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SR-AFU: super-resolution network using adaptive frequency component upsampling and multi-resolution features

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Frontiers of Computer Science 2023年第1期17卷 123-132页

作者： Ke-Jia CHEN mingyu wu Yibo ZHANG Zhiwei CHEN School of Computer Science Nanjing University of Posts and TelecommunicationsNanjing 210023China Jiangsu Key Laboratory of Big Data Security&Intelligent Processing Nanjing University of Posts and TelecommunicationsNanjing 210023China College of Telecommunications and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China

Image super-resolution (SR) is one of the classic computer vision tasks. This paper proposes a super-resolution network based on adaptive frequency component upsampling, named SR-AFU. The network is composed of multiple cascaded dilated convolution residual blocks (CDCRB) to extract multi-resolution features representing image semantics, and multiple multi-size convolutional upsampling blocks (MCUB) to adaptively upsample different frequency components using CDCRB features. The paper also defines a new loss function based on the discrete wavelet transform, making the reconstructed SR images closer to human perception. Experiments on the benchmark datasets show that SR-AFU has higher peak signal to noise ratio (PSNR), significantly faster training speed and more realistic visual effects compared with the existing methods.

关键词： super-resolution multi-resolution features adaptive frequency upsampling wavelet transformation

Scalings for the Alfvén-cyclotron instability in a bi-kappa plasma

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Earth and Planetary Physics 2023年第6期7卷 631-639页

作者： YueQun Lou Xing Cao mingyu wu BinBin Ni TieLong Zhang Shenzhen Key Laboratory of Numerical Prediction for Space Storm Institute of Space Science and Applied TechnologyHarbin Institute of TechnologyShenzhen 518055China Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China Space Research Institute Austrian Academy of SciencesGraz 8042Austria

The particle velocity distribution in space plasma usually exhibits a non-Maxwellian high-energy tail that can be well modeled by kappa *** this study,we focus on the growth rates of the Alfvén-cyclotron instability driven by ion temperature anisotropy in a kappa *** solving the kinetic linear dispersion equation,we explore the sensitivity of growth rates to the spectral indexκof a bi-kappa distribution under different plasma conditions,including a variety of plasma beta β_(hp) and temperature anisotropy A_(hp) values of hot ***,a concise,analytic scaling formula is derived that relates the dimensionless maximum growth rate to three independent variables:the spectral index and the plasma beta and temperature anisotropy of hot *** results show that as theκ-value increases,the instability bandwidth narrows and the maximum growth rate increases *** higherβ_(hp)and A_(hp)′the maximum instability undergoes a sharp increase as *** our fits of dimensionless maximum growth rates are compared with solutions to kinetic linear dispersion theory,the results generally exhibit good agreement between *** under the circumstances of largeκ-values and highβ_(hp)and A_(hp)′the scalings of maximum growth rates primarily accurately model the numerical *** analytic expressions can readily be used in large-scale models of the Earth’s magnetosphere to understand wave generation due to the Alfvén-cyclotron instability.

关键词： Alfvén-cyclotron instability kappa distribution kinetic linear dispersion theory scaling formula

Statistical study of magnetic holes in the upstream region of Mercury’s bow shock

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Earth and Planetary Physics 2024年第2期8卷 326-337页

作者： GuoQiang Wang SuDong Xiao mingyu wu YuanQiang Chen TieLong Zhang Institute of Space Science and Applied Technology Harbin Institute of TechnologyShenzhen 518055China Shenzhen Key Laboratory of Numerical Prediction for Space Storm Harbin Institute of TechnologyShenzhen 518055China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China Space Research Institute Austrian Academy of SciencesGrazAustria

Magnetic holes are magnetic depression structures that exist widely in many plasma *** magnetic holes with durations of>1 s in the solar wind at Mercury’s orbit have drawn much attention,but the properties of the magnetic holes with shorter durations are still ***,we investigate the magnetic holes with durations of 0.1-100 s in the upstream region of Mercury’s bow shock based on observations by the MESSENGER(MErcury Surface,Space ENvironment,GEochemistry,and Ranging)*** can be divided into two groups according to the distribution of their duration:small-duration magnetic holes(SDMHs,0.6 s).The duration of each group approximately obeys a log-normal distribution with a median of~0.25 s and 3 s,*** 1.7%(32.6%)of the SDMHs(LDMHs)reduce the magnetic field strength by more than 50%.For both groups,some structures have a linear or quasi-linear polarization,whereas others have an elliptical *** magnetic hole events in both groups tend to have a higher rate of occurrence when the interplanetary magnetic field strength is *** occurrence rates are also affected by Mercury’s foreshock,which can increase(decrease)the occurrence rate of the SDMHs(LDMHs).This finding suggests that Mercury’s foreshock might be one source of the SDMHs and that the foreshock can destroy some *** observations suggest that a new group of magnetic holes with durations of<0.6 s exist in the upstream region of Mercury’s bow shock.

