Lightweight Spatial-Channel Adaptive Coordination of Multilevel Refinement Enhancement Network for Image Reconstruction

Benefiting from the vigorous development of deep learning, many CNN-based image super-resolution methods have emerged and achieved better results than traditional algorithms. However, it is difficult for most algorithms to adaptively adjust the spatial region and channel features at the same time, let alone the information exchange between them. In addition, the exchange of information between attention modules is even less visible to researchers. To solve these problems, we put forward a lightweight spatial-channel adaptive coordination of multilevel refinement enhancement networks(MREN). Specifically, we construct a space-channel adaptive coordination block, which enables the network to learn the spatial region and channel feature information of interest under different receptive fields. In addition, the information of the corresponding feature processing level between the spatial part and the channel part is exchanged with the help of jump connection to achieve the coordination between the two. We establish a communication bridge between attention modules through a simple linear combination operation, so as to more accurately and continuously guide the network to pay attention to the information of interest. Extensive experiments on several standard test sets have shown that our MREN achieves superior performance over other advanced algorithms with a very small number of parameters and very low computational complexity

Studying dawn-dusk asymmetries of Mercury's magnetotail using MHD-EPIC simulations

MESSENGER has observed a lot of dawn-dusk asymmetries in Mercury's magnetotail, such as the asymmetries of the cross-tail current sheet thickness and the occurrence of flux ropes, dipolarization events and energetic electron injections. In order to obtain a global pictures of Mercury's magnetotail dynamics and the relationship between these asymmetries, we perform global simulations with the magnetohydrodynamics with embedded particle-in-cell (MHD-EPIC) model, where Mercury's magnetotail region is covered by a PIC code. Our simulations show that the dawnside current sheet is thicker, the plasma density is larger, and the electron pressure is higher than the duskside. Under a strong IMF driver, the simulated reconnection sites prefer the dawnside. We also found the dipolarization events and the planetward electron jets are moving dawnward while they are moving towards the planet, so that almost all dipolarization events and high-speed plasma flows concentrate in the dawn sector. The simulation results are consistent with MESSENGER observations

Embedded Kinetic Simulation of Ganymede’s Magnetosphere: Improvements and Inferences

The largest moon in the solar system, Ganymede, is also the only moon known to possess a strong intrinsic magnetic field and a corresponding magnetosphere. Using the new version of Hall magnetohydrodynamic with embedded particle‐in‐cell model with a self‐consistently coupled resistive body representing the electrical properties of the moon’s interior, improved inner boundary conditions, and the flexibility of coupling different grid geometries, we achieve better match of magnetic field with measurements for all six Galileo flybys. The G2 flyby comparisons of plasma bulk flow velocities with the Galileo Plasma Subsystem data support the oxygen ion assumption inside Ganymede’s magnetosphere. Crescent shape, nongyrotropic, and nonisotropic ion distributions are identified from the coupled model. Furthermore, we have derived the energy fluxes associated with the upstream magnetopause reconnection of ∼10−7W/cm2 based on our model results and found a maximum of 40% contribution to the total peak auroral emissions.Key PointsHall MHD‐EPIC model of Ganymede’s magnetosphere uses realistic inner boundary conditions and energy‐conserving PIC schemeIon‐scale kinetics at upstream magnetopause are fully resolved, shown by the nongyrotropic/anisotropic distributionsElectron precipitation of ∼10−7 W/cm2 shows up to half of the peak emission brightness contributed by upstream reconnectionPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151299/1/jgra55029_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151299/2/jgra55029.pd

A case report of multicentric reticulohistiocytosis with atypical cutaneous presentation

Multicentric reticulohistiocytosis (MRH) is a rare systemic disorder characterized by histiocytic hyperplasia that mainly involves the skin, mucous membranes, and joints. The typical clinical features include papules, nodules, and arthritis. MRH lesions are relatively extensive but small and scattered. Joint inflammation is characterized by diffuse symmetric polyarthritis as the first symptom, which can be severe and disabling due to destructive joint changes. MRH is easily misdiagnosed in clinical practice. Here, we report the case of an elderly male patient who presented with polyarticular pain in the hip and interphalangeal joints as the first manifestation, followed by the development of large, isolated, bulging skin nodules, which are atypical MRH lesions. This is rare in all MRH case reports, and we made the correct diagnosis by combining skin histopathology, immunohistochemistry, and other clinical examinations. We performed surgical treatment on the local skin lesions of this patient. This case suggests that clinicians should actively correlate the condition and accurately diagnose MRH when encountering atypical skin changes or other diseases as the first symptom and explore the mechanisms of MRH and other clinical manifestations

Frequency-dependent orthotropic damping properties of Nomex honeycomb composites

In this paper, the orthotropic damping behavior of Nomex honeycomb composites and its causes are investigated. The needed specimen sizes for the measurement of the frequency-dependent transverse shear moduli (TSM) and fundamental damping coefficients of the honeycomb cores were analyzed at first. Then, the effects of cell side length and beam orientation on the orthotropic damping properties were explored. The results reveal that relatively high TSM (GLT) and damping values (ηWT) can be obtained by decreasing the cell side length without adding any additional weight. Damping mechanism analysis indicates that the difference in damping contribution of the interfacial phase to honeycomb core in different directions leads to the orthotropic damping behavior of honeycomb core. This study is helpful to guide the TSM measurement and structure design of honeycomb composites

