We present observations of the active M-dwarf binary AT Mic(dM4.5e+dM4.5e)obtained with the orbital observatory Astro Sat.During 20 ks of observations,in the far-ultraviolet(130-180 nm)and soft X-ray(0.3-7 keV)spectra...We present observations of the active M-dwarf binary AT Mic(dM4.5e+dM4.5e)obtained with the orbital observatory Astro Sat.During 20 ks of observations,in the far-ultraviolet(130-180 nm)and soft X-ray(0.3-7 keV)spectral ranges,we detected both quiescent emission and at least five flares on different components of the binary.The X-ray flares were typically longer than and delayed(by 5-6 minutes)with respect to their ultraviolet counterparts,in agreement with the Neupert effect.Using X-ray spectral fits,we estimated the parameters of the emitting plasma.The results indicate the presence of a hot multi-thermal corona with average temperatures in the range of~7-15 MK and emission measure of~(2.9-4.5)×10^(52)cm^(-3);both the temperature and the emission measure increased during the flares.The estimated abundance of heavy elements in the corona of AT Mic is considerably lower than at the Sun(~0.18-0.34 of the solar photospheric value);the coronal abundance increased during the flares due to chromospheric evaporation.The detected flares had the energies of~10^(31)-10^(32)erg;the energy-duration relations indicate the presence of magnetic fields stronger than in typical solar flares.展开更多
The escalation of zeta potential by the influence of wall slip for the electrokinetically modulated flow through a microchannel motivates to consider the impact of hydrodynamic slippage upon the zeta or surface potent...The escalation of zeta potential by the influence of wall slip for the electrokinetically modulated flow through a microchannel motivates to consider the impact of hydrodynamic slippage upon the zeta or surface potential.The reported study undergoes an analytical exploration of the pulsatile electroosmosis and shear-actuated flow characteristics of a fluid with a Newtonian model through a microchannel with parallel plates by invoking the reliance of a zeta or surface potential on slippage.The linearized Poisson-Boltzmann and momentum equations are solved analytically to obtain the explicit expression of the electrical potential induced in the electrical double layer(EDL),the flow velocity field,and the volumetric flow rate for an extensive span of parameters.The velocity field proximal to the microchannel wall is observed to enhance by an apparent zeta potential,and is further escalated for a thinner EDL and an oscillating electric field with a higher amplitude.However,near the core region of the microchannel,the flow velocity becomes invariant with the EDL thickness.The result shows that the lower wall velocity contributes to the flow velocity along with the electroosmotic body force and the impact of the velocity of the wall underneath diminishes proximal to the upper wall.Moreover,the volumetric flow rate increases when the thickness of the EDL decreases,owing to the influence of the wall slip.However,for thinner EDLs and medium and higher oscillating Reynolds numbers,the volumetric flow rate varies non-monotonously,correlative to the slip-free and slip cases.展开更多
This review addresses the diverse applications of multiphase flows,focusing on drilling,completions,and injection activities in the oil and gas industry.Identifying contemporary challenges and suggesting future resear...This review addresses the diverse applications of multiphase flows,focusing on drilling,completions,and injection activities in the oil and gas industry.Identifying contemporary challenges and suggesting future research directions,it comprehensively reviews evolving applications in these multidisciplinary topics.In drilling,challenges such as gas kicks,cutting transport,and hole cleaning are explored.The application of immersion cooling technology in surface facilities for gas fields utilized in integrated bitcoin mining is also discussed.Nanotechnology,particularly the use of nanoparticles and nanofluids,shows promise in mitigating particulate flow issues and controlling macroscopic fluid behavior.Nanofluids find applications in drilling for formation strengthening and mitigating formation damage in completions as highlighted in this work,as well as in subsurface injection for enhanced oil recovery(EOR),waterflooding,reservoir mapping,and sequestration tracking.The review emphasizes the need for techno-economic analyses using multiphase flow models,particularly in scenarios involving fluid injection for energy storage.Addressing these multiphase flow challenges is crucial for the future of energy diversity and transition initiatives,offering benefits such as financial stability,resilience,sustainability,and reliable supply chains.The first part of this review presents the application of multiphase(typical gas,liquid,solid)flow models and technology for drilling,completion,and injection operations.While the second part reviews the applications of multiphase particulate(nanofluid)flow technology,the use of computational fluid dynamics(CFD),machine learning(ML),and system modeling for multiphase flow models in drilling,completions,and injection operations.展开更多