关键词： magnetic hole solar wind Mercury foreshock

Electrostatic Structure of the Electron Phase-space Holes Generated by the Electron Two-stream Instability with a Finite Width

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空间科学学报 2017年第5期37卷 517-523页

作者： SANG Longlong wu mingyu LU Quanming CAS Key Laboratory of Geospace Environment School of Earth and Space Sciences University of Science and Technology of China

Space satellite observations in an electron phase-space hole(electron hole) have shown that bipolar structures are discovered at the parallel cut of parallel electric field, while unipolar structures spring from the parallel cut of perpendicular electric field. Particle-in-cell(PIC) simulations have demonstrated that the electron bi-stream instability induces several electron holes during its nonlinear evolution. However, how the unipolar structure of the parallel cut of the perpendicular electric field formed in these electron holes is still an unsolved problem,especially in a strongly magnetized plasma(Ω_e >ω_(pe), where Ω_e is defined as electron gyrofrequency and ω_(pe) is defined as plasma frequency, respectively). In this paper, with two-dimensional(2D) electrostatic PIC simulations, the evolution of the electron two-stream instability with a finite width in strongly magnetized plasma is investigated. Initially, those conditions lead to monochromatic electrostatic waves, and these waves coalesce with each other during their nonlinear evolution. At last, a solitary electrostatic structure is formed. In such an electron hole, a bipolar structure is formed in the parallel cut. of parallel electric field, while a unipolar structure presents in the parallel cut of perpendicular electric field.

关键词： Electron phase-space hole Two-stream instability PIC simulation

Responses of the field-aligned currents in the plasma sheet boundary layer to a geomagnetic storm

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Earth and Planetary Physics 2023年第5期7卷 558-564页

作者： YuanQiang Chen mingyu wu YangJun Chen SuDong Xiao GuoQiang Wang TieLong Zhang Shenzhen Key Laboratory of Numerical Prediction for Space Storm Harbin Institute of TechnologyShenzhen 518055China Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Chinese Academy of Sciences Center for Excellence in Comparative PlanetologyHefei 230026China Space Research Institute Austrian Academy of SciencesGraz 8042Austria

Geomagnetic storms can result in large magnetic field disturbances and intense currents in the magnetosphere and even on the *** an important medium of momentum and energy transport among the solar wind,magnetosphere,and ionosphere,field-aligned currents(FACs)can also be strengthened in storm *** study shows the responses of FACs in the plasma sheet boundary layer(PSBL)observed by the Magnetospheric Multiscale(MMS)spacecraft in different phases of a large storm that lasted from May 27,2017,to May 29,*** of the FACs were carried by electrons,and several FACs in the storm time also contained sufficient ion *** FAC magnitudes were larger in the storm than in the quiet period,and those in the main phase were the *** this case,the direction of the FACs in the main phase showed no preference for tailward or earthward,whereas the direction of the FACs in the recovery phase was mostly *** results suggest that the FACs in the PSBL are closely related to the storm and could be driven by activities in the tail region,where the energy transported from the solar wind to the magnetosphere is stored and released as the storm is ***,the FACs are an important medium of energy transport between the tail and the ionosphere,and the PSBL is a significant magnetosphere–ionosphere coupling region in the nightside.

关键词： field-aligned currents plasma sheet boundary layer geomagnetic storm

Turbulence in the near-Venusian space: Venus Express observations

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Earth and Planetary Physics 2020年第1期4卷 82-87页

作者： SuDong Xiao mingyu wu GuoQiang Wang Geng Wang YuanQiang Chen TieLong Zhang Harbin Institute of Technology Shenzhen 518055China Space Science Institute Macao University of Science and TechnologyMacao 999078China Chinese Academy of Sciences Key Laboratory of Geospace Environment University of Science and Technology of ChinaHefei 230026China Space Research Institute Austrian Academy of SciencesGraz 8042Austria

With Venus Express magnetic field measurements at 32 Hz from 2006 to 2012, we investigate statistically the magnetic fluctuations in the near-Venusian space. The global spatial distribution of their spectral scaling features is presented in MHD and kinetic regimes. It can be observed that turbulence is a common phenomenon in the solar wind in both regimes. The solar wind MHD turbulence is modified at the Venusian bow shock;MHD turbulence is absent in the Venusian magnetosheath but present at the magnetosheath boundary layer. Pre-existing kinetic turbulence from the far upstream solar wind is modified in the near solar wind region, while kinetic turbulence can be extensively observed throughout the Venusian magnetosheath and in some regions of the induced magnetosphere. Our results reveal that, in the near-Venusian space, energy cascade can be developed at the boundary between magnetosheath and wake, and the turbulence-related dissipation of magnetic energy occurs extensively in the magnetosheath and the induced magnetosphere.

