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Sources and dynamics of sedimentary organic matter in Sundarban mangrove estuary from Indo-Gangetic delta

Ecological Processes 2017年第1期6卷 69-83页

作者： m.Bala krishna Prasad Alok Kumar A.L.Ramanathan Dilip Kumar Datta 22616 Shining Harness Street ClarksburgMD 20871USA School of Environmental Sciences Jawaharlal Nehru UniversityNew Delhi 110067India Environmental Science Discipline Khulna UniversityKhulna 9208Bangladesh

Introduction:mangrove forests are highly productive ecosystems distributed along the tropical coast *** biogeochemistry of mangroves are primarly driven by both allochthonous and autochthonous *** of organic matter in coastal ecosystems enables to understand the biogeochemical transformation of organic matter and its influence on ecosystem productivity in response to various changing environmental ***,the elemental and stable carbon and nitrogen levels were employed to understand the organic matter(Om)dynamics in the Sundarban mangrove ecosystem(India-Bangladesh).Results:Differences in stable isotope values indicate that variable sources influence the Om dynamics in Sundarban *** progressive enrichment inδ13C levels along the land-coastal continuum indicates that the terrestrial and marine inputs are dominant at the landward and seaward ends,*** CuO oxidationderived lignin phenol monomers describe significant levels of total lignin are preserved in Sundarban mangrove sediments during *** phenol monomer ratios are lower than the plant litter explaining that aromatic ring cleavage is the dominant mechanism for the lignin ***,the Ad/Al ratios were higher than the plant litter explaining the oxidation of propyl side chain of vascular Om influencing the carbon cycling in Sundarban ***,the Ad/Al ratios describe the vascular Om degradation is through the oxidation of propyl side ***:The regional variability in land-use regulates the spatial variability in C,N,OC/TN ratio,δ13C andδ15N between the Indian and the Bangladesh Sundarban mangroves and indicates that in the upstream terrestrial organic matter and/or mangrove plant litter contribute significant amount of organic matter,whereas the marine POC influences the organic matter dynamics in *** three end-member mixing model applying terrestrial plant litter,seston,and marine POC as e

关键词： Sundarban mangrove Organic carbon Stable isotopes Lignin phenols Three end-member mixing model

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mathematical modelling on phase based transmissibility of Coronavirus

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Infectious Disease modelling 2020年第1期5卷 375-385页

作者： m.Veera krishna J.Prakash Department of mathematics Rayalaseema UniversityKurnoolAndhra Pradesh518007India Department of mechanical Engineering Science Faculty of Engineering and the Built EnvironmentUniversity of JohannesburgAuckland Park Kingsway CampusJohannesburgSouth Africa

mathematical and epidemiological simulation plays a pivotal role in predicting,anticipating,and controlling present and future *** better understand and model the dynamics of a specific infection,researchers need to consider the influence of many variables ranging from micro-hostepathogen interactions to host-to-host encounters,and the prevailing cultural,social,economic,and local customs *** reported by the WHO,a novel corona virus(COVID-19)is identified as the etiological virus through Wuhan pneumonia for unknown etiology with Chinese administration on Jan 7,*** virus is designated as an unsympathetic SARS-Cov-2 by International Commission for Taxonomy of Viruses on Feb 11,*** main aim is to enlarge a phase based mathematical modelling to specify the transferability of this *** is developed Reservoir-individuals spreading set of connections modelling for imitating the prospective broadcast as of the infectivity foundation in the direction of the person *** view of the fact that,the Reservoir has set of connections to rigid to see the sights obviously as well as communal anxieties are concentrating on top of the spreading starting reservoir to *** subsequent generation matrix methodology is endorsed towards compute the fundamental reproduction number(R0)through the RP modelling to measure the transferability by the *** values of R0 are estimated from reservoir to human being as well as starting individual to individual,that is to say,the accepted quantity of less important diseases this consequence from presenting a solitary contaminated personality addicted to differently susceptible *** present model demonstrated that the spreading of COVID-19 is superior to the middle-East pulmonary infirmity during the middle-East nationals,analogous to harsh sensitive pulmonary infirmity,but inferior than middle-East pulmonary infirmity within the Republic of *** can also extend this study to

