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Investigation of two coronal mass ejections from circular ribbon source region:Origin,Sun-Earth propagation and Geoeffectiveness

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Research in Astronomy and Astrophysics 2021年第12期21卷 531-549页

作者： m.Syed Ibrahim Wahab Uddin Bhuwan Joshi Ramesh chandra Arun Kumar Awasthi aryabhatta research institute of observational sciences nainital 263002 india kodaikanal solar observatory indian institute of astrophysicskodaikanal-624103tamil naduindia udaipur solar observatory physical research laboratoryudaipur 313004india department of physics dsb campuskumaun universitynainital 263002india cas key laboratory of geospace environment department of geophysics and planetary sciencesuniversity of science and technology of chinahefei 230026china

In this article,we compare the properties of two coronal mass ejections(CmEs)that show similar source region characteristics but different evolutionary behaviors in the later *** discuss the two events in terms of their near-Sun characteristics,interplanetary evolution and *** carefully analyzed the initiation and propagation parameters of these events to establish the precise CmEinterplanetary CmE(ICmE)connection and their near-Earth *** first event is associated with poor geomagnetic storm disturbance index(Dst≈-20 n T)while the second event is associated with an intense geomagnetic storm of DST≈-119 n *** configuration of the sunspots in the active regions and their evolution are observed by Helioseismic and magnetic Imager(HmI).For source region imaging,we rely on data obtained from Atmospheric Imaging Assembly(AIA)on board Solar Dynamics Observatory(SDO)and Hαfiltergrams from the Solar Tower Telescope at Aryabhatta Research Institute of Observational Sciences(ARIES).For both the CmEs,flux rope eruptions from the source region triggered flares of similar intensities(≈m1).At the solar source region of the eruptions,we observed a circular ribbon flare(CRF)for both cases,suggesting fan-spine magnetic configuration in the active region *** multi-channel SDO observations confirm that the eruptive flares and subsequent CmEs were intimately related to the filament *** the Large Angle and Spectrometric Coronograph(LASCO)field of view(FOV)the two CmEs propagated with linear speeds of 671 and 631 km s-1,*** CmEs were tracked up to the Earth by Solar Terrestrial Relations Observatory(STEREO)*** find that the source region evolution of CmEs,guided by the large-scale coronal magnetic field configuration,along with near-Sun propagation characteristics,such as CmE-CmE interactions,played important roles in deciding the evolution of CmEs in the interplanetary medium and subsequently their geoeffec

关键词： Sun:coronal mass ejections(CmEs) Sun:flares

High-pressure investigations on Piplia Kalan eucrite meteorite using in-situ X-ray diffraction and ^(57)Fe mssbauer spectroscopic technique up to 16 GPa

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Geoscience Frontiers 2016年第2期7卷 265-271页

作者： Usha chandra K.K. Pandey G. Parthasarathy Surinder m. Sharma Department of Physics University of Rajasthan Jaipur 302 004 India High Pressure & Synchrotron Radiation Physics Division Bhabha Atomic Research Centre Trombay Mumbai 400 085 India CSIR-National Geophysical Research Institute Uppal Road Hyderabad 500 007 India

We report here high-pressure investigations on Piplia Kalan eucrite-a member of HED （Howardite -Eucrite-Diogenite） family from asteroid 4-Vesta based on synchrotron X-ray diffraction （up to 16 GPa） and ^57Fe mossbauer spectroscopy （up to 8 GPa）. Dominant with anorthite-rich plagioclase, pigeonite-rich pyroxene and clino-ferrosilite, the sample displayed various phase transitions attaining amorphous character at 16 GPa. These phase transitions of individual components could be explained simultaneously through variations in high-pressure XRD patterns and the mossbauer parameters. most prominent P21/c to C2/c transition of pigeonite and ferrosilite was exhibited both as sudden variation in mossbauer parameters and population inversion of Fe^2＋ in m1 and m2 sites between 2.9 and 3.8 GPa and variation in intensity profile in XRD patterns at 3.56 GPa. Anorthite seemed to respond more to such impact than other components in the sample. Complete amorphization in anorthite which occurred at lower pressure of - 12 GPa implied residual stress experienced due to shock impact. The presence of high pressure （monoclinic） phase of pigeonite and ferrosilite at ambient condition in this eucrite sample confirmed earlier suggestions of an early shock event. This report is an attempt to emphasize the role of anorthite in the determination of the residual stress due to impact process in the parent body thus to understand the behavioral differences amongst HED members.

