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Recent progress in the interaction between energetic particles and tearing modes

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National Science Review 2022年第11期9卷 240-261页

作者： Huishan cai Ding Li Chinese Academy of Sciences Key Laboratory of Geospace Environment School of Nuclear Sciences and TechnologyUniversity of Science and Technology of China Institute of Physics Chinese Academy of Sciences Songshan Lake Materials Laboratory

The dynamics of energetic particles and tearing modes and the interactions between them are of great significance for magnetically confined fusion plasmas. In this review, we focus on these issues in the context of tokamak plasmas. The interaction between energetic particles and tearing modes is considered from two perspectives:(i) the influence of energetic particles on tearing modes and(ii) the transport of energetic particles by tearing modes. The influence of energetic particles on tearing modes is described on the basis of a general dispersion relation for tearing modes. The effects of energetic particles are considered separately in the outer region and the island region of a tearing mode. The physics mainly results from the modification of the perturbed parallel current by energetic particles without wave–particle resonance. In addition, the resonance between energetic particles and tearing modes is also reviewed. For the transport of energetic particles, transport of both circulating and trapped energetic particles by tearing mode is reviewed. Our descriptions of physical phenomena here are based on an analytical approach, while the experiments and simulations are used to illustrate and confirm our results. Finally, a number of open issues are discussed.

关键词： magnetically confined plasma energetic particle tearing mode transport confinement tokamak

Cavitation dynamics in a vitrimer

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Acta Mechanica Sinica 2021年第5期37卷 767-772,I0001页

作者： Zhaoqiang Song Shengqiang cai Department of Mechanical and Aerospace Engineering University of CaliforniaSan DiegoLa JollaCA 92093USA

Vitrimer is a polymer network with dynamic covalent bonds,which can be dynamically broken and *** to the dynamic covalent bonds,vitrimer behaves like an elastomer at high deformation rate or low temperature but a viscous fluid at low deformation rate or high *** this article,we study the cavitation dynamics in a vitrimer,which is known to be an important damaging mechanism in *** the formulation,a nonlinear three-dimensional rate-dependent constitutive model for the vitrimer is adopted,in which both of the strain stiffening and the kinetics of dynamic exchanging reactions are *** theory predicts strong dependence of the cavitation dynamics on the loading *** computational results may help to reveal some critical insights into the rate-dependent fracture in vitrimer.

关键词： Vitrimer Cavitation dynamics Strain stiffening Viscoelasticity

Orderliness of Hydrocarbon Accumulation Distribution in Rift Basins of Eastern China

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Acta Geologica Sinica(English Edition) 2012年第3期86卷 779-787页

作者： cai Xiyuan China Petroleum and Chemical Corporation Beijing 100728

The Cenozoic rift basins in eastern China show a clear temporal and spatial zonation and episodic tectonic evolution, which control their episodic hydrocarbon generation and zonal accumulation. In this paper, based on the study of depositional architecture, hydrocarbon migration system and dynamic evolution in the rift basins, combinations of hydrocarbon accumulation elements were analyzed using sequence stratigraphy. Hydrocarbon distribution in system tracts with different sequence orders was further studied. And we summarized stacking patterns and horizontal combination relationships for different types of reservoirs, such as lithological, tectonic-lithological, tectonic and stratigraphical reservoirs which can be observed from depression center to basin margin. The result reveals that various scales of pools exhibit significant distribution and evolution orderliness in different pool-forming units, i.e., depositional systems, plays and depressions. The regular distribution of various scales of pools is closely related to tectonic evolution and depositional filling in the rift basins. The result can be applied to the fine petroleum exploration in rift basins in eastern China. It will promote the scientific prediction and evaluation of reservoir types and their spatial distribution, lead to the active shifts of exploration targets in different zones, and thus support the stable progress of fine exploration in mature exploration areas.

关键词： rift basin pathway system reservoir-forming element distribution regularity of hydrocarbon accumulation Cenozoic

Asymptotic stability of port-hamiltonian systems with constant inputs

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Control Theory and Technology 2021年第2期19卷 227-235页

作者： Liangcheng cai School of Electric Engineer Southwest Jiaotong UniversityChengduSichuan610031China

In this paper, the asymptotic stability of Port-Hamiltonian (PH) systems with constant inputs is studied. Constant inputs are useful for stabilizing systems at their nonzero equilibria and can be realized by step signals. To achieve this goal, two methods based on integral action and comparison principle are presented in this paper. These methods change the convex Hamiltonian function and the restricted damping matrix of the previous results into a Hamiltonian function with a local minimum and a positive semidefinite matrix, respectively. Due to common conditions of Hamiltonian function and damping matrix, the proposed method asymptotically stabilizes more classes of PH systems with constant inputs than the existing methods. Finally, the validity and advantages of the presented methods are shown in an example.

