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Natural convective flow of a magneto-micropolar fluid along a vertical plate

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Propulsion and Power Research 2018年第1期7卷 43-51页

作者： M.Ferdows d.liu College of Engineering and Science Louisiana Tech UniversityRustonLouisiana 71272USA department of Applied Mathematics University of DhakaDhaka-1000Bangladesh

This paper presents a numerical study of natural convective flow of an electrically conducting viscous micropolar fluid past a vertical plate. Internal heat generation (IHG) versus without IHG in the medium are discussed in the context of corresponding similarity solutions. Results are presented in terms of velocity, angular velocity, temperature, skin friction in tabular forms, local wall-coupled stress, and Nusselt number. Computations have been accomplished by parametrizing the micropolar, micro-rotation, magnetic field, suction parameters, and the Prandtl number. Several critical issues are addressed at the end of the paper with reference to a previous study by El-Hakiem. The study is relevant to high-temperature electromagnetic materials fabrication systems.

关键词： Natural convection Thermal boundary layer Micropolar fluid Similarity transformation Internal heat generation

Analysis of the distribution,Rotation and Scale Characteristics of Solar Wind Switchbacks:Comparison between the First and Second Encounters of Parker Solar Probe

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Research in Astronomy and Astrophysics 2022年第3期22卷 178-185页

作者： Ming-Ming Meng Ying d.liu Chong Chen Rui Wang State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The S-shaped magnetic structure in the solar wind formed by the twisting of magnetic field lines is called a switchback,whose main characteristics are the reversal of the magnetic field and the significant increase in the solar wind radial *** identify 242 switchbacks during the first two encounters of Parker Solar *** methods are applied to analyze the distribution and the rotation angle and direction of the magnetic field rotation of the *** diameter of switchbacks is estimated with a minimum variance analysis(MVA)method based on the assumption of a cylindrical magnetic *** also make a comparison between switchbacks from inside and the boundary of coronal *** main conclusions are as follows:(1)the rotation angles of switchbacks observed during the first encounter seem larger than those of the switchbacks observed during the second encounter in general;(2)the tangential component of the velocity inside the switchbacks tends to be more positive(westward)than in the ambient solar wind;(3)switchbacks are more likely to rotate clockwise than counterclockwise,and the number of switchbacks with clockwise rotation is 1.48 and 2.65 times those with counterclockwise rotation during the first and second encounters,respectively;(4)the diameter of switchbacks is about 10;km on average and across five orders of magnitude(10^(3)–10^(7)km).

关键词： ISM:magnetic fields methods:statistical (Sun:)solar wind

High-resolution Observations of Clustered dynamic Extreme-Ultraviolet Bright Tadpoles Near the Footpoints of Corona Loops

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Research in Astronomy and Astrophysics 2024年第12期24卷 93-106页

作者： Rui Wang Ying d.liu L.P.Chitta Huidong Hu Xiaowei Zhao State Key Laboratory of Space Weather National Space Science CenterChinese Academy of Sciences Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of Sciences University of Chinese Academy of Sciences Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3 Key Laboratory of Space Weather National Satellite Meteorological Center (National Center for Space Weather) School of Earth and Space Sciences Peking University

An extreme ultraviolet（EUV） close-up view of the Sun offers unprecedented detail of heating events in the solar corona. Enhanced temporal and spatial images obtained by the Solar Orbiter during its first science perihelion enabled us to identify clustered EUV bright tadpoles（CEBTs） occurring near the footpoints of coronal *** SdO/AIA observations, we determine the altitudes of six distinct CEBTs by stereoscopy, ranging from　～1300 to 3300 km. We then notice a substantial presence of dark, cooler filamentary structures seemingly beneath the CEBTs, displaying periodic up-and-down motions lasting 3–5 minutes. This periodic behavior suggests an association of the majority of CEBTs with Type I spicules. Out of the ten selected CEBTs with fast downward velocity, six exhibit corrected velocities close to or exceeding 50 km s-1. These velocities notably surpass the typical speeds of Type I spicules. We explore the generation of such velocities. It indicates that due to the previous limited observations of spicules in the EUV wavelengths, they may reveal novel observational features beyond our current understanding. Gaining insights into these features contributes to a better comprehension of small-scale coronal heating dynamics.

关键词： Sun: activity Sun: atmosphere Sun: corona Sun: transition region

Pinpointing the sources and measuring the lengths of the principal rivers of the world

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International Journal of digital Earth 2009年第1期2卷 80-87页

作者： S.liu P.Lu d.liu P.Jin W.Wang Institute of Remote Sensing Applications Chinese Academy of SciencesDatun RoadChaoyang DistrictBeijing 100101China China Association for Science and Technology 86 Southern Colleges RoadHaidian DistrictBeijing 100081China China Aero-Geophysical Survey&Remote Sensing Centre for Land and Resources 31 Colleges RoadHaidian DistrictBeijing 100083China School of Environment and Nature Resources Renmin University of China59 Zhongguancun StreetBeijing 100872China

Cultures throughout the world are associating with the *** depend upon the rivers and their tributaries for food,water,transport,and many other aspects of their daily ***,human beings have not calculated the accurate lengths for the great rivers even *** lengths of the rivers are very different in popular textbooks,magazines,atlases and encyclopedias,*** accurately determine the lengths of the principal rivers of the world,the combination of satellite image analysis and field investigations to the source regions is proposed in this *** lengths of the Nile,Amazon,Yangtze,Mississippi,Yellow,Ob,Yenisey,Amur,Congo and Mekong,with lengths over or close to 5000 km,were calculated using the proposed *** results may represent the most reliable and accurate lengths of the principal rivers of the world that are currently achievable.

