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Experimental study of core MHD behavior and a novel algorithm for rational surface detection based on profile reflectometry in EAST

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Plasma Science and Technology 2024年第3期26卷 66-75页

作者：叶凯萱周振张涛马九阳王嵎民李恭顺耿康宁吴茗甫文斐黄佳张洋邵林明杨书琪钟富彬高善露喻琳周子强向皓明韩翔张寿彪李国强高翔 the EAST Team Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China Hebei Key Laboratory of Compact Fusion Langfang 065001Peoples Republic of China ENN Science and Technology Development Co. Ltd.Langfang 065001Peoples Republic of China Advanced Energy Research Center Shenzhen UniversityShenzhen 518060People's Republic of China

Microwave reflectometry is a powerful diagnostic that can measure the density profile and localized turbulence with high spatial and temporal resolution and will be used in ITER,so understanding the influence of plasma perturbations on the reflect signal is *** characteristics of the reflect signal from profile reflectometry,the time-of-flight(TOF)signal associated with the MHD instabilities,are investigated in *** a 1D full-wave simulation code by the Finite-DifferenceTime-Domain(FDTD)method,it is well validated that the local density flattening could induce the discontinuity of the simulated TOF signal and an obvious change of reflect *** TOF signals under different types of MHD instabilities(sawtooth,sawtooth precursors and tearing mode)are studied in detail and show agreement with the *** new improved algorithms for detecting and localizing the radial positions of the low-order rational surface,the cross-correlation and gradient threshold(CGT)method and the 2D convolutional neural network approach(CNN)are presented for the first *** is concluded that TOF signal analysis from profile reflectometry can provide a straightforward and localized measurement of the plasma perturbation from the edge to the core simultaneously and may be a complement or correction to the q-profile control,which will be beneficial for the advanced tokamak operation.

关键词： MHD instabilities profile reflectometry rational surface detection convolutional neural network(CNN) EAST tokamak

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A new model of the L–H transition and H-mode power threshold

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Plasma Science and Technology 2018年第9期20卷 12-23页

作者： Xingquan WU Guosheng XU Baonian WAN Jens Juul RASMUSSEN Volker NAULIN Anders Henry NIELSEN Liang CHEN Ran CHEN Ning YAN linming shao Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 People's Republic of China Department of Physics Technical University of Denmark Fysikvej DK-2800 Kgs.-Lyngby Denmark

In order to understand the mechanism of the confinement bifurcation and H-mode power threshold in magnetically confined plasma,a new dynamical model of the L-H transition based on edge instability phase transition（EIPT） has been *** the typical plasma parameters of the EAST tokamak,the self-consistent turbulence growth rate is analyzed using the simplest case of pressure-driven ballooning-type instability,which indicates that the L-H transition can be caused by the stabilization of the edge instability through *** weak E？×？B flow shear in L-mode is able to increase the ion inertia of the electrostatic motion by increasing the radial wave number of the tilted turbulence structures,which play an important role for accelerating the trigger process of EIPT rather than directly to suppress the turbulent *** the acceleration mechanism of E？×？B flow shear,fast L-H and H-L transitions are demonstrated under the control of the input heating *** to the simplified scrape-offlayer boundary condition applied,the ratio between the heating powers at the H-L and L-H transition respectively differs from the ratio by Nusselt *** results of the modeling reveal a scaling of the power threshold of the L-H transition,P_（L-H）？∝？n^（0.76） B^（0.8） for deuterium *** is found finite Larmor radius induces an isotope effect of the H-mode power threshold.

关键词： L-H transition power threshold E×B flow shear turbulence suppression edge instability

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Plasma edge density fluctuation measurements via lithium beam emission spectroscopy on EAST

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Plasma Science and Technology 2022年第5期24卷 94-101页

作者： Donggui WU Guanghai HU S ZOLETNIK Guosheng XU Siye DING Jianbin LIU linming shao Yifeng WANG Ran CHEN Ning YAN Yan CHAO Ping WANG D DUNAI G ANDA Liang CHEN Liang WANG Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031People’s Republic of China University of Science and Technology of China Hefei 230026People’s Republic of China Centre for Energy Research Budapest 1121Hungary Institute of Energy Hefei Comprehensive National Science CenterHefei 230031People’s Republic of China

