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Phenomenological modelling of flow behaviour of 20MnMoNi55 reactor pressure vessel steel at cryogenic temperature with different strain rates

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Defence Technology（防务技术） 2019年第3期15卷 326-337页

作者： Swagatam Paul Partha Dey Snehasish Bhattacharjee Sanjib kumar Acharyya prasanta Sahoo Jayanta Chattopadhyay Department of Mechanical Engineering Jadavpur University Kolkata India Department of Mechanical Engineering Academy of Technology Hooghly West Bengal India Bhaba Atomic Research Centre Mumbai India

In the present study a phenomenological constitutive model is developed to describe the flow behaviour of 20MnMoNi55 low carbon reactor pressure vessel (RPV) steel at sub-zero temperature under different strain rates. A set of uniaxial tensile tests is done with the variation of strain rates and temperature ranging from 10^-4s^-1 to 10^-1s^-1 and -80℃ to 140℃ respectively. From the experimental data, family of flow curves at different temperatures and strain rates are generated and fitted exponentially. The strain rate and temperature dependence of the coefficients of the exponential flow curves are extracted from these curves and characterised through a general phenomenological constitutive coupled equation. The coefficients of this coupled equation are optimised using genetic algorithm. Finite element simulation of tensile tests at different strain rates and temperatures are done using this coupled equation in material model of Abaqus FEA software and validated with experimental results. The novelties of proposed model are:(a) it can predict precisely the flow behaviour of tensile tests (b) it is a simple form of equation where fitting parameters are both function of strain rate ratio and temperature ratio,(c) it has ability to characterize flow behaviour with decreasing subzero temperatures and increasing strain rates.

关键词： Flow behaviour RPV steel Cryogenic temperature Strain rate

Distribution of geochemical fractions of phosphorus and its ecological risk in sediment cores of a largest brackish water lake, South Asia

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International Journal of Sediment Research 2019年第3期34卷 251-261页

作者： Saroja kumar Barik Satyanarayan Bramha Tapan kumar Bastia Dibakar Behera Pratap kumar Mohanty prasanta Rath School of Applied Sciences Department of Chemistry KIIT University Health Safety and Environment Group Indira Gandhi Centre for Atomic Research Department of Atomic Energy Government of India Department of Marine Sciences Berhampur University

The current study focuses on the vertical profile of different geochemical fractions of phosphorus-loosely bound(Lo–P), aluminium bound(Al–P), iron bound(Fe–P), calcium bound(Ca–P), and organic bound phosphorus(O–P) along with ecological risk assessment of sediment cores from Chilika Lake, eastcoast of India. The percentage contribution of the different fractions to the sedimentary phosphorus in the sediment column of the whole lake are on the order: O–P(33.2%) 4 Ca–P(20.3%) 4 Fe–P(18%) 4 Al–P(6.7%) 4 Lo–P(0.35%). The Phosphorus Pollution Index(PPI) revealed the contamination of lake sediment with phosphorus. The principal component and cluster analyses highlighted the anthropogenic contribution of phosphorus. The negative loading of Ca–P with Ca points towards its origin from marine shells. The discriminate analysis showed that the variables like Ca–P, bio-available phosphorus(BAP), and p H were able to effectively discriminate the sectors in a significant manner.

关键词： Phosphorus fractions Ecological risk Sediment core Chilika Lake

Urban road segment level of service based on bicycle users' perception under mixed traffic conditions

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Journal of Modern Transportation 2017年第2期25卷 90-105页

作者： Sambit kumar Beura Haritha Chellapilla prasanta kumar Bhuyan Department of Civil Engineering National Institute of `Technology Rourkela

During the past two decades, several methodologies are endorsed to assess the compatibility of roadways for bicycle use under homogeneous traffic conditions. However, these methodologies cannot be adopted under heterogeneous traffic where on-street bicyclists encounter a complex interaction with various types of vehicles and show divergent operational characteristics. Thus, the present study proposes an initial model suitable for urban road segments in mid-sized cities under such complex situations. For analysis purpose, various operational and physical factors along with user perception data sets （13,624 effective ratings in total） were collected from 74 road segments. Eight important road attributes affecting the bicycle service quality were identified using the most recent and most promising machine learning technique namely, random forest. The identified variables are namely, effective width of outside through lane, pavement condition index, traffic volume, traffic speed, roadside commercial activities, interruptions by unauthorized stoppages of intermittent public transits, vehicular ingress-egress to on-street parking area, and frequency of driveways carrying a high volume of traffic. Service prediction models were developed using ordered probit and ordered logit modeling structures which meet a confidence level of 95%. Prediction performances of developed models were assessed in terms of several statistical parameters and the ordered probit model outperformed the ordered logit model. Incorporating outputs of the probit model, a pre- dictive equation is presented that can identify under what level a segment is offering services for bicycle use. The service levels offered by roadways were classified into six categories varying from ＇excellent＇ to ＇worst＇（A-F）.