This review addresses the diverse applications of multiphase flows,focusing on drilling,completions,and injection activities in the oil and gas industry.Identifying contemporary challenges and suggesting future resear...This review addresses the diverse applications of multiphase flows,focusing on drilling,completions,and injection activities in the oil and gas industry.Identifying contemporary challenges and suggesting future research directions,it comprehensively reviews evolving applications in these multidisciplinary topics.In drilling,challenges such as gas kicks,cutting transport,and hole cleaning are explored.The application of immersion cooling technology in surface facilities for gas fields utilized in integrated bitcoin mining is also discussed.Nanotechnology,particularly the use of nanoparticles and nanofluids,shows promise in mitigating particulate flow issues and controlling macroscopic fluid behavior.Nanofluids find applications in drilling for formation strengthening and mitigating formation damage in completions as highlighted in this work,as well as in subsurface injection for enhanced oil recovery(EOR),waterflooding,reservoir mapping,and sequestration tracking.The review emphasizes the need for techno-economic analyses using multiphase flow models,particularly in scenarios involving fluid injection for energy storage.Addressing these multiphase flow challenges is crucial for the future of energy diversity and transition initiatives,offering benefits such as financial stability,resilience,sustainability,and reliable supply chains.In the first part of this review,we presented the application of multiphase(typical gas,liquid,solid)flow models and technology for drilling,completion,and injection operations.This second part of this review presents the applications of multiphase particulate(nanofluid)flow technology for drilling,completion,and injection operations.It aims to identify technology development needs related to multiphase flows,enhancing research endeavors for better cognition and mitigation of the identified issues.The use of computational fluid dynamics(CFD),machine learning(ML),and system modeling for multiphase flow models is also discussed.展开更多
We investigate the rare baryonic Λ_b→Λl^＋l^- decays in a non-universal Z＇ model, which is one of the wellmotivated extensions of the standard model（SM）. Considering the effects of Z-mediated flavour-changing ne...We investigate the rare baryonic Λ_b→Λl^＋l^- decays in a non-universal Z＇ model, which is one of the wellmotivated extensions of the standard model（SM）. Considering the effects of Z-mediated flavour-changing neutral currents（FCNCs） we analyse the differential decay rate, forward-backward asymmetries and lepton polarisation asymmetries for the Λb→Λl^＋l^- decays. We find significant deviations from their SM predictions, which could indicate new physics arising from the Z gauge boson.展开更多
基金supported by the BRICS Multilateral Research and Development Projects-2016(DST/MRCK/BRICS/Pilot Call1/Superflares/2017)the project“Superflares on stars and the Sun,”the Russian Foundation for Basic Research under Grant 17-52-80064+1 种基金the Ministry of Science and Higher Education of the Russian Federationsupported by the Research Council of Norway through its Centres of Excellence scheme(project No.262622)。
文摘We present observations of the active M-dwarf binary AT Mic(dM4.5e+dM4.5e)obtained with the orbital observatory Astro Sat.During 20 ks of observations,in the far-ultraviolet(130-180 nm)and soft X-ray(0.3-7 keV)spectral ranges,we detected both quiescent emission and at least five flares on different components of the binary.The X-ray flares were typically longer than and delayed(by 5-6 minutes)with respect to their ultraviolet counterparts,in agreement with the Neupert effect.Using X-ray spectral fits,we estimated the parameters of the emitting plasma.The results indicate the presence of a hot multi-thermal corona with average temperatures in the range of~7-15 MK and emission measure of~(2.9-4.5)×10^(52)cm^(-3);both the temperature and the emission measure increased during the flares.The estimated abundance of heavy elements in the corona of AT Mic is considerably lower than at the Sun(~0.18-0.34 of the solar photospheric value);the coronal abundance increased during the flares due to chromospheric evaporation.The detected flares had the energies of~10^(31)-10^(32)erg;the energy-duration relations indicate the presence of magnetic fields stronger than in typical solar flares.
