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Journal of Materiomics 2022年第3期8卷 669-677页

作者： Rahul Singh Shiv Kumar A.Jain Mahima Singh Labanya Ghosh A.Singh Soma Banik A.Lakhani S.Patil E.F.Schwier K.Shimada S.M.Yusuf sandip chatterjee Solid State Physics Division Bhabha Atomic Research CenterTrombayMumbai400085India Hiroshima Synchrotron Radiation Center HiroshimaJapan Homi Bhabha National Institute AnushaktinagarMumbai400094India Department of Physics Indian Institute of Technology(BHU)Varanasi221005India Synchrotrons Utilization Section Raja Ramanna Centre for Advanced TechnologyIndore452013India UGC-DAE Consortium for Scientific Research IndoreMadhya Pradesh452017India Department of CMP&MS Tata Institute of Fundamental ResearchMumbai400005India

The topological insulators Bi_(2-x)Fe_(x)Se_(3-x)S_(x) have been investigated by the dc-magnetization,magnetotransport and angle resolved photoemission spectroscopy(ARPES)*** doping of Fe and S,a negative giant magneto-resistance(MR)is observed for parallel electric and magnetic fields(H||E).The MR behavior at lower magnetic field can be explained with the semi-classical theory whereas the MR behavior at higher field has been attributed to the axial ***,the system reached to the quantum limit at low magnetic field(~4.5T).The magnetic ordering can be explained with the presence of both the RKKY(surface)and van-Vleck(bulk)*** ARPES study reveals that a surface gap is suppressed when the magnetic ordering changes from ferromagnetic to anti-ferromagnetic *** ARPES study and the appearance of quantum oscillations(SdH)in the resistivity pattern reveal that the topological surface property is preserved with the co-doping of Fe and S.

关键词： Spintronics Magnetoresistance Magnetism Topological insulators RKKY interaction ARPES study

Accretion flow properties of XTE J1118+480 during its 2005 outburst

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Research in Astronomy and Astrophysics 2020年第11期20卷 222-230页

作者： Dipak Debnath Debjit chatterjee Arghajit Jana sandip K.Chakrabarti Kaushik chatterjee Indian Centre for Space Physics 43 ChalantikaGaria St.Rd.Kolkata700084India Physical Research Laboratory NavrangpuraAhmedabad 380009India

We study spectral and temporal properties of Galactic short orbital period transient black hole XTE J1118+480 during its 2005 outburst using archival data of RXTE PCA and HEXTE instruments in the combined energy range of 3−100 *** analysis with the physical two component advective flow(TCAF)model allows us to understand the accretion flow properties of the *** found that this outburst of XTE J1118+480 is an unconventional outburst as the source was only in the hard state(HS).Our spectral analysis suggests that during the entire outburst,the source was highly dominated by the low angular momentum sub-Keplerian halo *** the source was active in radio throughout the outburst,we make an effort to estimate X-ray contribution of jets to total observed X-ray emissions from the spectral analysis with the TCAF *** total X-ray intensity shows a similar nature of evolution as that of radio and jet X-ray *** allowed us to define this‘outburst’also as a jet dominated‘outburst’.Total X-ray flux is also found to subside when jet activity *** detailed spectral analysis also indicated that although the source was only in the HS during the outburst,in the late declining phase the spectrum became slightly softer due to the slow rise in the Keplerian disk rate.

关键词： X-Rays binaries-stars black holes-stars individual (XTE J1118+480)-accretion,accretion disks-ISM jets and outflows-radiation dynamics

Inference on disk-jet connection of MAXI J1836–194 from spectral analysis with the TCAF solution

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Research in Astronomy and Astrophysics 2020年第3期20卷 28-41页

作者： Arghajit Jana Dipak Debnath sandip KChakrabarti Debjit chatterjee Indian Centre for Space Physics 43 ChalantikaGaria St.Rd.Kolkata700084India

Galactic transient black hole candidate(BHC)MAXI J1836–194 was discovered on 2011 Aug30,by MAXI/GSC and Swift/*** source activity during this outburst continued for^3 months before entering into the quiescent *** again became active in March 2012 and continued for another^2 *** this paper,3-25 keV RXTE/PCA spectra from the 2011 outburst and 0.5-10.0 keV Swift/XRT data during its 2012 outburst are analyzed with the two-component advective flow(TCAF)model based fits files in *** calculate the X-ray contributions coming from jets/outflow using a newly developed method based on the deviation of the TCAF model *** also study the correlation between observed radio and estimated jet X-ray *** correlation indices(b)are found to be 1.79 and 0.61,when the 7.45 GHz Very Large Array(VLA)radio flux is correlated with the total X-ray and jet X-ray fluxes in 3-25 keV range *** has been found that the jet contributes in X-rays up to a maximum of 86%during its 2011 *** makes the BHC MAXI J1836–194 strongly jet dominated during the initial rising phase.

