Heating of multi‐species upflowing ion beams observed by Cluster on March 28, 2001

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149495/1/epp320083.pd

Detection of magnetospheric ion drift patterns at Mars

Mars lacks a global magnetic field, and instead possesses small-scale crustal magnetic fields, making its magnetic environment fundamentally different from intrinsic magnetospheres like those of Earth or Saturn. Here we report the discovery of magnetospheric ion drift patterns, typical of intrinsic magnetospheres, at Mars usingmeasurements fromMarsAtmosphere and Volatile EvolutioNmission. Specifically, we observewedge-like dispersion structures of hydrogen ions exhibiting butterfly-shaped distributions within the Martian crustal fields, a feature previously observed only in planetary-scale intrinsic magnetospheres. These dispersed structures are the results of driftmotions that fundamentally resemble those observed in intrinsic magnetospheres. Our findings indicate that the Martian magnetosphere embodies an intermediate case where both the unmagnetized and magnetized ion behaviors could be observed because of the wide range of strengths and spatial scales of the crustal magnetic fields around Mars.Comment: 10 pages, 6 figure

Evidence for lunar tide effects in Earth’s plasmasphere

Tides are universal and affect spatially distributed systems, ranging from planetary to galactic scales. In the Earth–Moon system, effects caused by lunar tides were reported in the Earth’s crust, oceans, neutral gas-dominated atmosphere (including the ionosphere) and near-ground geomagnetic field. However, whether a lunar tide effect exists in the plasma-dominated regions has not been explored yet. Here we show evidence of a lunar tide-induced signal in the plasmasphere, the inner region of the magnetosphere, which is filled with cold plasma. We obtain these results by analysing variations in the plasmasphere’s boundary location over the past four decades from multisatellite observations. The signal possesses distinct diurnal (and monthly) periodicities, which are different from the semidiurnal (and semimonthly) variations dominant in the previously observed lunar tide effects in other regions. These results demonstrate the importance of lunar tidal effects in plasma-dominated regions, influencing understanding of the coupling between the Moon, atmosphere and magnetosphere system through gravity and electromagnetic forces. Furthermore, these findings may have implications for tidal interactions in other two-body celestial systems

Novel Learning Algorithm based on BFE and ABC for Process Neural Network and its Application

In order to improve the generalization capability of process neural network (PNN), a novel learning algorithm is proposed based on basis function expansion (BFE) algorithm and artificial bee colony (ABC) algorithm, named BFE-ABC algorithm. First, the input functions and weight functions are simplified through BFE algorithm. The parameter space is transformed from function space to real number space in this way. Then, the PNN is designed to parametric representation through introducing two Boolean variables and one multidimensional parameter. At last, the multidimensional parameter composed of hidden neurons, expansion items and connection weights is optimized in real number space by ABC algorithm. BFE-ABC algorithm overcomes the premature problem and realizes the global optimization of the structure, connection weights and function expansion form at the same time. It is validated through the prediction experiment of Mackey-Glass chaotic time series. The test results in cylinder head temperature prediction prove the superiority of BFE-ABC algorithm over traditional learning algorithm and the applicability to time-dependent parameter prediction

An Overview of Anthropological Regional Studies

Abstract Regional studies in anthropology are vital to the development of the discipline, for they supply anthropology with an approach that moves from individual cases to a holistic understanding of a region. Western anthropologists’ interests in researching non-western regions started as early as the Age of Discovery, and regional studies in anthropology, in the United States in particular, are well-organized and systematic. In China, regional studies serve to transcend China’s traditional village studies to understand Chinese civilization as a whole. Following this approach, several paradigms, including Skinner’s model, were proposed and regional studies were part of Fei Xiaotong’s entire academic life. Globalization poses both challenges and opportunities to regional studies while bringing new visions to its practice in China

Numerical Study of Heat and Mass Transfer in the Original Structure and Homogeneous Substitution Model for Three Dimensional Porous Metal Foam

In many applications, such as the miniaturization and cooling of high-power electronics in aerospace, a new thermal management solution is needed, and metal foam radiators may be a valuable solution. In this work, X-ray scanning was applied to obtain the original structure of the metal foam. The real structure calculation model of the metal foam was obtained through a series of modeling, and high-precision numerical simulation was built to study heat and mass transfer in the original structure and homogeneous substitution model for three-dimensional porous metal foam. The distribution of velocity, pressure and temperature field is investigated. The results show that the heat transfer characteristics increase and flow resistance decreases with an increase in the Reynolds number. The heat transfer performance and flow resistance increase with the decrease of porosity. The porous media homogenization model can be consistent with the original real calculation results of metal foam by using appropriate values of resistance coefficient and porosity. The variation of resistance coefficient and porosity with the working condition in the porous homogenization model is identified

Poleward-Moving Black Aurora Associated with Impulse-Excited Field-Line Resonances in the Dawnside Sector: THEMIS and Ground Observations

The black aurora is a distinct phenomenon characterized by spatially well-defined regions where the diffuse auroral luminosity decreases notably. Typically, black auroras present as arcs moving at lower velocities, patches with higher moving speeds, and arc segments. However, the mechanism behind black auroras remains unclear. In this paper, we present a novel observation of a poleward-moving black auroral arc associated with impulse-excited field-line resonances in the dawnside sector from the multi-spacecraft THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission, equivalent ionospheric currents, and a conjugated all-sky imager. The field-line resonance velocities exhibit periodic vorticity, which correspond to periodic poleward-moving bands of enhanced FACs. Based on the relatively large reduction in luminosity, we conclude that the poleward-moving black auroral arc was most likely caused by downward FACs associated with field-line resonances

Equatorward Moving Auroral Arcs Associated with Impulse-Excited Field Line Resonance

The theory of equatorward moving east-west elongated auroral arcs associated with field line resonance (FLR) has been proposed for decades. However, confirming this theory requires in-situ observations of FLR within the magnetosphere and simultaneous all-sky imager observations of equatorward moving auroral arcs near satellite footpoints. In this study, we present the first observations of multiple equatorward moving auroral arcs related to impulse-excited FLR, using datasets from the WIND, Geotail satellites, and an all-sky imager at China’s Zhongshan Station (ZHS) in Antarctica. In the presented event, the ultra-low-frequency waves associated with solar wind dynamic pressure pulse was mainly toroidal mode, which is consistent with the theory that the toroidal mode waves usually related with external source. The all-sky imager located in Zhongshan station recorded several equatorward moving auroral arcs, followed by reverse propagating ones. The latitudinal width of the equatorward moving auroral arcs was on the order of 25 km and had an average equatorward propagation of ~0.37 km/s, which is very similar to the value from previous work. To better illustrate the observed evolution of auroral arcs related with the FLRs we proposed a simple model to evaluate the FACs induced by the FLRs in different latitudes. The latitudinal distribution evolution of FACs agrees well with the ground-based optical observations