文摘The escalation of zeta potential by the influence of wall slip for the electrokinetically modulated flow through a microchannel motivates to consider the impact of hydrodynamic slippage upon the zeta or surface potential.The reported study undergoes an analytical exploration of the pulsatile electroosmosis and shear-actuated flow characteristics of a fluid with a Newtonian model through a microchannel with parallel plates by invoking the reliance of a zeta or surface potential on slippage.The linearized Poisson-Boltzmann and momentum equations are solved analytically to obtain the explicit expression of the electrical potential induced in the electrical double layer(EDL),the flow velocity field,and the volumetric flow rate for an extensive span of parameters.The velocity field proximal to the microchannel wall is observed to enhance by an apparent zeta potential,and is further escalated for a thinner EDL and an oscillating electric field with a higher amplitude.However,near the core region of the microchannel,the flow velocity becomes invariant with the EDL thickness.The result shows that the lower wall velocity contributes to the flow velocity along with the electroosmotic body force and the impact of the velocity of the wall underneath diminishes proximal to the upper wall.Moreover,the volumetric flow rate increases when the thickness of the EDL decreases,owing to the influence of the wall slip.However,for thinner EDLs and medium and higher oscillating Reynolds numbers,the volumetric flow rate varies non-monotonously,correlative to the slip-free and slip cases.
文摘This review addresses the diverse applications of multiphase flows,focusing on drilling,completions,and injection activities in the oil and gas industry.Identifying contemporary challenges and suggesting future research directions,it comprehensively reviews evolving applications in these multidisciplinary topics.In drilling,challenges such as gas kicks,cutting transport,and hole cleaning are explored.The application of immersion cooling technology in surface facilities for gas fields utilized in integrated bitcoin mining is also discussed.Nanotechnology,particularly the use of nanoparticles and nanofluids,shows promise in mitigating particulate flow issues and controlling macroscopic fluid behavior.Nanofluids find applications in drilling for formation strengthening and mitigating formation damage in completions as highlighted in this work,as well as in subsurface injection for enhanced oil recovery(EOR),waterflooding,reservoir mapping,and sequestration tracking.The review emphasizes the need for techno-economic analyses using multiphase flow models,particularly in scenarios involving fluid injection for energy storage.Addressing these multiphase flow challenges is crucial for the future of energy diversity and transition initiatives,offering benefits such as financial stability,resilience,sustainability,and reliable supply chains.The first part of this review presents the application of multiphase(typical gas,liquid,solid)flow models and technology for drilling,completion,and injection operations.While the second part reviews the applications of multiphase particulate(nanofluid)flow technology,the use of computational fluid dynamics(CFD),machine learning(ML),and system modeling for multiphase flow models in drilling,completions,and injection operations.
文摘This review addresses the diverse applications of multiphase flows,focusing on drilling,completions,and injection activities in the oil and gas industry.Identifying contemporary challenges and suggesting future research directions,it comprehensively reviews evolving applications in these multidisciplinary topics.In drilling,challenges such as gas kicks,cutting transport,and hole cleaning are explored.The application of immersion cooling technology in surface facilities for gas fields utilized in integrated bitcoin mining is also discussed.Nanotechnology,particularly the use of nanoparticles and nanofluids,shows promise in mitigating particulate flow issues and controlling macroscopic fluid behavior.Nanofluids find applications in drilling for formation strengthening and mitigating formation damage in completions as highlighted in this work,as well as in subsurface injection for enhanced oil recovery(EOR),waterflooding,reservoir mapping,and sequestration tracking.The review emphasizes the need for techno-economic analyses using multiphase flow models,particularly in scenarios involving fluid injection for energy storage.Addressing these multiphase flow challenges is crucial for the future of energy diversity and transition initiatives,offering benefits such as financial stability,resilience,sustainability,and reliable supply chains.In the first part of this review,we presented the application of multiphase(typical gas,liquid,solid)flow models and technology for drilling,completion,and injection operations.This second part of this review presents the applications of multiphase particulate(nanofluid)flow technology for drilling,completion,and injection operations.It aims to identify technology development needs related to multiphase flows,enhancing research endeavors for better cognition and mitigation of the identified issues.The use of computational fluid dynamics(CFD),machine learning(ML),and system modeling for multiphase flow models is also discussed.
基金SERB,DST,Government of India for financial support(EMR/2015/000817)
文摘We investigate the rare baryonic Λ_b→Λl^＋l^- decays in a non-universal Z＇ model, which is one of the wellmotivated extensions of the standard model（SM）. Considering the effects of Z-mediated flavour-changing neutral currents（FCNCs） we analyse the differential decay rate, forward-backward asymmetries and lepton polarisation asymmetries for the Λb→Λl^＋l^- decays. We find significant deviations from their SM predictions, which could indicate new physics arising from the Z gauge boson.