关键词： COVID-19 Corona virus Phase based model Next generation matrix Reproduction number Virus spread

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Achieving higher strength in Cu–Ag–Zr alloy by warm/hot rolling

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Rare metals 2017年第4期36卷 263-267页

作者： S. Chenna krishna Abhay K. Jha Bhanu Pant Koshy m. George materials and mechanical Entity Vikram Sarabhai Space Centre Trivandrum 695022 India

High-strength Cu-3Ag-0.5Zr alloy plates were produced by multi-pass rolling in the temperature range of 500-800 ℃. An increase in strength was observed by rolling in the aforementioned range without significant loss in ductility. All the rolled samples show higher strength than solution-treated and aged samples. The maximum strength was observed for plates rolled at 500 ℃ with a yield strength and ultimate tensile strength of 311 and 385 mPa, respectively, and retaining a ductility of 23 %. Transmission electron microscopy （TEm） studies showed uniform distribution of fine silver precipitates and high dislocation density in the rolled samples. Nevertheless, the size of precipitates and dislocation density varied with the rolling temperature. The superior strength achieved in the rolled samples is attributed to grain refinement, dislocation strengthening, and precipitation hardening. This method can be employed to produce high-strength plates of pre- cipitation hardenable copper alloys.

关键词： Warm/hot rolling Higher strength Copperalloy Strengthening

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Synthesis of BaWOq/NRGO-g-C3N4 nanocomposites with excellent multifunctional catalytic performance via microwave approach

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Frontiers of materials Science 2018年第3期12卷 247-263页

作者： m. mohamed Jaffer SADIQ U. Sandhya SHENOY D. krishna BHAT Department of Chemistry National Institute of Technology Karnataka Surathkal Mangalore-575025 India Department of Chemistry College of Engineering and Technology Srinivas University Mukka Mangalore-574146 India

Novel barium tungstate/nitrogen-doped reduced graphene oxide-graphi- tic carbon nitride （BaWO4/NRGO-g-C3N4） nanocomposite has been synthesized by a simple one-pot microwave technique. The synthesized nanocomposites are well characterized by diffraction, microscopic and spectroscopic techniques to study its crystal structure, elemental composition, morphological features and optical properties. The material prepared is tested for its performance as an electrocatalyst, photocatalyst and reduction catalyst. The nanocomposite catalyzed the photodegradation of methylene blue （mB） dye in 120 min, reduction of 4-nitro phenol （4-NP） to 4-amino phenol （4-AP） in 60 s, showed an impressive Tafel slope of 62 mV/dec for hydrogen evolution reaction （HER）. The observed results suggest that the nanocomposite acts as an efficient multifunctional catalyst. The reported approach provides fundamental insights which can be extended to other metal tungstate-based ternary composites for applications in the field of clean energy and environment in the future.

关键词： BaWO4/NRGO-g-C3N4 nanocomposites microwave irradiation hydrogen evolution reaction photocatalyst reduction

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Improvement in hot corrosion resistance of dissimilar alloy 825 and AISI 321 CO2-laser weldment by HVOF coating in aggressive salt environment at 900℃

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International Journal of minerals,metallurgy and materials 2020年第11期27卷 1536-1550页

作者： S.m.muthu m.Arivarasu T.Hari krishna Supriyo Ganguly K.V.Phani Prabhakar Saurav mohanty School of mechanical Engineering Vellore Institute of TechnologyVelloreTamil Nadu 632014India Center for Innovative manufacture Research Vellore Institute of TechnologyVelloreTamil Nadu 632014India Welding Engineering and Laser Processing Centre Cranfield UniversityBedfordUnited Kingdom CLPm International Advanced Research Centre for Powder Metallurgy&New Materials(ARCI)HyderabadIndia Department of mechanical Engineering North Carolina State UniversityRaleighUSA

