study, a rational design method is developed to proportion the steel cage considering its confinement effect on the column concrete. An experimental study was carried out to verify the effectiveness of the proposed design method and detailing of steel cage battens within potential plastic hinge regions. One ordinary RC column and two strengthened columns were investigated experimentally under constant axial compressive load and gradually increasing reversed cyclic lateral displacements. Both strengthened columns showed excellent behavior in terms of flexural strength, lateral stiffness, energy dissipation and ductility due to the external confinement of the column concrete. The proposed model for confinement effect due to steel cage reasonably predicted moment capacities of the strengthened sections, which matched with the observed experimental values. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Determination of the particle load based on detailed suspended sediment measurements at a hydropower plant     

Anant Kumar Rai  Arun Kumar 《国际泥沙研究》2019,34(5):409-421

Suspended sediment particles contained in inflows of water systems of hydropower plants (HPPs) cause hydro-abrasive erosion of the hydraulic turbines and structures leading to significant maintenance costs, efficiency reductions, and downtime. Relevant parameters such as suspended sediment concentration (SSC), particle size distribution (PSD), shape, and mineralogical composition were measured with an online multi-frequency acoustic instrument and based on manually taken samples from the end of the sand trap of the Toss HPP in the Himalayan region, India. In the laboratory, the samples were analyzed using the gravimetric method, laser diffraction, turbidity, dynamic digital image processing, scanning electron microscope, petrography analysis, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The online instrument and the samples provided measurement results at a single point. To investigate vertical gradients in concentration and particle sizes, additional samples were collected 9 times at 7 relative water depths. The SSC, most particle sizes, and particle shape were found to be evenly distributed over depth except d90, i.e. the diameter which is not exceeded by 90% of the particle mass. d90 measured at 76% of the water depth was in the range of fine sand and was multiplied by 1.05 to obtain an average value representative for the entire depth. Improved methodologies to quantify both particle shape and size in an analytical model for hydro-abrasive erosion are proposed. Also, the PSD measuring performance of laser diffraction and dynamic imaging was studied and similar values of the median particle sizes were obtained from both instruments. Further, multi-frequency acoustic, turbidity and laser diffraction techniques were found suitable for SSC measurement at the test case HPP.  相似文献