关键词： meteorites High pressure X-ray diffraction mossbauer spectroscopy Eucrites synchrotron radiation Ferrosilite

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

Predicting the Potential Invasion Hotspots of Chromolaena odorata under Current and Future Climate Change Scenarios in Heterogeneous Ecological Landscapes of mizoram,India

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Research in Ecology 2023年第3期5卷 19-30页

作者： Rabishankar Sengupta Sudhansu sekhar Dash Central National Herbarium Botanical Survey of IndiaHowrah711103India Botanical Survey of India CGO ComplexDF BlockSector-1Kolkata700019India

Recent trends in globalization,human mobility surge and global trade aggravated the expansion of alien species introduction leading to invasion by alien plants compounded by climate *** ability to predict the spread of invasive species within the context of climate change holds significance for accurately identifying vulnerable regions and formulating strategies to contain their wide proliferation and *** activities and recent climate change scenarios increased the risk of Chromolaena odorata invasion and habitat expansion in *** forecast its current distribution and habitat suitability amidst climatic alterations in mizoram,a maxEnt-driven habitat suitability model was deployed using the default *** resultant model exhibited that the current spatial range of *** occupies 15.37%of geographical areas deemed suitable for varying degrees of *** for 2050 and 2070 anticipated an expansion of suitable habitats up to 34.37%of the geographical area of mizoram,specifically under RCP 2.6 in 2070 in comparison with its present ***,the distributional range of *** in mizoram spans from lower(450 m)to mid elevational ranges up to 1700 meters,with limited presence at higher ***,the habitat suitability model extrapolates that climate changes will elevate the invasion risk posed by *** across mizoram,particularly in the North-Western and Central *** projection of further territorial expansion and an upward shift in altitudinal range in the future underscores the urgency of instating robust management measures to pre-empt the impact of *** *** study recommends the imperative nature of effective *** management,particularly during the initial stages of invasion.

关键词： Climate change Niche modelling Habitat suitability Biodiversity hotspots Plant invasion maxent

P systems with array objects and array rewriting rules

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Progress in Natural Science:materials International 2007年第4期17卷 479-485页

作者： K.G. Subramanian R. Saravanan m. Geethalakshmi P. Helen chandra m. margenstern Department of Computer Science Sri Muthukumaran Institute of TechnologyChennai 600 069India Department of mathematics Bharath Institute of Higher Education and ResearchChennai 600 073India Department of mathematics Dr. MGR Janaki CollegeAdayarChennaiIndia Department of mathematics Jayaraj Annapackiam College for Women Periyakulam 625 601India LITA Universite Paul Verlaine-MetzIle du Saulcy57045 Metz CedexFrance

Array P systems were introduced by Paun Gh. which is linking the two areas of membrane computing and picture grammars. Puzzle grammars were introduced by us for generating connected picture arrays in the two-dimensional plane, motivated by the problem of tiling the plane. On the other hand, incorporating into arrays the developmental type of generation used in the well-known biologically motivated L systems, Siromoney and Siromoney proposed a very general rectangular array generating model, called extended controlled tabled L array system (ECTLAS). In this paper we introduce two variations of the array P system, called BPG array P system and parallel array P system. The former has in the regions array objects and basic puzzle grammar rules (BPG), which are a specific kind of puzzle grammar rules. In the latter, the regions have rectangular array objects and tables of context-free rules. We examine these two types of P systems for their array generative power.