关键词： Port-Hamiltonian systems Constant inputs Integral action Compare principle Asymptotic stability

Teaching mechanism empowered by virtual simulation: Edge computing–driven approach

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Digital Communications and Networks 2023年第2期9卷 483-491页

作者： Ziqiao Wang Xiaomu cai Yanbian University Yanji133000China

With the rapid development of network and communication techniques,the teaching forms have become *** enhance the education experience and improve the teaching environment,an increasing number of educational institutions have adopted virtual simulation technology.A typical teaching mechanism is to exploit Virtual Reality(VR)technology,which affords participants an immersive ***,such a VRbased mode is highly ***,the performance of this technology requires further *** one hand,for VR 360video,the current intraframe decision cannot adapt to rapid response *** the other hand,the generated data size is considerably large and fast computation may not be realized,depending on the local VR ***,this study proposes an improved teaching mechanism empowered by edge computing–driven VR,called VE4T,that involves two ***,an intraframe decision algorithm for VR 360videos is devised to realize the rapid ***,an edge computing framework is proposed to offload some tasks to an edge server for computation,where a task scheduling strategy is developed to check whether a task needs to be ***,experiments are performed using a practical teaching scenario with some VR *** obtained results demonstrate that VE4T is more efficient than existing mechanisms.

关键词： Virtual reality Edge computing Immersive experience Scheduling strategy Intraframe decision

The [4+2] Cycloaddition of 2-Pyrone in Total Synthesis

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Chinese Journal of Chemistry 2019年第9期37卷 946-976页

作者： Quan cai Department of Chemistry and Research Center for Molecular Recognition and Synthesis Fudan University220 Handan Rd.Shanghai 200433China

Diels-Alder reaction is one of the most important reactions in organic synthesis and has witnessed great achievements in total syntheses of complex natural *** this review,we will focus on the [4+2] cycloaddition that utilizes 2-pyrone as the diene *** advances of its applications in the total syntheses of natural products in the past fifty years will be discussed here.

关键词： Cycloaddition 2-Pyrone Total Synthesis

A Remark on Chen’s Theorem (Ⅱ)

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Chinese Annals of Mathematics,Series B 2008年第6期29卷 687-698页

作者： Yingchun cai Department of Mathematics Tongji University Shanghai 200092 China

Let p denote a prime and P2 denote an almost prime with at most two prime factors. The author proves that for sufficiently large x,∑p≤x p＋2=P2 1〉1.13Cx/log^2x,where the constant 1.13 constitutes an improvement of ... 详细信息

关键词： Chen's theorem Sieve Mean value theorem

Evaluation of the ecological status with benthic indices in the coastal system： the case of Bohai Bay （China）

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Frontiers of Environmental Science & Engineering 2014年第5期8卷 737-746页

作者： Wenqian cai State Environmental Protection Key Laboratory of Estuary and Coastal Environment Chinese Research Academy of Environmental Sciences Beijing 100012 China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental Sciences Beijing 100012 China

Based on biologic and environmental materials collected from coastal areas of Bohai Bay （China） in April, 2008, three biotic indices （AZTI＇s Marine Biotic Index （AMBI）, Shannon-Wiener Index and W-statistic） were applied together to evaluate the ecological status of the sampling area. The results showed a clear spatial gradient from a worse ecological status in the near-shore areas （especially around Haihe and Jiyun River Estuaries） to a better status in the offshore areas. While all the three indices could assist decision makers in visualizing spatial changes of organic pollutants in Bohai Bay, two indices, i. e., AMBI and Shannon-Wiener index, were effective in distinguishing sites from Haihe River Estuary, Jiyun River Estuary and other area. However, W-statistic can＇t tell the differences between estuaries and other area. It would be explained that organic pollutants and/or other environ- mental stresses in Bohai Bay were not strong enough to reduce the size ofmacrozoobenthos, which may cause both of the abundance and biomass curves crossed. To our knowledge, this is the first time that several benthic indices were used to assess the benthic ecological status in Bohai Bay, which gave the similar results. Furthermore, there is indication that the ecological status is related to excess input of wastewater along main rivers and outlets. In a word, AMBI, Shannon-Wiener Index and W-statistic could be able to assess the benthic ecological status of Bohai Bay under the organic pollutants pressure.

关键词： AZTI's Marine Biotic Index Shannon-Wiener Index W-statistic ecological status coastal system,Bohai Bay (China)

MULTIPLE PARAMETERS IDENTIFICATION PROBLEMS IN RESISTIVITY WELL-LOGGING

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Chinese Annals of Mathematics,Series B 1998年第3期19卷 265-272页

作者： cai ZHIJIE Department of Mathematics Fudan University Shanghai 200433 China

In petroleum exploitation, the main aim of resistivity well-logging is to determine the resistivity of the layers by measuring the potential on the electrodes. This mathematical problem can be described as an inverse problem for the elliptic equivalued surface boundary value problem. In this paper, the author gets the expression of the derivative functions of the potential on the electrodes with respect to the resistivity of the layers. This allows us to solve the identification problem of the resistivity of the layers.

关键词： Multiple parameters identification problem Resistivity well-logging Inverse problem Equivalued surface boundary value problem