关键词： Heterogeneous traffic Bicyclelevel of service Perceived satisfaction Random forest Ordered probit Ordered logit

Phenol in High-mass Star-forming Regions

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Research in Astronomy and Astrophysics 2022年第6期22卷 256-268页

作者： Rana Ghosh Milan Sil Suman kumar Mondal prasanta Gorai Dipen Sahu Rahul kumar Kushwaha Bhalamurugan Sivaraman Ankan Das Indian Centre for Space Physics 43 ChalantikaGaria Station RoadKolkata 700084India S.N.Bose National Centre for Basic Sciences Salt LakeKolkata 700106India Department of Space Earth&EnvironmentChalmers University of TechnologySE-41296 GothenburgSweden Institute of Astronomy and Astrophysics Academia Sinica Taipei Taipei 10617China Atomic and Molecular Physics Laboratory Institute for Nuclear Research(Atomki)Debrecen H-4026Hungary Physical Research Laboratory NavrangpuraAhmedabad 380009India

Phenol,which belongs to the C_(6)H_(6)O isomeric group,is the simplest molecule in the family of alcohol of the aromatic *** phenol has yet to be detected in the interstellar medium,a tentative identification was reported toward the Orion KL hot core using the IRAM-30 m line *** explore some more species of this isomeric group,we consider ten species to study the fate of their astronomical *** is noticed that phenol is the most energetically favorable isomer of this *** contrast,propargyl ether is the least favorable(having relative energy~103kcal mol^(-1)compared to phenol)species of this *** far,the studies associated with the formation of phenol are heavily concentrated on combustion ***,we suggest a few key reactions(C_(6)H_(6)+OH→C_(6)H_(5)+H_(2)O,C_(6)H_(6)+O→C_(6)H_(5)OH,C_(6)H_(6)+H→C_(6)H_(5)+H_(2),and C_(6)H_(5)+OH→C_(6)H_(5)OH+hν)for the formation of *** these pathways are included in a large gas-grain chemical network to study its formation in high mass star-forming regions and dark cloud *** is noticed that the phenyl(-C_(6)H_(5))formation by the ice-phase hydrogen abstraction reaction of benzene(i.e.,C_(6)H_(6)+OH→C_(6)H_(5)+H_(2)O if allowed at~10 K)could serve as the starting point for the formation of phenol in the gas phase by radiative association reaction C_(6)H_(5)+OH→C_(6)H_(5)OH+hν.The gasphase reaction C_(6)H_(6)+O→C_(6)H_(5)OH significantly contributes to the formation of phenol,when the ice-phase reaction C_(6)H_(6)+OH→C_(6)H_(5)+H_(2)O is not considered at low *** 4 ALMA archival data of a hot molecular core,G10.47+0.03,are *** yields an upper limit on phenol abundance of 5.19×10^(-9).Our astrochemical model delivers an upper limit on phenol abundance of~2.20×10^(-9)in the hot molecular core,whereas its production in the dark cloud is not satisfactory.

关键词： astrochemistry-ISM abundances-ISM molecules-(ISM:)evolution

Morphological and molecular description of a new species of sandfly,Sergentomyia(Neophlebotomus)ashwanii ***.(Diptera:Psychodidae)from Western Ghats,India

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Asian Pacific Journal of Tropical Medicine 2024年第5期17卷 226-234页

作者： prasanta Saini Harish kumar Shah Mathew Jessu Sonia T Tom Anns KP Amju ICMR-Vector Control Research Centre(Field Station) KottayamKeralaIndia

Objective:To report a new species of sandfly,Sergentomyia(Neophlebotomus)ashwanii ***.(Diptera:Psychodidae)from Western Ghats,***:A systematic sandfly survey was conducted in the Thrissur and Kollam districts of Kerala,India using mechanical aspirators,light and sticky traps,both indoor and outdoor habitats,for a period of one *** acid barcoding of samples was performed targeting mitochondrial cytochrome oxidase I(COI)gene and sequence generated was subjected to phylogenetic ***:Sergentomyia(Neophlebotomus)ashwanii,a new sandfly species is recorded and described in this communication.A single row of 10-12 pointed teeth in the cibarium with 4-6 small denticles or fore-teeth are the key characteristics that is distinctive from other members of the subgenus *** COI barcode followed by phylogenetic analysis of the nucleotide sequence confirms that specimens of the species belong to the same taxonomic group while the genetic distance(14.2%)with the congeners established it to be a different ***:The Western Ghats'being an important biodiversity hotspot and has dearth of systematic entomological surveys on *** current study tried to fill the void and also report a new sandfly species.

