Utilization of Basic Oxygen Furnace (BOF) slag in the production of a hydraulic cement binder     

A. Srinivasa Reddy  R.K. Pradhan  Sanjay Chandra 《International Journal of Mineral Processing》2006

Basic Oxygen Furnace (BOF) slag is a major waste product generated during the steelmaking process. In India and in most industrial countries, the use of BOF slag as a road ballast and land filler has had a very long history. This being a low end use, a study was conducted to examine the possibility of converting the slag into a hydraulic binder. This paper describes the effect of cooling rate on mineralogy and cementing characteristics of normal BOF slag as well as iron oxide-devoid BOF slag. Specifically, the mineralogy and compressive strengths of heat-treated slags were compared with a conventional ordinary Portland cement. It was found that the slowly cooled slags did not show any cementing properties. The iron oxide-devoid slag, on slow cooling, disintegrated into fine powder. The water-cured cubic specimens of quenched slag products were tested for their compressive strengths. The cementing properties of the quenched slag products were improved by formation of hydraulic phases and showed considerable strength after 28 days of water curing.  相似文献   

Excitation equilibrium for low lying levels in Cii,Niii, Oiv,Nevi, Mgviii,Six, and Siii     

Suresh Chandra 《Solar physics》1978,58(2):291-297

The populations of the excited state ² P _3/2 relative to the ground state ² P _1/2 have been investigated in C ii, N iii, O iv, Ne vi, Mg viii, Si x, and Si ii by considering all the radiative and collisional processes including the collisional transitions to the higher states which cascade to the upper level. The relative populations are used for the calculation of the line emissivities. The intensities of 76 320, 30 258 and 14 302 lines of Nevi, Mgviii, and Six ions respectively in the chromosphere-corona transition region are also calculated.  相似文献   

Cometary impacts and ice-ages     

Fred Hoyle  Chandra Wickramasinghe 《Astrophysics and Space Science》2001,275(4):367-376

Cycles of glaciation with an average period of 100 kyr are mediatedby impacts of cometary bolides. Ice-age conditions are dry and dusty withlow rates of precipitation. Comets in the mass range 10¹⁵ -10¹⁶ gimpacting the oceans could release enough water vapour into the atmosphereto enhance a depleted greenhouse effect. The energy deposited in the oceanswould also warm the surface layers, thus starting up anevaporation-precipitation cycle which ushers in warmer interglacialinterludes. The latter have neutral stability and are necessarilyshort-lived, eventually drifting back to glacial conditions on timescalesof 10 kyr.  相似文献   

GEOLOGICAL STUDIES OF METAMORPHIC ROCKS IN THE VICINITY OF M.C.T./LESSER HIMALAYAN SHEAR ZONE, PARTS OF SIKKIM HIMALAYAS     

Chandra Shekhar Dubey 《地学前缘》2000,(Z1)

GEOLOGICAL STUDIES OF METAMORPHIC ROCKS IN THE VICINITY OF M.C.T./LESSER HIMALAYAN SHEAR ZONE, PARTS OF SIKKIM HIMALAYAS  相似文献   

Geological Studies of Metamorphic Rocks in the Vicinity of M. C. T./Lesser Himslayan Shear zone, Parts of Sikkim Himalayas     

Chandra Shekhar Dubey 《地学前缘》2000,(Z1)

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Performance evaluation of soil mixtures treated with graphite and used as barrier fill material for high-level radioactive waste repository     

Liu  Xiaoyan  Congress  Surya Sarat Chandra  Cai  Guojun  Liu  Songyu 《Acta Geotechnica》2021,16(5):1487-1507

Buffer/backfill material is an important engineering barrier in a deep geological repository of high-level radioactive waste (HLW). Its thermo-hydro-mechanical (THM) performance is very important for the safe and stable operation of the HLW repository system. Natural graphite powder mixed with sodium bentonite forms a buffer/backfill material that can dissipate heat quickly and provide strong isolation. In this paper, the THM characteristics of bentonite–sand–graphite–polypropylene fiber (BSGF) mixtures, used as a buffer/backfill material, were studied through a series of laboratory tests. The influence of graphite and polypropylene fiber contents on thermal conductivity, swelling pressure, hydraulic conductivity, and strength properties of BSGF mixtures with different sand contents was analyzed. Experimental results indicated that the graphite content, the maximum graphite mesh number, and the initial dry density of bentonite–graphite mixtures influenced the thermal conductivity of bentonite–graphite mixtures. The addition of polypropylene fiber was found to enhance the shear strength and inhibit cracking without significantly affecting the expansivity, permeability, and thermal conductivity of the BSGF mixtures. This study provides a new buffer/backfill material that can improve the stability, functionality, and thermal efficiency of the HLW repository.