This study investigated the hot corrosion performance of a dissimilar weldment of Ni-based superalloy and stainless steel joined by CO2-laser welding and improved by high-velocity oxy-fuel(HVOF)coating in a Na2SO4-60wt%V2O5 environment at 900℃.A dissimilar butt joint of AISI 321 and alloy 825 was fabricated by CO2-laser welding with low heat input after obtaining the optimum welding parameters by bead-on-plate *** metallurgical and mechanical properties of the laser weldment were *** tensile test results indicated the occurrence of fracture in the base metal AISI 321 *** HVOF process was employed to coat Ni-20wt%Cr on the *** evaluate the surface morphology of the corrosion products formed on the uncoated and Ni-20wt%Cr-coated weldments,scanning electron microscopy(SEm)analysis was ***-dispersive spectroscopy(EDS)was used to determine the different elements present on the surface *** existence of oxide phases on the weldments was determined by X-ray diffraction(XRD).The cross sections of the weldments were characterized by SEm with EDS line mapping *** results indicated that the Ni-20wt%Cr-coated weldment exhibited superior hot corrosion resistance due to the development of Cr2O3 and NiCr2O4 protective oxide scales.

关键词： nickel-based superalloy dissimilar welding weldment corrosion high-velocity oxy-fuel coating corrosion kinetics

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Perturbations in Earth’s Atmosphere over An Indian Region during the Total Solar Eclipse on 22 July 2009

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Journal of meteorological Research 2019年第4期33卷 784-796页

作者： S.B.Surendra PRASAD Vinay KUmAR K.krishna REDDY S.K.DHAKA Shristy mALIK m.Venkatarami REDDY U.murali krishna Semi-arid-zone Atmospheric Research Centre(SARC) Department of PhysicsYogi Vemana UniversityKadapaAndhra Pradesh 516003India Radio and Atmospheric Physics Lab Rajdhani CollegeUniversity of DelhiDelhi 110015India Department of Applied Physics Delhi Technical UniversityDelhi 110042India

During a total solar eclipse(TSE)on 22 July 2009,atmospheric perturbations were monitored from the surface to thermosphere to understand TSE’s impact on the meteorological(temperature,relative humidity,wind speed,and wind direction)and chemical(O3 and NOx)parameters around Kadapa(14.28°N,78.42°E),a tropical semi-arid region of *** this purpose,an experiment was conducted at Yogi Vemana University Campus,Kadapa,India,to measure the temperature,wind speed,wind direction,and concentrations of ozone(O3),NO,NO2,and NOx by using the automatic weather station(AWS)and O3 *** the eclipse day(22 July 2009),the surface observations at Kadapa showed a reduction in temperature(about 1.1℃)because of the solar *** of the thermal,dynamical(wind),and chemical parameters on the TSE day with control days[preceding(21 July 2009)and succeeding(23 July 2009)the TSE]illustrated the influence of solar *** the eclipse period,the O3 mixing ratio decreased,while NO2 and NOx increased;however,NO remained *** addition,radio occultation(RO)temperature profiles from Constellation Observing System for meteorology,Ionosphere,and Climate(COSmIC)/Formosat Satellite mission(FORmOSAT-3)and Thermosphere,Ionosphere,and mesosphere Energetics and Dynamics(TImED)satellites were utilized to understand the impact of TSE on dynamics of the middle and upper atmosphere from tropopause to the *** vertical resolution COSmIC observations revealed that during the solar eclipse,tropopause was cooler with twin peaks(double tropopause).The lower thermosphere between 110 and 130 km became warmer during the TSE,which might be caused by the dynamical response of the atmosphere in this region to the solar *** experimental data have provided very fine-scale variations of the atmospheric parameters both in time and height and also constituted a new set of results on TSE for further research.