Accurate and stable measurements of edge density fluctuation with high spatio-temporal resolution have been achieved by the lithium beam emission spectroscopy(Li-BES)diagnostic on experimental and advanced superconducting tokamak(EAST).The new narrower band interference filter exhibits good ability to suppress background emission signal even under strong lithium coating of the *** raw data measured by channels at different spatial locations in avalanche photo diode camera with high chopping frequency show good *** on the detected experimental data,detailed information of density profile and fluctuation structures is obtained.A clear edge coherent mode in the auto-power spectrum is observed in pedestal region,which is regarded as the dominant factor for the strong pedestal density fluctuation *** cross-power spectrum analysis further excludes the additional effects of common-mode noises and non-local perturbation,demonstrating that the detected fluctuation is only caused by local density *** normalized radial and poloidal wave-number spectra can specify the quantitative changes of radial wavenumber(k_(r))and poloidal wavenumber(k_(θ)) during the pedestal density fluctuation *** new Li-BES system,which can provide more accurate experimental data,allows further studies of edge density fluctuation and complex transport process on EAST.

关键词： Li-BES new filter density fluctuation 2D turbulence

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Pseudoeffective thresholds and cohomology of twisted symmetric tensor fields on irreducible Hermitian symmetric spaces

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Science China Mathematics 2024年第11期67卷 2433-2452页

作者： Feng shao Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences

Let X be an irreducible Hermitian symmetric space of compact type(IHSS for short).In this paper,we give the irreducible decomposition of *** a by-product,we give a cohomological characterization of the rank of ***,we introduce pseudoeffective thresholds to measure the bigness of tangent bundles of smooth complex projective varieties precisely and calculate them for irreducible Hermitian symmetric spaces of compact type.

关键词： tangent bundle pseudoeffective threshold irreducible Hermitian symmetric space of compact type (IHSS) multiplicity free action

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Interview with optical scientist and engineer Joseph Braat

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Advanced Photonics 2024年第3期6卷 7-12页

作者： Yifeng shao Delft University of Technology

Joseph Braat(professor emeritus TU Delft and former research fellow at Philips Research) received the 2019 Holst Memorial Lecture Award for his important contributions in to diffractionlimited optical imaging and scan...

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Analysis of spatial distribution characteristics and driving factors of ethnicminority villages in China using geospatial technology and statistical models

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Journal of Mountain Science 2024年第8期21卷 2770-2789页

作者： shao Dandan ZOH Kyungjin Interdisciplinary Program in Landscape Architecture Graduate School of Environmental StudiesSeoul National UniversitySeoul 08826Korea Graduate School of Environmental Studies Seoul National UniversitySeoul 08826Korea

This study aims to reveal the spatial structural characteristics of 1,652 Ethnic-Minority Villages(EMV)in China and to analyze the mechanisms driving their spatial *** are a special type of settlement space that preserve a large number of historical traces of the ethnic culture of ancient *** are important carriers of China’s excellent traditional culture and are key to the implementation of rural revitalization *** this study,1652 EMV in China were selected as the research *** Nearest Neighbor Index,kernel density,and spatial autocorrelation index were employed to reveal the spatial structural characteristics of minority *** network models,spatial lag models,and geographical detectors were used to analyze the formation mechanism of spatial heterogeneity in *** results indicate that:(1)EMV exhibit significant spatial differentiation characterized by“single-core with multiple surrounding sub-centers,”“polarization between east and west,”“decreasing quantity from southwest to east coast to northeast to northwest,”and“large dispersion with small agglomeration.”(2)EMV are mainly distributed in areas rich in intangible cultural heritage,with high vegetation coverage and low altitude,far from central cities,and having limited arable land and an underdeveloped economy and transportation,particularly in shaded or riverbank areas.(3)Distance from the nearest river(X3),distance from central cities(X8),national intangible cultural heritage(X9),and NDVI(X10)were the main driving factors affecting the spatial distribution of EMV,whereas elevation(X1)and GDP(X5)had the weakest *** EMV are a relatively unique territorial spatial unit,the identification of their spatial heterogeneity characteristics not only deepens the research content of settlement geography,but also involves the assessment,protection,and development of Minority Villages,which is of great significance for the inheritance and utilization of excellent

关键词： Ethnic-Minority Villages Spatial structure Settlement geography Neural network model Spatial econometric model GeoDetector

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Topologically Correct Intersection Curves of Two Trimmed Quadrics with Tolerance Control

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Journal of Systems Science & Complexity 2024年第5期37卷 2207-2239页

作者： shao Wenbing CHEN Falai Department of Mathematics University of Science and Technology of China

Surface/surface intersection is a fundamental problem in Compute Aided Design and Geometric Modeling since it is essential to solid modeling, numerically controlled machining, feature recognition, computer animation, etc. In practical applications, quadric surfaces, which are the most basic type of surfaces, are typically bounded surfaces trimmed by a sequence of planes. In this paper,a robust algorithm is proposed for computing the intersection curve segments of two trimmed quadrics based on the parametric representation of the intersection curves of two quadrics. The proposed algorithm guarantees correct topology and ensures that the approximation errors of the end points of the intersection curve segments are less than a given tolerance. The error control is based on an effective solution to a set of polynomial inequality system using the root isolation technique. Some examples are presented to validate the robustness and effectiveness of the proposed algorithm.