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Analysis of Families of Triple Close Approaches Occurring inStellar Systems in Three Dimensions (II)     

Navin Chandra  K.B. Bhatnagar 《Astrophysics and Space Science》2000,271(4):395-422

This is the second paper of a trilogy dealing with the role of triple encounters with low initial velocities and equal masses in the evolution of stellar systems in three dimensional space. It shows how a condition of complete collapse may be perturbed to obtain well-established families of asymmetric triple close approaches with systematic regularity of escape with the formation of a binary. The main result is that when perturbation is introduced two close approaches called the first close approach and the second close approach occur in the same plane but the binary formed and the escaper are not in that plane. Further it is observed that the conjecture of Szebehely (1977) viz. `The measure of escaping orbits is significantly higher than the measure of stable orbits' is likely to be true. The third and last paper offers applications in stellar systems. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Spectral analysis of wind and temperature components during lightning in pre-monsoon season over Ranchi     

Arun K. Dwivedi  Sagarika Chandra  Manoj Kumar  Sanjay Kumar  N. V. P. Kiran Kumar 《Meteorology and Atmospheric Physics》2015,127(1):95-105

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http://www.sciencedirect.com/science/article/pii/S1674987114000899     

C.Manikyamba  Sohini Ganguly  M.Santosh  Abhishek Saha  G.Lakshminarayana 《地学前缘(英文版)》2015,6(3):437-451

The Rajahmundry Trap Basalts（RTB） are erupted through fault-controlled fissures in the Krishna-Godavari Basin（K-G Basin） of Godavari Triple Junction,occurring as a unique outcrop sandwiched between Cretaceous and Tertiary sediments along the east coast of India.Detailed geochemical studies have revealed that RTB are mid-Ti（1.74-1.92） to high-Ti（2.04-2.81） basalts with a distinct quartz tholeiitic parentage.MgO（6.2-13.12 wt.%）,Mg^#（29-50） and Zr（109-202 ppm） suggest that these basalts evolved by fractional crystallization during the ascent of the parent magma along deep-seated fractures.Moderate to high fractionation of HREE,as indicated by（Gd/Yb）N ratios（1.71-2.31） of RTB,suggest their generation through 3-5%melting of a Fe-rich mantle corresponding to the stability fields of spinel and garnet peridotite at depths of 60-100 km.Low K₂O/P₂O₅（0.26-1.26）,high TiO₂/P₂O₅（6.74-16.79）,La/Nb（0.89-1.45）,Nb/Th > 8（8.35-13）,negative anomalies at Rb reflect minimum contamination by granitic continental crust.（Nb/La）_PM ratios（0.66-1.1） of RTB are attributed to endogenic contamination resulted through recycling of subducted oceanic slab into the mantle.Pronounced Ba enrichment with relative depletion in Rb indicates assimilation of Infra- and Inter-trappean sediments of estuarine to shallow marine character.Geochemical compositions such as Al₂O₃/TiO₂（3.88-6.83）,medium to high TiO₂（1.74-2.81 wt.%）.positive Nb anomalies and LREE enrichment of these RTB attest to their mantle plume origin and indicate the generation of parent magma from a plume-related enriched mantle source with EM 1signature.Ba/Th（46-247）,Ba/La（3.96-28.51） and Th/Nb（0.08-0.13） ratios suggest that the source enrichment process was marked by recycling of subduction-processed oceanic crust and lithospheric components into the mantle.Zr/Hf（37-41） and Zr/Ba（0.51-3.24） indicate involvement of an asthenospheric mantle source.The Rajahmundry basalts show affinity towards FOZO（focal zone mantle） and PSCL（post-Archaean subcontinental lithosphere） which reflect mixing between asthenospheric and lithospheric mantle components in their source.Origin of RTB magma is attributed to plume-lithosphere interaction and the upward movement of melt is facilitated by intrabasinal deep-seated faults in the K-G Basin.  相似文献   

Long-term historic changes in climatic variables of Betwa Basin,India   总被引：2，自引：1，他引：1  

Shakti Suryavanshi  Ashish Pandey  Umesh Chandra Chaube  Nitin Joshi 《Theoretical and Applied Climatology》2014,117(3-4):403-418

In this study, trend analyses of historic past climatic variables were investigated for the Betwa basin located in Central India. In the serially independent climatic variables, Mann–Kendall test (MK test) was applied to the original sample data. However, in the serially correlated series, pre-whitening is used before employing the MK test. The long-term trend analysis showed several of the meteorological stations to exhibit a decreasing trend in annual and seasonal precipitation in the study area. Seasonal and yearly numbers of rainy days are decreased. However, onset of effective monsoon (except for Shivpuri and Tikamgarh stations) did not show any trend during the study period. For maximum temperature, five out of 12 stations showed a decreasing trend in monsoon season whereas almost all other stations showed an increasing trend in winter and no trend in summer season. For minimum temperature, only two stations of the basin showed a decreasing trend in monsoon and all other stations exhibited a significant increase in winter and summer season. The increase of winter temperature may adversely affect the growth of Rabi crop (wheat and mustard) in the study area. Potential evopotranspiration (PET) did not show any trend in monsoon, except for Jalaun and Jhansi stations, showing decreasing trends. Raisen and Vidisha stations showed an increasing trend in winter only, and the trend for other stations were random in nature. In summer, five out of 12 stations showed an increasing trend in PET. Results of this study can be employed in preparation of water resources development and management plan in the Betwa Basin.  相似文献