关键词： total solar eclipse (TSE) atmospheric perturbations tropopause dynamics COSmIC/FORmOSAT-3satellite radio occultation (RO) observations

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Analysis of unlined pressure shafts and tunnels of selected Norwegian hydropower projects

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Journal of Rock mechanics and Geotechnical Engineering 2018年第3期10卷 486-512页

作者： Chhatra Bahadur Basnet krishna Kanta Panthi Department of Geoscience and Petroleum Norwegian University of Science and Technology

Norwegian hydropower industry has more than 100 years of experiences in constructing more than4000 km-long unlined pressure shafts and tunnels with maximum static head of 1047 m（equivalent to almost 10.5 mPa） reached at unlined pressure tunnel of Nye Tyin project. Experiences gained from construction and operation of these unlined pressure shafts and tunnels were the foundation to develop design criteria and principles applied in Norway and some other countries. In addition to the confinement criteria, Norwegian state-of-the-art design principle for unlined pressure shaft and tunnel is that the minor principal stress at the location of unlined pressure shaft or tunnel should be more than the water pressure in the shaft or tunnel. This condition of the minor principal stress is prerequisite for the hydraulic jacking/splitting not to occur through joints and fractures in rock mass. Another common problem in unlined pressure shafts and tunnels is water leakage through hydraulically splitted joints or pre-existing open joints. This article reviews some of the first attempts of the use of unlined pressure shaft and tunnel concepts in Norway, highlights major failure cases and two successful cases of significance, applies Norwegian criteria to the cases and reviews and evaluates triggering factors for *** article further evaluates detailed engineering geology of failure cases and also assesses common geological features that could have aggravated the failure. The minor principal stress is investigated and quantified along unlined shaft and tunnel alignment of six selected project cases by using threedimensional numerical model. Furthermore, conditions of failure through pre-existing open joints by hydraulic jacking and leakage are assessed by using two-dimensional fluid flow analysis. Finally, both favorable and unfavorable ground conditions required for the applicability of Norwegian confinement criteria in locating the unlined pressure shafts and tunnels for ge

关键词： Hydropower projects Unlined pressure shafts and tunnels minor principal stress Hydraulic jacking Water leakage

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Investigations of Soret,Joule and Hall effects on mHD rotating mixed convective flow past an infinite vertical porous plate

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Journal of Ocean Engineering and Science 2019年第3期4卷 263-275页

作者： m.Veera krishna B.V.Swarnalathamma Ali J.Chamkha Department of mathematics Rayalaseema UniversityKurnoolAndhra Pradesh 518007India Department of Science and Humanities Stanley College of Engineering&Technology for WomenAbidsHyderabadTelangana 500001India Department of mechanical Engineering Prince Sultan Endowment for Energy and EnvironmentPrince Mohammad Bin Fahd UniversityAl-Khobar 31952Saudi Arabia RAK Research and Innovation Center American University of Ras Al Khaimah10021United Arab Emirates

We made an elaborate scrutiny on the Soret and Joule effects of mHD mixed convective flow of an incompressible and electrically conducting viscous fluid past an infinite vertical porous plate taking Hall effects into *** technique is used to solve the non-dimensional *** effects of the various non-dimensional parameters on velocity,temperature and concentration within the boundary layer are *** that,computational deliberations or discussions are also undertaken on the effects of the pertinent or significant parameters on the skin-friction coefficient and rates of heat and mass transfer in terms of the Nusselt and Sherwood numbers *** concentration distribution increases with increase in Soret effect and decrease with increase in chemical reaction *** increase in Prandtl number results to decrease the temperature *** the primary and secondary velocity components and temperature increases with increasing heat source *** friction coefficient decreases with an increase in permeability parameter,whereas it shows reverse effect for thermal and mass Grashof *** number increases with an increase in Prandtl *** number reduces with increasing Soret number.