关键词： X-Rays:binaries stars individual:(MAXI J1836–194) stars:black holes accretion,accretion disks ISM:jets and outflows radiation:dynamics

Application of Cole-Cole model to transformer oil-paper insulation considering distributed dielectric relaxation

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High Voltage 2019年第1期4卷 72-79页

作者： sandip Kumar Ojha Prithwiraj Purkait Biswendu chatterjee Sivaji Chakravorti Department of Electrical Engineering Haldia Institute of TechnologyHaldia721657West BengalIndia Department of Electrical Engineering St.Thomas'College of Engineering&TechnologyKolkata700023West BengalIndia Electrical Engineering Department Jadavpur UniversityKolkata700032West BengalIndia Electrical Engineering Department Currently at NIT Calicut on lien from Jadavpur UniversityKolkata700032West BengalIndia

Researchers have been exploring dielectric testing techniques both in time and frequency domain for insulation condition assessment of oil-paper insulated *** a practical dielectric system,dipoles are found to behave according to a distribution of elementary Debye relaxation *** distribution density functions have been proposed to characterise such many-body interaction ***-Cole diagrams can be one of the methods for studying the nature of frequency dependency of dielectric materials of complex ***-Cole plots are commonly used for characterising different materials such as dielectric mixtures,ionic liquids,cable insulating oil,polar liquids *** scope of its application for assessing transformer oil-paper insulation considering distributed relaxation process has not been explored *** present contribution discusses mathematical formulations used for transforming the experimentally obtained time domain dielectric response test data to distribution domain and further to frequency domain for obtaining the Cole-Cole *** about the influence of various operating conditions and insulation status on the Cole-Cole diagram have been reported in this *** of tests on field transformers are also *** paper attempts to employ the features of Cole-Cole diagrams as potential indicators for analysing condition of the oil-paper insulation considering distributed relaxation process.

关键词： properties structure process

Folic acid protects against fluoride-induced oxidative stress and testicular damage in rats

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Asian pacific Journal of Reproduction 2021年第6期10卷 274-283页

作者： Ray Dibyendu chatterjee Tiasa Monalisha Das Panda Pradip Mukherjee sandip Department of Physiology Serampore CollegeSeramporeHooghly-712201West BengalIndia Department of Statistics Serampore CollegeSeramporeHooghly-712201West BengalIndia

Objective:To investigate the effects of folic acid on testicular oxidative damage in sodium fluoride-induced male Wistar ***:A total of 24 male Wistar rats were divided into 4 groups:the control,sodium fluoride(fed with 100 mg/L sodium fluoride through drinking water orally for 21 days),folic acid(36μg/kg body weight/day,orally),and sodium fluoride plus folic acid(received similar dose orally)*** the end of 21 days,epididymal sperm parameters,biochemical analysis of testicular tissue,and serum hormonal levels were performed along with histopathological ***:Sodium fluoride intoxication resulted in marked reduction in gonado somatic index,serum luteinizing hormone,and testosterone level along with 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase *** addition,reduction in sperm density,as well as loss of sperm motility and sperm viability,were also ***,increased levels of testicular malondialdehyde,nitrite,interleukin-6 and tumor necrosis factor-α as well as decreased levels of superoxide dismutase and catalase activities and reduced glutathione content were found to be associated with this *** acid co-treatment,on the other hand,could prevent all the sodium fluoride-induced testicular pathophysiology and oxidative stress related *** examinations of testicular sections from the experimental rats supported these ***:Combining all,this study suggests that being an antioxidant,folic acid plays a beneficial role against fluoride-induced adverse effects on the male reproductive system.

关键词： Sodium fluoride Folic acid Testicular damage Sperm Oxidative stress Antioxidants

Accretion properties of MAXI J1813-095 during its failed outburst in 2018

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Research in Astronomy and Astrophysics 2021年第5期21卷 235-246页

作者： Arghajit Jana Gaurava K.Jaisawal Sachindra Naik Neeraj Kumari Debjit chatterjee Kaushikchatterjee Riya Bhowmick sandip KChakrabarti Hsiang-Kuang Chang Dipak Debnath Astronomy&Astrophysics Division Physical Research LaboratoryNavrangpuraAhmedabad 380009India National Space Institute Technical University of DenmarkElektrovej327-328DK-2800 LyngbyDenmark High Energy Astrophysics Indian Centre for Space PhysicsGaria St RoadKolkata 700084India Department of Physics Indian Institute of TechnologyGandhinagar 382355GujaratIndia Indian Institute of Astrophysics KoramangalaBangalore 560034India Department of Physics “National Tsing Hua University”Hsinchu 30013China