关键词： principal rivers of the world sources pinpointing lengths measuring satellite remote sensing field explorations

A Code that Simulates Fast-Ion dα and Neutral Particle Measurements

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Communications in Computational Physics 2011年第8期10卷 716-741页

作者： W.W.Heidbrink d.liu Y.Luo E.Ruskov B.Geiger department of Physics and Astronomy University of CaliforniaIrvineCaliforniaCA 92697USA Max-Planck Institute fur Plasmaphysik GarchingGermany department of Physics University of Wisconsin-MadisonMadisonWI 53706USA Tri Alpha Energy Corporation 27211 BurbankFoothill RanchCA 92610USA

A code that models signals produced by charge-exchange reactions between fast ions and injected neutral beams in tokamak plasmas is *** the fastion distribution function as input,the code predicts the efflux to a neutral particle analyzer(NPA)diagnostic and the photon radiance of Balmer-alpha light to a fastion dα(FIdA)*** with both the primary injected neutrals and with the cloud of secondary"halo"neutrals that surround the beam are *** calculation of the fraction of neutrals that occupy excited atomic states(the collisionalradiative transition equations)is an important element of the *** with TRANSP output and other tests verify the *** selection of grid size and other parameters facilitate efficient *** output of the code has been validated by FIdA measurements on dIII-d but further tests are warranted.

关键词： Fast ions

Propagation of large-scale solar wind events in the outer heliosphere from a numerical MHd simulation

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Earth and Planetary Physics 2021年第3期5卷 223-231页

作者： XiaoCheng Guo YuCheng Zhou Chi Wang Ying dliu State Key Laboratory of Space Weather National Space Science CenterChinese Academy of ScienceBeijing 100190China College of Earth and Planetary Sciences University of Chinese Academy of SciencesChinese Academy of ScienceBeijing 100049China

Voyager 1 occasionally detected sudden jumps of the local interstellar magnetic field strength since its heliopause crossing in August *** events were believed to be associated with outward propagating solar wind shocks originating in the inner *** we investigate the correlation between interstellar shocks and large-scale solar wind events by means of numerical MHd *** solar wind is simplified as a symmetric flow near the equatorial plane,and the interstellar neutrals are treated as a constant flow with a fixed density distribution along the upwind direction of the local interstellar *** charge exchanges between the solar wind plasma and the interstellar neutrals are taken into *** a heliocentric distance of 1 AU,the solar wind data from OMNI,STEREO A and B during the period between 2010 and 2017 are used as the inner boundary conditions to drive the *** simulation results showed that the solar wind gradually merges into large-scale structures as the radial distance increases,consistent with observations by New *** propagating into the inner heliosheath,the shocks are fully developed and the corresponding pressure pulses roughly agree with the observations by Voyager 2 in the inner *** arrival of the shocks beyond the heliopause is estimated and found to be consistent with the observed signatures of interstellar shocks by Voyager *** possible origins of interstellar shocks in the inner heliosheath are discussed based on the simulation.

关键词： MHd outer heliosphere solar wind interstellar medium shocks Voyager

Probing a dissipative Phase Transition with a Trapped Ion through Reservoir Engineering

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Chinese Physics Letters 2022年第2期39卷 10-14页

作者： M.-L.Cai Z.-d.liu Y.Jiang Y.-K.Wu Q.-X.Mei W.-d.Zhao L.He X.Zhang Z.-C.Zhou L.-M.duan Center for Quantum Information Institute for Interdisciplinary Information SciencesTsinghua UniversityBeijing 100084China department of Physics Renmin UniversityBeijing 100084China Beijing Academy of Quantum Information Sciences Beijing 100193China

dissipation is often considered as a detrimental effect in quantum systems for unitary quantum ***,it has been shown that suitable dissipation can be useful resources in both quantum information and quantum ***,we propose and experimentally simulate a dissipative phase transition(dPT)model using a single trapped ion with an engineered *** show that the ion’s spatial oscillation mode reaches a steady state after the alternating application of unitary evolution under a quantum Rabi model Hamiltonian and sideband cooling of the *** average phonon number of the oscillation mode is used as the order parameter to provide evidence for the *** work highlights the suitability of trapped ions for simulating open quantum systems and shall facilitate further investigations of dPT with various dissipation terms.

关键词： quantum unitary oscillation

Theoretical and Experimental Studies on Threshold of the Laser-induced Air Breakdown

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Theoretical and Experimental Studies on Threshold of the Las...

VLSI PERFORMANCE ANALYSIS METHOd FOR LOW-VOLTAGE CIRCUIT OPERATION

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作者： d.liu C.S.Chen B.Y.Man X.Meng X.J.Chen College of Physics and Electronics Shandong Normal University

The threshold of laser-induced breakdown of air is determined in experiment and a new theoretical model is established to calculate *** model divides the breakdown process into two stages:the first one is multiphoton ionization process(MI) which provides enough "seed electrons" to initiate the next stage and the second one is predominated by cascade ionization(CI)which continues to produce free electrons geometrically until the critical free-electron density for breakdown is *** solve the differentia]equation set under our laboratory *** is found that the time node dividing the two stages is at about 7.6 ns,and the calculated threshold is in good agreement with the experiment.

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VLSI PERFORMANCE ANALYSIS METHOD FOR LOW-VOLTAGE CIRCUIT OPE...