关键词： Polynomial inequality system root isolation surface/surface intersection tolerance control trimmed quadrics

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Fear and delay effects on a food chain system with two kinds of different functional responses

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International Journal of Biomathematics 2024年第3期17卷 89-122页

作者： Yuanfu shao College of Science Guilin University of Technology GuilinGuangci 541004P.R.China

For food chain system with three populations,direct predation is the basic interaction between *** species often have different predation functional responses,so a food chain system with Holling-II response for middle predator and Beddinton-DeAngelis response for top predator is *** from direct predation,predator population can significantly impact the survival of prey population by inducing the prey's fear,but the impact often possesses a time *** paper is concentrated to explore how the fear and time delay affect the system stability and the species *** use of Lyapunov functional method and bifurcation theory,the positiveness and boundedness of solutions,local and global behavior of species,the system stability around the equilibrium states and various kinds of bifurcation are ***,some simulations are carried out to validate the main findings and the critical values of the bifurcation parameters of fear and conversion rate are *** is observed that fear and delay can not only stabilize,but also destabilize the system,which depends on the magnitude of the fear and *** system varies from unstable to stable due to the continuous increase of the prey's fear by middle *** fear induced by top predator or small delay of the prey's fear can stabilize the system,while they are sufficiently large,the system stability is to be ***,the conversion rate can also change the stability and even make the species to be *** rich dynamics like multiple stabilities and various types of bistability behaviors are also exhibited,which results in the convergence of the species from one stable equilibrium to another.

关键词： Fear functional response equilibrium bifurcation analysis bi-stability

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Layered double hydroxides functionalization toward rechargeable batteries Author links open overlay panel

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Particuology 2024年第8期91卷 138-154页

作者： Jianxiong Gao Bowen Jin Mingfei shao State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing100029China Renewable Energy Research Institute Quzhou Institute for Innovation in Resource Chemical EngineeringQuzhou324000China

Layered double hydroxides(LDHs),known as typical two-dimensional materials with unique physicochemical properties,are regarded as promising candidates in energy storage ***,some inherent defects,such as poor conductivity and limited active sites,hinder the further development of ***,various functionalization strategies(e.g.,intercalation of guest molecules;metal ions doping and defect introduction of host layer;exfoliation to monolayer;hybridization with functional materials;construction of hierarchical structure;interface engineering and phase transformation)have been used to modify the characteristics of LDHs,which provides guidance for designing novel *** this review,we discuss how these strategies improve the properties of LDH-based materials,which are expected to possess high electronic and ionic conductivity,high specific surface area and high mechanical and chemical stability ***,the application of LDH-based materials in advanced energy conversion and storage techniques,including metal-ions batteries,lithium-sulfur batteries and metal-air batteries,have been comprehensively summarized.

关键词： Layered double hydroxide Functionalization strategy Rechargeable battery

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Aerial target threat assessment based on gated recurrent unit and self-attention mechanism

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Journal of Systems Engineering and Electronics 2024年第2期35卷 361-373页

作者： CHEN Chen QUAN Wei shao Zhuang School of Automation Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Intelligent Control and Decision of Complex Systems Beijing 100081China

Aerial threat assessment is a crucial link in modern air combat, whose result counts a great deal for commanders to make decisions. With the consideration that the existing threat assessment methods have difficulties in dealing with high dimensional time series target data, a threat assessment method based on self-attention mechanism and gated recurrent unit(SAGRU) is proposed. Firstly, a threat feature system including air combat situations and capability features is established. Moreover, a data augmentation process based on fractional Fourier transform(FRFT) is applied to extract more valuable information from time series situation features. Furthermore, aiming to capture key characteristics of battlefield evolution, a bidirectional GRU and SA mechanisms are designed for enhanced ***, after the concatenation of the processed air combat situation and capability features, the target threat level will be predicted by fully connected neural layers and the softmax classifier. Finally, in order to validate this model, an air combat dataset generated by a combat simulation system is introduced for model training and testing. The comparison experiments show the proposed model has structural rationality and can perform threat assessment faster and more accurately than the other existing models based on deep learning.

关键词： target threat assessment gated recurrent unit(GRU) self-attention(SA) fractional Fourier transform(FRFT)

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