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Assessment of the role of slit as a safety valve in failure of levees

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International Journal of Sediment Research 2008年第4期23卷 361-375页

作者： C.S.p.OJHA V.p.singh d.d.AdRIAN department of Civil Engineering Indian Institute of TechnologyRoorkee Uttaranchal 247667 IndiaProf. Caroline and William N. Lehrer distinguished Chair in Water Engineering Professor of Civil & Environmental Engineering and Professor of Biological and Agricultural Engineering Texas A & M University2117 TAMU Dept. of Biological & Agric. Engineering 321 Scoates Hall College Station Texas 77843-2117 USA department of Civil and Environmental Engineering Louisiana State UniversityBaton Rouge LA 70803-6405 U. S. A.Rubicon Professor

The development of a narrow channel or slit due to piping just underneath the base of levees channel has been reported to be useful to withstand the increase in the head beyond critical head conditions. Also, the maximum slit length has been emphasized to be up to half of the base width. By developing a model of critical head considering slit, it is found that the critical head can increase with the development of slit length only under certain conditions. Analysis of piping failure data indicates that the critical head expressions considering slit length constitute a potentially useful model for critical head.

关键词： Failure of levee piping Flood defense Water head seepage erosion

distilling physical origins of hardness in multi-principal element alloys directly from ensemble neural network models

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npj Computational Materials 2022年第1期8卷 1450-1460页

作者： d.Beniwal p.singh S.Gupta M.J.Kramer d.d.Johnson p.K.Ray Metallurgical&Materials Engineering Indian Institute of Technology RoparRupnagar140001PunjabIndia Ames Laboratory US Department of EnergyAmesIA50011USA Materials Science&Engineering Iowa State UniversityAmesIA50011USA

despite a plethora of data being generated on the mechanical behavior of multi-principal element alloys,a systematic assessment remains inaccessible via Edisonian *** approach this challenge by considering the specific case of alloy hardness,and present a machine-learning framework that captures the essential physical features contributing to hardness and allows high-throughput exploration of multi-dimensional compositional *** model,tested on diverse datasets,was used to explore and successfully predict hardness in Al_(x)Ti_(y)(CrFeNi)_(1-x-y),Hf_(x)Co_(y)(CrFeNi)_(1-x-y)and Al_(x)(TiZrHf)_(1-x)systems supported by data from density-functional theory predicted phase stability and ordering *** experimental validation of hardness was done on *** selected systems pose diverse challenges due to the presence of ordering and clustering pairs,as well as vacancy-stabilized novel *** also present a detailed model analysis that integrates local partial-dependencies with a compositional-stimulus and model-response study to derive material-specific insights from the decision-making process.

关键词： alloys alloy element

Strength and deformation characteristics of steel fibrous concrete beams

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Journal of Zhejiang University-Science A(Applied physics & Engineering) 2007年第2期8卷 257-263页

作者： singh Bhupinder singh S.p. KAUSHIK S.K department of Civil Engineering Indian Institute of Technology Roorkee 247 667 India department of Civil Engineering National Institute of Technology Jalandhar 144 011 India

The results of an analytical investigation of the flexural behaviour of Steel Fibre Reinforced Concrete （SFRC） beams are presented. The complete response of the SFRC beams under displacement controlled static loading was obtained using nonlinear Finite Element （FE） techniques implemented with the help of ATENA 2d soRware. Issues relating to the behaviour of SFRC which have a direct bearing on the FE modelling are discussed with relevance to the software employed for the nonlinear analysis. Constitutive models amenable to numerical analysis for steel fibrous concrete are presented. The structural response throughout the loading regime was captured in terms of the load-deflection behaviour, which in addition to the post-peak response characterized the failure mode of the test beams. The crack patterns at crack initiation and at the end of the tests were also recorded. Experimental results from the specimens of two other investigators were used as control values for this investigation. The response of the specimens of this investigation was evaluated in terms of initial tangent stiffness, peak loads and toughness. Good match was obtained between the results from this investigation and corresponding experimentally obtained values, wherever available. The influence of the fibre content is reflected in the observed trends in peak loads, deflection at peak loads and toughness, which are in broad agreement with known behavioral patterns of SFRC.