关键词： Sergentomyia(Neophlebotomus)ashwanii COI barcode Western Ghats Phlebotomine sandflies

Dimensional Amplitude Response Analysis of Vibrations Produced by Defects in Rolling Contact Bearings

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Sound & Vibration 2022年第2期56卷 165-191页

作者： Imran M.Jamadar B.Suresha prasanta kumar Samal S.A.I.Bellary Department of Mechanical Engineering The National Institute of EngineeringMysuruKarnataka570008India Department of Mechanical Engineering AIKTCSchool of Engineering and TechnologyNew PanvelNavi MumbaiMaharashtra410206India

Usage of rolling contact bearings in variety of rotor-dynamic applications has put forth a need to develop a detailed and easy to implement techniques for the assessment of damage related features in these bearings so that before mechanical failure,maintenance actions can be planned well in *** accordance to this,a method based on dimensional amplitude response analysis and scaling laws is presented in this paper for the diagnosis of defects in different components of rolling contact bearings in a dimensionally scaled rotor-bearing ***,bearing,operating and defect parameters involved are detailed for dimensional analysis using frequency domain vibration data.A defect parameter for modeling all the three dimensions of the defect as well as the different shapes like square,circular,rectangular is put forth which takes into account the volume as well as the surface area of the *** data set is generated for the‘model’bearing(designated as SKF30205J2/Q)using Box-Behnken design of response surface methodology for solution of the theoretical model by factorial regression *** metamodel is then used for the prediction of the objective variable,i.e.,Vibration acceleration amplitude at the defect frequency component for other types of‘test’bearings(designated as SKF 30305C and SKF 22220 EK)using the developed scaling *** experiments showed that the computable relationship amongst objective variable and the dimensionless parameters can be forecast and correlated.

关键词： Dimensional-amplitude-response scaling laws metamodels rotor-bearing system

Performance-based intersection layout under a flyover for heterogeneous traffic

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Journal of Modern Transportation 2015年第2期23卷 119-129页

作者： Avijit Maji Akhilesh kumar Maurya Suresh Nama prasanta K.Sahu Indian Institute of Technology Bombay Indian Institute of Technology Guwahati Post Doctoral Fellow University of Regina

Flyovers are constructed to manage heavy through movement. However, traffic operations underneath a flyover remain unmanaged and often pose a major con- cern in developing countries with non-lane-based hetero- geneous traffic. This may reduce the overall benefit of a flyover. An alternative intersection layout is proposed to improve traffic operations at the intersection underneath a flyover. The proposed layout segregates the traffic move- ments through effective channelization. A traffic island is also proposed in the middle of the intersection to facilitate concurrent right-turning movements. This layout helps in eliminating a signal phase and cuts down traffic cycle time by 40 %. A microsimulation-based traffic simulation model is developed for the evaluation of the proposed layout. The simulation model demonstrates effectiveness of the proposed layout. Average delay and average queue length are compared to measure the effectiveness. Traffic volume sensitivity analysis is conducted to estimate the capacity of the proposed layout. An intersection underneath a flyover along the Eastern Expressway in Mumbai is considered for the case study. The effectiveness of the proposed layout at the study location for varying flow level is evaluated by comparing average delay, average stop delay, average number of stops per vehicle, average queue length, and maximum queue length.

关键词： Intersection layout Channelization Trafficoperational performance Flyover intersection Heterogeneous traffic

Synthesis of Fluorite-Type Nanopowders by Citrate-Nitrate Auto-Combustion Process: A Systematic Approach

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Materials Sciences and Applications 2012年第2期3卷 110-115页

作者： Mridula biswas prasanta kumar Ojha Chadalapaka Durga Prasad Nitin Madhusudan Gokhale Suresh Chandra Sharma 不详

Citrate-nitrate autocombustion process is a promising synthesis route in the field of nanomaterials. This route involves many controlling parameters which ultimately affect properties of the products. In the present research work, the effect of concentration of fuel to that of metal nitrates has been studied in a systematic manner. The nature of exothermic reaction was analyzed with DSC-TGA and the powder properties were characterized by XRD, TEM and BET measurement. The properties of the powders have been explained with respect to fuel content, vigorousness of the exothermic reaction, combustion temperature and duration. The most vigorous reaction was found to occur for the composition with FER of 0.50 with the production of the smallest crystallite size of 9 nm.

关键词： Combustion Synthesis DSC-TGA XRD TEM

Holocene Biostratigraphic Zones Corresponding Litho-Chronostratigraphy, Environment of Deposition and Successive Changes in the Geomorphology of Bengal Basin, India during Last 10,000 Years

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International Journal of Geosciences 2016年第4期7卷 615-629页

作者： prasanta kumar Sen Manju Banerjee Department of Botany Bankim Sardar College South 24 Parganas West Bengal India Department of Botany University of Calcutta Kolkata India

Biostratigraphic Zones Bb. Bz. H. I-V distinguished in C14 dated Peat, peaty clay sediments above arid, Barren zone have identified distinct environment of deposition as fresh water mixed brackish water to shallow marine to brackish water mangrove swamp, brackish water mixed fresh water swamp followed by colonization of non-littoral species to fresh water swamp during Holocene in the Bengal basin, India in chronological succession. The successive phases of depositional environment have identified the events of sea level rise, marine transgression and sea ward movement of the sea. The unique database has explored successive changes in the geomorphology of South Bengal from upland dry to marine deltaic environment to fresh water upland condition.

关键词： Holocene Biostratigraphy Flandrian Transgression Geomorphology Bengal Basin