关键词： turbulence near-Venusian space kinetic effects Venus Express

Biotinylated dextran amine tracing of nerve tracts determines regeneration of corticospinal tracts after neural stem cell transplantation

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Neural Regeneration Research 2011年第28期6卷 2183-2187页

作者： Jun wu Fenghua Chen mingyu Zhang Tao Song Jinfang Liu Jiasheng Fang Department of Neurosurgery Xiangya Hospital Central South University Changsha 410008 Hunan Province China

We investigated regeneration of the corticospinal tract and rearrangement of corticospinal nerves after spinal cord injury by biotinylated dextran amine （BDA） nerve tract tracing after neural stem cell transplantation. Neural stem cell transplantation increased motor function scores of rats at 3 weeks after spinal cord transection injury at the thoracic 10 segment. A proportion of BDA-labeled corticospinal tract regenerated through the spinal cord injury site at 12 weeks after transplantation. Electron microscopy revealed that the regenerated BDA-labeled nerve terminals formed new synaptic connections with neurons at the distal end of the injured site. These findings indicate that BDA nerve tract tracing effectively provides anatomic and morphological evidence of recovery after spinal cord injury.

关键词： nerve tract tracing neural stem cells transplantation spinal cord injury corticospinal tract biotinylated dextran amine neural regeneration

Tanshinone IIA ameliorates energy metabolism dysfunction of pulmonary fibrosis using 13C metabolic flux analysis

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Journal of Pharmaceutical Analysis 2024年第2期14卷 244-258页

作者： Baixi Shan Haoyan Zhou Congying Guo Xiaolu Liu mingyu wu Rao Zhai Jun Chen State Key Laboratory of Natural Medicines China Pharmaceutical UniversityNanjing210009China Department of Pharmacognosy School of Traditional Chinese PharmacyChina Pharmaceutical UniversityNanjing210009China

Evidence indicates that metabolic reprogramming characterized by the changes in cellular metabolic patterns contributes to the pathogenesis of pulmonary fibrosis (PF). It is considered as a promising therapeutic target anti-PF. The well-documented against PF properties of Tanshinone IIA (Tan IIA) have been primarily attributed to its antioxidant and anti-inflammatory potency. Emerging evidence suggests that Tan IIA may target energy metabolism pathways, including glycolysis and tricarboxylic acid (TCA) cycle. However, the detailed and advanced mechanisms underlying the anti-PF activities remain obscure. In this study, we applied [U-13C]-glucose metabolic flux analysis (MFA) to examine metabolism flux disruption and modulation nodes of Tan IIA in PF. We identified that Tan IIA inhibited the glycolysis and TCA flux, thereby suppressing the production of transforming growth factor-β1 (TGF-β1)-dependent extracellular matrix and the differentiation and proliferation of myofibroblasts in vitro. We further revealed that Tan IIA inhibited the expression of key metabolic enzyme hexokinase 2 (HK2) by inhibiting phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/hypoxia-inducible factor 1α (HIF-1α) pathway activities, which decreased the accumulation of abnormal metabolites. Notably, we demonstrated that Tan IIA inhibited ATP citrate lyase (ACLY) activity, which reduced the collagen synthesis pathway caused by cytosol citrate consumption. Further, these results were validated in a mouse model of bleomycin-induced PF. This study was novel in exploring the mechanism of the occurrence and development of Tan IIA in treating PF using 13C-MFA technology. It provided a novel understanding of the mechanism of Tan IIA against PF from the perspective of metabolic reprogramming.

关键词： Pulmonary fibrosis Tanshinone IIA 13C-metabolic flux analysis Metabolic reprogramming

Effect of Ion Dynamics on the Evolution of Electron Phase-space Holes

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空间科学学报 2013年第4期33卷 413-417页

作者： WANG Peiran LU Quanming wu mingyu WANG Shui CAS Key Laboratory of Basic Plasma Physics Department of Geophysics and Planetary ScienceUniversity of Science and Technology of China

The evolution of two-dimensional（2D） electron phase-space holes（electron holes） has been previously investigated with electrostatic Particle-in-Cell（PIC） simulations,which neglect ion *** electron holes are found to be unstable to the transverse instability,and their evolution is determined by the combined action between the transverse instability and the stabilization by the background magnetic *** this paper,the effect of ion dynamics on the evolution of an electron hole is *** weakly magnetized plasma(Ωeωpe),the electron hole is broken due to the lower hybrid waves, and its evolution is much faster.

关键词： Ion dynamics Electron holes Transverse instability Magnetized plasma