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Elasto-plastic fatigue crack growth analysis of plane problems in the presence of flaws using XFEM

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Frontiers of Structural and Civil Engineering 2015年第4期9卷 420-440页

作者： sachin kumar A.S. SHEDBALE I. V. SINGH B.K. MISHRA Department of Mechanical and Industrial Engineering Indian institute of Technology Roorkee Roorkee 247667 India

In this paper, elasto-plastic XFEM simulations have been performed to evaluate the fatigue life of plane crack problems in the presence of various defects. The stress-strain response of the material is modeled by Ramberg-Osgood equation. The von-Mises failure criterion has been used with isotropic hardening. The -integral for two fracture modes (mode-I and mode-II) is obtained by decomposing the displacement and stress fields into their symmetric and antisymmetric parts, then individual stress intensity factors are extracted from -integral. The fatigue life obtained by EPFM is found quite close to that obtained by LEFM.

关键词： XFEM von-Mises yield criterion isotropic hardening fatigue crack growth J-integral

Graphene sandwiched crumb rubber dispersed hot mix asphalt

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Journal of Traffic and Transportation Engineering(English Edition) 2020年第5期7卷 652-667页

作者： Bineet Baliyar Singh Fanismita Mohanty Sudhanshu Sekhar das Sarat kumar Siuain Department of Civil Engineering Veer Surendra Sai University of TechnologyBurla 768018India Department of Chemistry Veer Surendra Sai University of TechnologyBurla 768018India

The crumb rubber obtained from discarded vehicle tires and graphene oxide prepared by oxidation of graphite powder in laboratory were used to modify virgin bitumen. Four different hot mix asphalt matrices prepared using virgin bitumen, crumb rubber modified bitumen, graphene oxide modified bitumen and combination of crumb rubber-graphene oxide modified bitumen are compared. The modified bitumen matrices are characterised by Fourier transform infrared spectroscopy and scanning electron microscopy for structural and morphological analysis. Marshall properties along with indirect tensile test and tensile strength ratio tests were carried out to check the resistance towards cracking and moisture susceptibility of matrices. The results show that, crumb rubber and graphene oxide are completely compatible with bitumen. 9.8% crumb rubber content in crumb rubber modified bitumen hot mix asphalt exhibits the optimum result. The performance of graphene oxide modified bitumen hot mix asphalt exhibits superior performance in comparison to control mix and crumb rubber modified bitumen hot mix asphalt *** enhanced properties of modified bitumen hot mix asphalt with the combining effect of graphene oxide and crumb rubber, are suitable for road construction.

关键词： Hot mix asphalt Crumb rubber Graphene oxide Modified bitumen

Galaxy Interactions in Filaments and Sheets:Insights from EAGLE Simulations

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Research in Astronomy and Astrophysics 2023年第11期23卷 161-168页

作者： Apashanka das biswajit Pandey Suman Sarkar Department of Physics Visva-Bharati UniversitySantiniketanBirbhum731235India Department of Physics Indian Institute of Science Education and Research TirupatiTirupati-517507India Department of Physics Indian Institute of Technology KharagpurKharagpur721302India

We study the color and star formation rates of paired galaxies in filaments and sheets using the EAGLE *** find that the major pairs with pair separation50 kpc)in filaments are on average redder and low-star-forming compared to those embedded in *** galaxies in filaments and sheets may have different stellar mass and cold gas mass *** a KS test,we find that for paired galaxies with pair separation<50 kpc,there are no significant differences in these properties in sheets and *** filaments transport gas toward the cluster of *** earlier studies find preferential alignment of galaxy pairs with the filament *** alignment of galaxy pairs may lead to different gas accretion efficiency in galaxies residing in filaments and *** propose that the enhancement of star formation rate at smaller pair separation in filaments is caused by the alignment of galaxy pairs.A recent study with SDSS data reports the same *** confirmation of these results by the EAGLE simulations suggests that the hydrodynamical simulations are powerful theoretical tools for studying galaxy formation and evolution in the cosmic web.

关键词： methods:data analysis methods:statistical galaxies:evolution galaxies:interactions (cosmology:)large-scale structure of universe

Do Minor Interactions Trigger Star Formation in Galaxy Pairs?