We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI J1813-095 using Swift,NICER,and NuSTAR observations during its 2018 *** timing behavior of the source is mainly studied by examining NICER light curves in the 0.5−10 keV *** did not find any signature of quasi-periodic oscillations in the power density spectra of the *** carry out spectral analysis with a combined disk blackbody&power law model,and physical two-component advective flow(TCAF)*** the combined disk blackbody&power-law model,we extracted thermal and non-thermal fluxes,photon index and inner disk *** also find evidence for weak reflection in the *** have tested the physical TCAF model on a broadband spectrum from NuSTAR and Swift/*** parameters like mass accretion rates,the size of Compton clouds and the shock strength are *** result affirms that the source remained in the hard state during the entire outburst which indicates a‘failed’*** estimate the mass of the black hole as 7.4±1.5M⊙from the spectral study with the TCAF *** apply the LAOR model for the Fe K line *** this,the spin parameter of the black hole is ascertained as a^(∗)>*** inclination angle of the system is estimated to be in the range of 28°−45°from the reflection *** find the source distance to be∼6 kpc.

关键词： X-Rays:binaries stars individual:(MAXI J1813-095) stars:black holes accretion,accretion disks–shock waves radiation:dynamics

Dark Energy Accretion onto Van der Waal's Black Hole

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Communications in Theoretical Physics 2019年第2期71卷 209-219页

作者： sandip Dutta Ritabrata Biswas Department of Mathematics The University of BurdwanGolapbag Academic ComplexBurdwan-713104Purba Bard-dhamanWest BengalIndia

We consider the most general static spherically symmetric black hole metric. The accretion of the fluid flow around the Van der Waal's black hole is investigated and we calculate the fluid's four-velocity, the critical point and the speed of sound during the accretion process. We also analyze the nature of the universe's density and the mass of the black hole during accretion of the fluid flow. The density of the fluid flow is also taken into account. We observe that the mass is related to redshift. We compare the accreting power of the Van der Waal's black hole with Schwarzschild black hole for different accreting fluid.

关键词： black hole physics thermodynamics accretion disc extended Chaplygin gas

Unified Smith Predictor Based H_∞ Wide-Area Damping Controller to Improve the Control Resiliency to Communication Failure

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IEEE/CAA Journal of Automatica Sinica 2020年第2期7卷 584-596页

作者： Mithu Sarkar Bidyadhar Subudhi sandip Ghosh G H Raisoni College of Engineering Nagpur 440016India Indian Institute of Technology Goa-403401India Indian Institute of Technology Banaras Hindu University(BHU)Varanasi 221005India

Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie *** of wide-area signal is more effective than the local area signal in damping out the inter-area *** area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote *** failure is one of the disastrous phenomena in a communication *** this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area *** proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is *** time delay is an unwanted phenomenon that degrades the performance of the *** unified Smith predictor approach is used to design a Hm controller to handle the time ***'s two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed *** the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.

关键词： Communication failure dual input single output(DISO)controller H_∞control inter-area oscillation unified Smith predictor

Effect of Graphene Nanoplate and Silicon Carbide Nanoparticle Reinforcement on Mechanical and Tribological Properties of Spark Plasma Sintered Magnesium Matrix Composites

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Journal of Materials Science & Technology 2014年第11期30卷 1059-1070页

作者： Aniruddha Das sandip P.Harimkar School of Mechanical and Aerospace Engineering Oklahoma State UniversityStillwaterOK 74078USA

Processing of magnesium （Mg） matrix composites reinforced with low reinforcement content （up to 4-5 vol.%） of graphene nanoplates （GNPs） and silicon carbide （SIC） nanoparticles using bait milling and spark plasma sintering （SPS） is reported. Near full densification was observed for all the composite compositions at the sintering temperature of 450 ~C （soaking time of 5 min and applied pressure of 50 MPa）. Detailed analysis of the microstructure and mechanical and tribological （under dry sliding contact with alumina counter-face） properties with reinforcement content in Mg-GNP and Mg-SiC is presented. Mg-GNP and Mg-SiC composites reinforced with about 2 vol.% of reinforcement content exhibited significant improvement in microhardness and wear resistance as compared with Mg compacts.

关键词： Microstructure and properties Wear Tribology Magnesium matrix composites