关键词： Hall effects Soret number Porous medium Joules dissipation Chemical reaction

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Rock-like behavior of biocemented sand treated under non-sterile environment and various treatment conditions

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Journal of Rock mechanics and Geotechnical Engineering 2021年第3期13卷 705-716页

作者： meghna Sharma Neelima Satyam.krishna RReddy Discipline of Civil Engineering Indian Institute of Technology IndoreIndore453552India Department of Civil Materialsand Environmental EngineeringUniversity of Illinois at ChicagoChicagoILUSA

microbially induced calcite precipitation(mICP)is a recently developed technique for microbiological ground improvement that has been applied for mitigating various geotechnical ***,the major challenges,such as calcite precipitation uniformity,presence of different bacteria,cementation solution optimization for cost reduction,and implementation under non-sterile and uncontrolled field environment are still not fully explored and require detailed investigation before field *** study aims to address these challenges of mICP to improve the geotechnical properties of sandy *** series of experiments were conducted using poorly graded Narmada River(India)sand,which were subjected to various biotreatment schemes and tested for unconfined compressive strength(UCS),split tensile strength(STS),ultrasonic pulse velocity(UPV),hydraulic conductivity(after 6 d,12 d,and 18 d of treatment),and calcite *** microstructure of sand was examined through a scanning electron microscope(SEm).Initially,the sand was individually augmented with two non-pathogenic bacterial strains,***(S.)pasteurii and Bacillus(B.)*** stopped-flow injection method was adopted to provide cementation solutions at three different durations(treatment cycle)of 12 h,24 h,and 48 h and three different pore volumes(PVs)of 1,0.75,and *** pore volume here refers to the porosity which is expressed as a ratio,i.e.a porosity of 50%was used as *** results showed rock-like behaviors of biocemented sand with the UCS,STS,and UPV enhancement up to 2333 kPa,437 kPa,and 2670 m/s,*** hydraulic conductivity reduction of 96.6%was achieved by 12%of calcite formation after 18 d of treatment using Sporosarcina pasteurii,12-h treatment cycle,and one pore volume of cementation media in each ***,a 24-h treatment cycle and 0.5-pore volume cementation solution were found to be the optimal treatment which was effective and economical to achiev

关键词： Bacteria microbially induced calcite precipitation (mICP) Soil stabilization microstructure Calcite content

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On the spatio-temporal variation in b-value after 25 April 2015 Gorkha,Nepal earthquake

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Geodesy and Geodynamics 2022年第5期13卷 525-533页

作者： Ram.krishna Tiwari Harihar Paudyal Daya Shanker Central Department of Physics Tribhuvan UniversityKirtipurKathmanduNepal Birendra multiple Campus Tribhuvan UniversityBharatpurChitwanNepal Department of Earthquake Engineering Indian Institute of Technology RoorkeeRoorkeeUttarakhandIndia

In the present study,the spatial-temporal distribution of b-value along the five faults area(the Judi fault,Thaple fault,Kathmandu fault,motihari-Gauri Shanker fault,and motihari-Everest fault)was investigated after the Gorkha earthquake(m7.8).The earthquake catalog of 10,500 events was prepared by compiling the published *** study area is bounded in the central Himalaya from 26.5°to 29°in latitude direction and 84°to 87°in longitude *** frequency magnitude distribution shows the variation of the b-value along with fault areas from 0.45 to 0.69,indicating a common characteristic of aftershock *** particular,the Judi fault area,Thaple fault area,and motihari-Everest fault area are characterized by the low b-values of 0.45±0.02,0.48±0.02,and 0.55±0.04,*** regions could be the source region for future *** low b-value observed for fault areas are also consistent with the thrust faulting pattern in the region as indicated by the focal mechanism of mainshock and major *** temporal variation of b-value shows inevitable fluctuations during25 April to 12 may *** the area selected,the motihari-Everest fault area is in critical strain(mechanically locked)conditions,as indicated by the stepwise energy release pattern.

关键词： Frequency-magnitude distribution Time series analysis Thrust fault Stress Central Himalaya

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