Rethinking the Metric in Few-shot Learning: From an Adaptive Multi-Distance Perspective

Few-shot learning problem focuses on recognizing unseen classes given a few labeled images. In recent effort, more attention is paid to fine-grained feature embedding, ignoring the relationship among different distance metrics. In this paper, for the first time, we investigate the contributions of different distance metrics, and propose an adaptive fusion scheme, bringing significant improvements in few-shot classification. We start from a naive baseline of confidence summation and demonstrate the necessity of exploiting the complementary property of different distance metrics. By finding the competition problem among them, built upon the baseline, we propose an Adaptive Metrics Module (AMM) to decouple metrics fusion into metric-prediction fusion and metric-losses fusion. The former encourages mutual complementary, while the latter alleviates metric competition via multi-task collaborative learning. Based on AMM, we design a few-shot classification framework AMTNet, including the AMM and the Global Adaptive Loss (GAL), to jointly optimize the few-shot task and auxiliary self-supervised task, making the embedding features more robust. In the experiment, the proposed AMM achieves 2% higher performance than the naive metrics fusion module, and our AMTNet outperforms the state-of-the-arts on multiple benchmark datasets

Global Three‐Dimensional Simulation of Earth’s Dayside Reconnection Using a Two‐Way Coupled Magnetohydrodynamics With Embedded Particle‐in‐Cell Model: Initial Results

We perform a three‐dimensional (3‐D) global simulation of Earth’s magnetosphere with kinetic reconnection physics to study the flux transfer events (FTEs) and dayside magnetic reconnection with the recently developed magnetohydrodynamics with embedded particle‐in‐cell model. During the 1 h long simulation, the FTEs are generated quasi‐periodically near the subsolar point and move toward the poles. We find that the magnetic field signature of FTEs at their early formation stage is similar to a “crater FTE,” which is characterized by a magnetic field strength dip at the FTE center. After the FTE core field grows to a significant value, it becomes an FTE with typical flux rope structure. When an FTE moves across the cusp, reconnection between the FTE field lines and the cusp field lines can dissipate the FTE. The kinetic features are also captured by our model. A crescent electron phase space distribution is found near the reconnection site. A similar distribution is found for ions at the location where the Larmor electric field appears. The lower hybrid drift instability (LHDI) along the current sheet direction also arises at the interface of magnetosheath and magnetosphere plasma. The LHDI electric field is about 8 mV/m, and its dominant wavelength relative to the electron gyroradius agrees reasonably with Magnetospheric Multiscale (MMS) observations.Key PointsWe performed a 1 h long global simulation of Earth’s magnetosphere with kinetic modeling of the dayside reconnectionCrater FTE is found at the early stage of a flux rope formationKinetic phenomena are found from the global simulationPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139959/1/jgra53816_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139959/2/jgra53816.pd

Extended magnetohydrodynamics with embedded particle‐in‐cell simulation of Ganymede’s magnetosphere

We have recently developed a new modeling capability to embed the implicit particle‐in‐cell (PIC) model iPIC3D into the Block‐Adaptive‐Tree‐Solarwind‐Roe‐Upwind‐Scheme magnetohydrodynamic (MHD) model. The MHD with embedded PIC domains (MHD‐EPIC) algorithm is a two‐way coupled kinetic‐fluid model. As one of the very first applications of the MHD‐EPIC algorithm, we simulate the interaction between Jupiter’s magnetospheric plasma and Ganymede’s magnetosphere. We compare the MHD‐EPIC simulations with pure Hall MHD simulations and compare both model results with Galileo observations to assess the importance of kinetic effects in controlling the configuration and dynamics of Ganymede’s magnetosphere. We find that the Hall MHD and MHD‐EPIC solutions are qualitatively similar, but there are significant quantitative differences. In particular, the density and pressure inside the magnetosphere show different distributions. For our baseline grid resolution the PIC solution is more dynamic than the Hall MHD simulation and it compares significantly better with the Galileo magnetic measurements than the Hall MHD solution. The power spectra of the observed and simulated magnetic field fluctuations agree extremely well for the MHD‐EPIC model. The MHD‐EPIC simulation also produced a few flux transfer events (FTEs) that have magnetic signatures very similar to an observed event. The simulation shows that the FTEs often exhibit complex 3‐D structures with their orientations changing substantially between the equatorial plane and the Galileo trajectory, which explains the magnetic signatures observed during the magnetopause crossings. The computational cost of the MHD‐EPIC simulation was only about 4 times more than that of the Hall MHD simulation.Key PointsFirst particle‐in‐cell simulation of Ganymede’s magnetosphereThe MHD‐EPIC algorithm makes global kinetic simulations affordableMHD‐EPIC simulation suggests that Galileo observed a flux transfer event during the G8 flybyPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135161/1/jgra52397.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135161/2/jgra52397_am.pd