关键词： Analysis deformation Strength Steel Fibre Reinforced Concrete (SFRC) Toughness

petrographic characteristics coals, Mahanadi Gondwana and paleomires of Mand-Raigarh Basin, Chhattisgarh, India

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International Journal of Coal Science & Technology 2016年第2期3卷 165-183页

作者： A. S. Naik M. p. singh N. Volkmann p. K. singh d. Mohantya d. Kumar Banaras Hindu University Varanasi India T U Bergakademie Freiberg Germany CSIR-Central Institute of Mining and Fuel Researchdhanbad India

Mand-Raigarh coalfield is one of the largest coalfields in the Mahanadi basin. The Geological Survey of India carried out initial study primarily on exploration. However, detailed petrographic and geochemical characters of the coals have not been done so far. This investigation is an attempt for petrographic and geochemical appraisal of the coals. Moreover, effort is also made for possible interpretation on development of coal facies. The results drawn from 30 composite coal samples suggest coals are rich in vitrinite, with collotelinite as the dominant maceral while liptinite macerals register low concentration. dominant mineral assemblages found were clay minerals, pyrite was recorded as disseminated, framboidal and euhedral forms, carbonates recorded were mainly siderites. The vitrinite reflectance random （VRo） mean values range from 0.44 % to 0.56 %, and the rank of coal is suggested as high volatile ＇B＇ to ＇A＇ sub- bituminous in rank. The rock-eval pyrolysis reveal TOC content varying from 37 % to 68.83 %, while low hydrocarbon generating potential is evident from low $2 and Tmax values. The Hydrogen Index （HI） versus Oxygen Index （OI） plot reveal that the samples belong to Kerogen type--II-III with input dominantly from terrestrial source, some samples also fall in Kerogen type--II domain indicating lacustrine input. Vitrinite reflectance result indicate that the samples are immature and approaching oil window, which is in agreement with data of the Rock-Eval parameters. The gelification index （GI） and tissue preservation index （TpI） indicate that the coal developed in a telematic set up with high tree density. The ground water index （GWI） and vegetation index （VI） demonstrate that the peat developed as an ombrogenous bog.

关键词： Mand-Raigarh coalfield Organic petrology Geochemistry Source rock

Rib stability: A way forward for safe coal extraction in India

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International Journal of Mining Science and Technology 2017年第6期27卷 1087-1091页

作者： singh Satyendra K. Agrawal Harshit singh Awanindra p. Mining Methods and design Simulation Research Group CSIR-Central Institute of Mining and Fuel Research (CSIR-CIMFR) Dhanbad 826015 India

Ensuring rib stability during pillar extraction is of prime importance in bord and pillar(B&p) method of underground coal mining with caving. Rib stability has been assessed here by way of assessing factor of safety(FOS), a ratio of the strength of rib to stress on it. Earlier formulations for rib stability when applied to case studies gave very low FOS value suggesting significant ground control problems, which were contrary to the field observations. This has necessitated the need to revisit the concept of rib stability. The stress coming on the rib is estimated with the use of numerical modeling technique using the FLAC^(3d) software. The methodology of assessing rib-stability with the help of suggested rib-strength formulation has been validated at eight Indian coal mines. The outcome of this study finds relevance and importance in ensuring underground coal liquidation with improved safety and conservation.

关键词： Rib stress estimation Rib-strength Rib-stability Numerical modeling Bord & pillar method Underground coal extraction

Effect of electroslag remelting and homogenization on hydrogen flaking in AMS-4340 ultra-high-strength steels

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 611-621页

作者： Shivraj singh Kasana O.p.pandey School of physics and Materials Science Thapar Institute of Engineering and Technology Star Wire (India) Ltd.Ballabgarh

Hydrogen flakes and elemental segregation are the main causes of steel rejection. To eliminate hydrogen flaking, the present study focuses on the manufacture of AMS-4340 ultra-high-strength steel through an alternate route. AMS-4340 was prepared using three different processing routes. The primary processing route consisted of melting in an electric arc furnace, refining in a ladle refining furnace, and vacuum degassing. After primary processing, the heat processes(d1, d2, and d3) were cast into cylindrical electrodes. For secondary processing, electroslag remelting(ESR) was carried out on the primary heats to obtain four secondary heats: E1, E2, E3, and E4. Homogenization of ingots E1, E2, E3, and E4 was carried out at 1220°C for 14, 12, 12, and 30 h, respectively, followed by an antiflaking treatment at 680°C and air cooling. In addition, the semi-finished ESR ingot E4 was again homogenized at 1220°C for 6–8 h and a second antiflaking treatment was performed at 680°C for 130 h followed by air cooling. The chemical segregation of each heat was monitored through a spectroscopy technique. The least segregation was observed for heat E4. Macrostructure examination revealed the presence of hydrogen flakes in heats E1, E2, and E3, whereas no hydrogen flakes were observed in heat E4. Ultrasonic testing revealed no internal defects in heat E4, whereas internal defects were observed in the other heats. A grain size investigation revealed a finer grain size for E4 compared with those for the other heats. Steel produced in heat E4 also exhibited superior mechanical properties. Therefore, the processing route used for heat E4 can be used to manufacture an AMS-4340 ultra-high-strength steel with superior properties compared with those of AMS-4340 prepared by the other investigated routes.