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天文和天体物理学研究:英文版 2023年第9期23卷 322-340页

作者： Apashanka das biswajit Pandey Suman Sarkar Department of Physics Visva-Bharati UniversitySantiniketanBirbhum731235India Department of Physics Indian Institute of Science Education and Research TirupatiTirupati517507India Department of Physics Indian Institute of Technology KharagpurKharagpur721302India

We analyze the galaxy pairs in a set of volume limited samples from the Sloan Digital Sky Survey to study the effects of minor interactions on the star formation rate(SFR)and color of *** carefully design control samples of isolated galaxies by matching the stellar mass and redshift of the minor *** SFR distributions and color distributions in the minor pairs differ from their controls at>99%significance *** also simultaneously match the control galaxies in stellar mass,redshift and local density to assess the role of the *** null hypothesis can be rejected at>99%confidence level even after matching the *** analysis shows a quenching in the minor pairs where the degree of quenching decreases with the increasing pair separation and plateaus beyond 50 *** also prepare a sample of minor pairs with Hαline *** calculate the SFR of these galaxies using the Hαline and repeat our *** observe a quenching in the Hαsample *** find that the majority of the minor pairs are quiescent systems that could be quenched due to minor *** data from the Galaxy Zoo and Galaxy Zoo 2,we find that only∼1%galaxies have a dominant bulge,4%–7%galaxies host a bar and 5%–10%of galaxies show active galactic nucleus(AGN)activity in minor *** indicates that the presence of bulge,bar or AGN activity plays an insignificant role in quenching the galaxies in minor *** more massive companion satisfies the criteria for mass quenching in most of the minor *** propose that the stripping and starvation likely caused the quenching in the less massive companion at a later stage of evolution.

关键词： methods statistical-galaxies formation-methods data analysis-galaxies interactions-galaxies star formation-(cosmology )large-scale structure of universe

Population status and regeneration of a tropical clumping bamboo Schizostachyum dullooa under two management regimes

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Journal of Forestry Research 2011年第1期22卷 43-46页

作者： Arun Jyoti Nath Ashesh kumar das Department of Ecology and Environmental Science Assam University Silchar 788011 Assam India

Schizostachyum dullooa （Gamble） Majumder ＇dolu bamboo＇ is a thin walled sympodial moderate sized to large tufted bamboo, dominant in the successional fallows of northeast India. The impact of resource management on productivity and sustainability of the species was evaluated by investigating the population status and regeneration in Cachar tropical semi evergreen forest under private property resource management （PPRM） and common property resource management （CPRM） regimes. Population status revealed current-year, one-year, two-year and three-year-old culms contribute 54%, 24%, 16% and 6% of the total culms per clump, respectively, under PPRM. Three-year-old culms were absent in CPRM and population status was thus represented by current year （83%）, one-year （16%） and two-year （1%） old culms. Net change, rate of change and % gain in population for different age classes showed the prevalence of management practices under CPRM was unscientific. Efficiency of new culm production per clump used as an index of regeneration was 69.7% in PPRM and 59.88% in CPRM. New culms produced under CPRM were small and thin. We conclude that CPRM is inappropriate for a long term economic and ecological sustainability of the species and alternative management protocols are needed for conservation of the species.

关键词： management regime population structure production efficiency Schizostachyum dullooa

Machining of circular micro holes by electrochemical micro-machining process

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Advances in Manufacturing 2013年第4期1卷 314-319页

作者： Alok kumar das P. Saha Alokkumardas·ParthaSaha Indian School of Mines Dhanbad Jharkhand India Indian Institute of Technology Kharagpur KharagpurWest Bengal India

Machining of micro holes with micro electro- chemical machining （micro ECM） process has been carried out with an indigenously developed set up. This paper describes relevant problems and solutions for the circular micro holes machining process on 304 stainless steel sheets with 60 μm thickness using high speed steel cylindrical tool of diameter 500 ~tm and using dilute I-I2SO4 as elec- trolyte. The taper angle variation of the machined hole is analyzed and reported for different experimental setting parameters. The minimum value of the taper angle of machined holes is achieved at the parameter setting of 0.4 mol/L H2504, 700 kHz, 600 ns and 21 V, for stainless steel sheets and HSS tool.