关键词： membrane computing P systems array grammars.

Stable Fano-like plasmonic resonance: its impact on the reversal of far-and near-field optical binding force

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Communications in Theoretical Physics 2020年第4期72卷 89-105页

作者： Hamim mahmud Rivy m R C mahdy Nabila masud Ziaur Rahman Jony Saikat chandra Das Department of Electrical&Computer Engineering North South UniversityBashundharaDhaka1229Bangladesh School of Electrical and Electronic Engineering Nanyang Technological University50 Nanyang Ave639798 Singapore Pi Labs Bangladesh LTD ARA Bhaban39Kazi Nazrul Islam AvenueKawran BazarDhaka 1215Bangladesh

Even for a 100 nm interparticle distance or a small change in particle shape,optical Fano-like plasmonic resonance mode usually vanishes *** would be remarkable if stable Fano-like resonance could somehow be achieved in distinctly shaped nanoparticles for more than 1μm interparticle distance,which corresponds to the far electromagnetic field *** such far-field Fano-like plasmonic resonance can be achieved,controlling the reversal of the far-field binding force can be attained,like the currently reported reversals for near-field *** this work,we have proposed an optical set-up to achieve such a robust and stable Fano-like plasmonic resonance,and comparatively studied its remarkable impact on controlling the reversal of near-and far-field optical binding *** our proposed set-up,the distinctly shaped plasmonic tetramers are half immersed(***-benzene)in an inhomogeneous dielectric interface and illuminated by?circular?polarized *** have demonstrated significant differences between near-and far-field optical binding forces along with the Lorentz force field,which partially depends on the object’s shape.A clear connection is shown between the far-field binding force and the resonant modes,along with a generic mechanism to achieve controllable Fano-like plasmonic resonance and the reversal of the optical binding force in both far-and near-field configurations.

关键词： Fano resonance optical binding force Lorentz force plasmonic tetramer

Evaluation of Radarsat-2 quad-pol SAR time-series images for monitoring groundwater irrigation

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International Journal of Digital Earth 2019年第10期12卷 1177-1197页

作者： Amit Kumar Sharma Laurence Hubert-moy Buvaneshwari Sriramulu m.sekhar Laurent Ruiz S.Bandyopadhyay Shiv mohan Samuel Corgne Univ Rennes UMR LETG CNRSRennesFrance Indo-French Cell for Water Science Indian Institute of ScienceBangaloreIndia Department of Civil Engineering Indian Institute of ScienceBangaloreIndia UmR 1069 SAS INRAAgro-campus OuestRennesFrance Géosciences Environnement Toulouse Universitéde ToulouseCNRSIRDToulouseFrance EOS Indian Space Research OrganizationBangaloreIndia PLANEX Physical Research LaboratoryAhmedabadIndia

Groundwater assists farmers to irrigate crops for fulfilling the crop-water *** agriculture system is characterized by three cropping seasons known as Kharif(monsoon),Rabi(post-monsoon)and summer(pre-monsoon).In tropical countries like India,monitoring cropping practices using optical remote sensing during Kharif and Rabi seasons is constraint due to the cloud cover,which can be well addressed by microwave remote *** the proposed research,the strength of C-band polarimetric Synthetic Aperture Radar(SAR)time series images were evaluated to classify groundwater irrigated croplands for the Kharif and Rabi cropping seasons of the year *** present study was performed in the Berambadi experimental watershed of Kabini river basin,southern peninsular India.A total of fifteen polarimetric variables were estimated includes four backscattering coefficients(HH,HV,VH,VV)and eleven polarimetric indices for all Radarsat-2 SAR *** cumulative temporal sum(seasonal and dual-season)of these parameters was supervised classified using Support Vector machine(SVm)classifier with intensive ground observation *** results using the best equation(highest accuracy and kappa)shows that the Kharif,Rabi and irrigated double croplands are respectively 9.58 km2(20.6%),16.14 km2(34.7%)and 6.22 km2(13.4%)with a kappa coefficient respectively 0.84,0.74 and 0.94.