关键词： AMS-4340 steel segregation and homogenization antiflaking treatment electroslag remelting

Thermal inertia at the MSL and InSight mission sites on Mars

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Earth and planetary physics 2022年第1期6卷 18-27页

作者： d.singh S.Uttam Centre of Studies in Resources Engineering Indian Institute of Technology BombayMumbaiIndia physical Research Laboratory AhmedabadIndia

For planetary surface materials,thermal inertia is the critical property that governs the surface’s daily thermal response and controls diurnal and seasonal surface temperature *** we use the ground measurements made by the MSL Curiosity rover and the InSight lander to determine the thermal inertia of two sites on *** study compares the variation of thermal inertia during and after the Large dust Storm(LdS)of Martian Year(MY)*** determine surface thermal inertia,we derive a simple approximation(using energy balance),which utilizes surface albedo,surface energy flux,and diurnal change in the surface *** average thermal inertia in MY34 is about 39.2%,3.7%,and 3.4%higher than MY35 average thermal inertia for the MSL,InSight(FOV1),and InSight(FOV2),***,the thermal inertia at the InSight(FOV1)is consistently lower by about 20 J·m^(-2)·s^(-1/2)·K^(-1) than the InSight(FOV2)site for all scenarios,indicating variation in the region’s surface *** best-fit surface albedo in MY34(determined using the KRC model)are about 0.08,0.05,and 0.03 higher than MY35 surface albedo for the MSL,InSight(FOV1),and InSight(FOV2),*** increase in both surface albedo and thermal inertia during the LdS indicates that the underlying surface is both more thermally resistant and more reflective than the overlying loose dust.

关键词： Mars Mars surface thermal inertia dust storm Mars climate

Seasonal variability in CdOM absorption and fluorescence properties in the Barataria Basin,Louisiana,USA

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Journal of Environmental Sciences 2010年第10期22卷 1481-1490页

作者： Shatrughan singh Eurico d'Sa Erick Swenson department of Oceanography and Coastal Sciences Louisiana State University

Absorption and fluorescence properties of chromophoric dissolved organic matter （CdOM） along a 124 km transect in the Barataria Basin, a large estuary located in Louisiana, USA, were investigated during high and low flow periods of the Mississippi River in the spring and winter of 2008-2009. Mean CdOM absorption at 355 nm from the marine to the freshwater end member stations ranged from （3.25 ± 0.56） to （20.76 ± 2.43） m^-1 for the three month high flow period whereas it varied from （1.48 ± 1.08） to （25.45 ± 7.03） m^-1 for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and shelf exchanges in the lower basin and precipitation and runoff in the upper basin. An inverse relationship of CdOM absorbance and fluorescence with salinity observed in the basin could he a useful indicator of salinity. CdOM fluorescence also varied over a large range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons. Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak, lowest the T-peak, and the C and M-peaks showing similar trends along the transect. during low flow season the A/C ratio were well correlated with station locations indicating increased terrestrial influence towards the upper basin. CdOM absorption and fluorescence at 355 nm were highly correlated and independent of CdOM sources suggesting that fluorescence could be used to characterize CdOM in the basin.

关键词： Barataria Basin chromophoric dissolved organic matter CdOM fluorescence excitation-emission matrix

Microstructure and mechanical properties of friction welded carbon steel(EN24) and nickel-based superalloy(IN718)

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International Journal of Minerals,Metallurgy and Materials 2021年第1期28卷 111-119页

作者： V.T.Gaikwad M.K.Mishra V.d.Hiwarkar R.K.p.singh Kalyani Centre for Technology and Innovation Bharat Forge LimitedPune 411036India department of Materials Engineering Defense Institute of Advance TechnologyPune 411025India

Continuous-drive rotary friction welding was performed to join cylindrical specimens of carbon steel(EN24) and nickel-based superalloy(IN718), and the microstructures of three distinct weld zones—the weld interface(WI)/thermo-mechanically affected zone(TMAZ),the heat-affected zone(HAZ), and the base metal—were *** joint was observed to be free of defects but featured uneven flash *** backscatter diffraction(EBSd) analysis showed substantial changes in high-angle grain boundaries, low-angle grain boundaries, and twin boundaries in the TMAZ and ***, significant refinement in grain size(2 –5 μm) was observed at the WI/TMAZ with reference to the base *** possible causes of these are *** microhardness profile across the welded joint shows variation in *** changes in hardness are ascribed to grain refinement, phase transformation, and the dissolution of strengthening *** tensile test results reveal that a joint efficiency of 100% can be achieved using this method.

关键词： friction welding dissimilar metals EN24 IN718 microstructure mechanical properties