关键词： Micro machining - Micro ECMMicro-hole ~ Electrochemical dissolution ~Short pulse voltage ~ Pulse power supply

Process optimization of benzo[ghi]perylene biodegradation by yeast consortium in presence of ZnO nanoparticles and produced biosurfactant using Box-Behnken design

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Frontiers in Biology 2018年第6期13卷 418-424页

作者： Sanjeeb kumar Mandal Nupur Ojha Nilanjana das Bioremediation Laboratory Department of Bio-Medieal SciencesSchool of Bio Sciences and TechnologyVIT (Vellore Institute of Technology)Vellore-632014Tamil NaduIndia

Benzo[ghi]perylene (BghiP), a polycyclic aromatic hydrocarbon (PAH) containing six fused benzene rings is considered as priority pollutant because of its carcinogenicity, mutagenicity and acute toxicity. The synthesis of ZnO nanoparticles was done following the standard method. Biosurfactant production by yeast consortium YC04 in MSM was confirmed by various tests viz. drop collapse test, methylene blue agar plate method and emulsification test (E24) using the standard procedures. Efficiency of YC04 was tested to remediate BghiP in presence of ZnO nanoparticles and produced biosurfactant in the growth medium. Response surface methodology (RSM), 3-level five variables Box-Behnken design (BBD) was employed to optimize the factors viz. pH 7.0, temperature 30°C, shaking speed 130 rpm, inoculum dosage 3% and ZnO nanoparticles concentration 2 g/L after a period of 6 days of incubation for the enhanced degradation of BghiP (63.83±0.01%). It was well in close agreement with the predicated value obtained by RSM model yield (63.83±0.08%). Analysis of variance (ANOVA) showed F-value of 51.70, R2 of 0.9764, probability of<0.0001 and coefficient of variation of 1.25% confirmed the validity of the model. Degradation of BghiP was assessed using GC-MS and FTIR analysis. Kinetic study demonstrated that BghiP degradation fitted first order kinetic model. To the best of our knowledge, this is the first report on process optimization toward nanobioremediation of BghiP using yeast consortium in presence of ZnO nanoparticles and produced biosurfactant in medium.

关键词： biodegradation bioremediation optimization pollutants yeasts

Aggregate dust model to study the polarization properties of comet C/1996 B2 Hyakutake

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Research in Astronomy and Astrophysics 2010年第4期10卷 355-362页

作者： Himadri Sekhar das Abinash Suklabaidya Saonli Datta Majumder Asoke kumar Sen Department of Physics Assam University

The observed linear polarization data of comet Hyakutake are studied at wavelengths λ=0.365 μm,λ=0.485 μm and 0.684μm through simulations using Ballistic Particle-Cluster Aggregate and Ballistic Cluster-Cluster Aggregate aggregates of 128 spherical *** first found that the size parameter of the monomer,x ～ 1.56-1.70,turned out to be the most suitable which provides the best fits to the observed dust scattering properties at three wavelengths：λ=0.365 μm,0.485μm and 0.684μ***,the effective radius of the aggregate （r） lies in the range 0.45 μm ≤ r ≤ 0.49 μm at λ=0.365 μm;0.60 μm ≤ r ≤ 0.66 μm at λ=0.485 μm and 0.88 μm ≤ r ≤ 0.94 μm at λ=0.684 μ*** using superposition T-MATRIX code and the power-law size distribution,n（r）～ r-3,the best-fitting values of complex refractive indices are calculated for the observed polarization data at the above three *** best-fitting complex refractive indices （n,k） are found to be （1.745,0.095） at λ=0.365 μm,（1.743,0.100） at λ=0.485 μm and （1.695,0.100） at λ=0.684 μ*** refractive indices derived from the present analysis correspond to a mixture of both silicates and organics,which are in good agreement with the in situ measurement of comets by different spacecraft.

关键词： comets:general - dust extinction - scattering - polarization

Insecticide resistance in Indian Anopheles: A stumbling block for malaria elimination

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Asian Pacific Journal of Tropical Medicine 2020年第10期13卷 429-430页

作者： Nikhat Khan Ashok kumar Mishra Aparup das Division of Vector Borne Diseases ICMR-National Institute of Research in Tribal HealthNIRTH CampusGarhaJabalpurMadhya Pradesh482003India

Malaria is a mosquito-borne disease caused by protozoan parasites of Plasmodium genus,inflicting health of human living in tropical and subtropical regions of the globe since time immemorial.

关键词： Malaria Plasmodium Indian