关键词： Radarsat-2 Synthetic Aperture Radar Polarimetric Indices Irrigated Cropland Support Vector machine Classifier Kabini Critical Zone Observatory

Wind pollination in Pinus roxburghii

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Progress in Natural Science:materials International 2007年第1期17卷 32-38页

作者： Vinod Prasad KHANDURI chandra mohan SHARmA Department of Forestry mizoram University Aizawl(Mizoram)India Department of Forestry HNB Garhwal University Srinagar Garhwal-246 174(Uttaranchal)India

Stigmatic pollen load and pollen concentration in the air were studied in the natural population of Pinus roxburghii at Ashtavakra (900 m asl), in the Pauri forest division of Garhwal Himalaya, India. The results reflect diurnal pollen occurrence in P. roxburghii , with the strong significant correlations between pollen concentrations in the air and wind speed, air temperature and relative air humidity. A significant correlation was also observed between microsporangium dehiscence and pollen occurrence in the air. The maximum concentration of pollen grains in the air and higher rates of pollen deposition onto the megasporophylls were between 12 pm and 16 pm of the day, which conforms the best time for pollination in a day in P. roxburghii. The receptivity of Ovulate strobili varied from 3 to 5 days, however, the bagged strobili remained receptive up to 6 days.

关键词： ovulate strobili pollen cones pollination receptivity wind speed P. roxburghii.

Effect of Gd addition on the superconducting properties of Ti-based V, Nb, Ta alloys

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Superconductivity 2023年第2期6卷 58-63页

作者： SK Ramjan LS.Sharath chandra Rashmi Singh m.K.Chattopadhyay Free Electron Laser Utilization Laboratory Raja Ramanna Centre for Advanced TechnologyIndore 452013Madhya PradeshIndia Homi Bhabha National Institute Training School ComplexAnushakti NagarMumbai 400094MaharastraIndia Laser and Functional materials Division Raja Ramanna Centre for Advanced TechnologyIndore 452013Madhya PradeshIndia

The critical current density(Jc)of the body centered cubic(bcc)V0.6Ti0.4 alloy enhances significantly after the addition of rare earth Gd as the latter is immiscible in the matrix[***,***,IEEE ***.31,5(2021)].Very low solubility of Gd in other bcc elements like Ta and Nb is also well known[*** Gschneidner in Prog Sci Technol Rare Earths,vol.1,pp.222–258,1964&m Neuberger,*** in Handbook of Electronic materials,Vol 4,1972].We use these facts to find the effect of adding 1 at.%Gd into the Nb0.6Ti0.4 and Ta0.4Ti0.6 alloys on the superconducting properties e.g.,the transition temperature(Tc),Jc,flux pinning force density(Fp)and the *** spite of Gd being ferromagnetic,the Tc in these alloys change only marginally(increase by 0.3 K in Ta0.4Ti0.6 and decrease by 0.15 K in Nb0.6Ti0.4 after Gd *** Jc(H?1 T,T=4 K)increases by 5 and 1.5 times respectively in the Gd containing Nb0.6Ti0.4 and Ta0.4Ti0.6 alloys,which is quite small as compared to the increase observed in the V0.6Ti0.4(20 times)*** Gd addition,the grain size reduces approximately by 65%and 10%respectively in Nb0.6Ti0.4 and *** analysis indicates that grain boundaries are the major flux line pinning centres in these alloys and the role of Gd in increasing the Jc depends on the effectiveness of Gd in reducing the grain *** grain boundary density depends strongly on the distribution of Gd precipitates,which is quite different from each other for two alloy systems under ***,our results suggest that the addition of Gd to commercial Nb‐Ti(Nb0.37Ti0.63)alloy is a new promising route for achieving higher Jc values.

关键词： Critical current density Ferromagnetism Flux pinning Grain boundary