作者：
Du, Dan*;Gong, Xueyu;Wang, Zhenhua;Yu, Jun;Zheng, Pingwei
期刊：
Journal of Plasma Physics,2012年78(6):595-599 ISSN：0022-3778
通讯作者：
Du, Dan
作者机构：
[Du, Dan; Yu, Jun] Univ S China, Dept Math & Phys, Hengyang City, Hunan, Peoples R China.;[Wang, Zhenhua; Gong, Xueyu] Univ S China, Dept Nucl Sci & Technol, Hengyang City, Hunan, Peoples R China.;[Zheng, Pingwei] Univ S China, Dept Environm Protect & Safety Engn, Hengyang City, Hunan, Peoples R China.
通讯机构：
[Du, Dan] U;Univ S China, Dept Math & Phys, Hengyang City, Hunan, Peoples R China.
摘要：
A well-optimized design of an ion cyclotron resonance heating (ICRH) antenna is very important for steady-state plasma heating with high radio frequency (RF) power of several tens of megawatts. However, a sharp decrease in the coupling RF power because of impedance mismatch of ICRH system is an issue that must be resolved for present-day fusion reactors and International Thermonuclear Experimental Reactor. This paper has theoretically analyzed the ICRH antenna's impedance matching for ELMy plasmas on experimental advanced superconducting tokamak (EAST) by the transmission line theory. The results indicate that judicious choice of the optimal feeder location is found useful for adjustable capacitors' tolerance to the variations of the antenna input impedance during edge-localized mode (ELM) discharge, which is expected to be good for the design of ICRH antenna system and for real-time feedback control during ELM discharge on EAST.
作者机构：
[Ning, Yan-Tao; Peng, Zhi-Hua; Guo, Yan-Chun; Gong, Xue-Yu; Peng, Yan-Feng] Univ S China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Peng, Zhi-Hua] U;Univ S China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
carbon nanotubes;hydrogen plasma;static magnetic field;microwave absorption
摘要：
We theoretically investigate the microwave absorption properties of hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes under an external static magnetic field in the frequency range 0.3 GHz to 30 GHz, using the Maxwell equations in conjunction with a general expression for the effective complex permittivity of magnetized plasma known as the Appleton-Hartree formula. The effects of the external static magnetic field intensity and the incident microwave propagation direction on the microwave absorption of hydrogen plasma in CNTs are studied in detail. The numerical results indicate that the microwave absorption properties of hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes can be obviously improved when the exter- nal static magnetic field is applied to the material. It is found that the specified frequency microwave can be strongly absorbed by the hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes over a wide range of incidence angles by adjusting the external magnetic field intensity and the parameters of the hydrogen plasma.
关键词：
A multiple-level food chain model;Food chain length;Index theory in cone;Stability
摘要：
In this paper, we construct a ecological system with prey-taxis. From the dynamic point of view we analytically and numerically investigate the steady states. Our results show how the combined action of the death rates, chemotaxis, diffusivity and conversion efficiency to influence the survival ability of multiple consumer levels in a ecological system with self-produced nutriment. Furthermore, the food chain length of our model can be determined by the co-existence conditions of all consumer levels. Numerical simulation corroborates the analytical results.
摘要：
Guiding center equations of particle motion under a toroidal magnetic configuration were derived using a new defined magnetic flux coordinates system. A transformation method to Hamiltonian canonical variables is presented in this work. It was found that the newly defined flux coordinates are simple self-consistent, and could be applied to any magnetostatic equilibrium with a nested flux configuration.
作者机构：
[Zhu, Huiyan] Univ S China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.;[Ou, Chunhua] Mem Univ Newfoundland, Dept Math & Stat, St John, NF A1C 5S7, Canada.
通讯机构：
[Ou, Chunhua] M;Mem Univ Newfoundland, Dept Math & Stat, St John, NF A1C 5S7, Canada.
作者机构：
[张楚汉; 郭长青] State Key Laboratory of Hydroscience and Hydraulic Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China;[郭长青] School of Mathematics and Physics, University of South China, Hengyang 421001, China
通讯机构：
State Key Laboratory of Hydroscience and Hydraulic Engineering, Department of Hydraulic Engineering, Tsinghua University, China
摘要：
An analytic solution for the problem of Williams–Brinkmann axisymmetric steady flow in the vicinity of a stagnation point at a blunt body is proposed. The boundary conditions are embedded in the main system of equations by means of the Boubaker polynomials expansion scheme (BPES). These differential equations are solved analytically and yield continuous and differentiable solutions compared to some published ones. KeywordsWilliams–Brinkmann flow–stagnation point–Boubaker polynomials expansion scheme (BPES)–boundary conditions–non-Newtonian fluid–fluid hydrodynamics
摘要：
Based on the ideal solution approximation, the model for size-dependent melting temperature of pure metal nanoparticles is extended to binary alloy systems. The developed model, free of any adjustable parameter, demonstrates that the melting temperature is related to the size and composition of alloy nanoparticles. The melting temperature of CuNi, PbBi and SnIn binary alloy nanocrystals is found to be consistent with the experiments and molecular dynamics simulations. The research reveals that alloy nanocrystals have similar melting nature as pure metal.
作者机构：
[Lizhong Jiang; Zhiping Zeng; Weiguo Long; Lingkun Chen] School of Civil Engineering, Central South University, Changsha, Hunan-410075, China;[Weiguo Long] School of Mathematics and Physics, University of South China, Hengyang, Hunan-421001, China;[Lizhong Jiang; Zhiping Zeng; Weiguo Long; Lingkun Chen] National Engineering Laboratory for High Speed Railway Construction, Central South University, Changsha, Hunan-410075, China
通讯机构：
School of Civil Engineering, Central South University, China
摘要：
In this paper, the responses of high-speed railway bridge subjected to seismic load were investigated by numerical simulation. Elastic deformation will occur in the bridge system under low-level earthquake; however, the bridge system may enter a nonlinear stage under high-level earthquake. The whole finite element model of the bridge system was set up by means of ANSYS software and self-compiled moment-curvature relationship program, the elastic seismic responses of bridge system and the elastic-plastic deformation of piers considering different vehicle speeds are calculated respectively. The calculation results show that, the earthquake responses of bridge system are increase in general with the increase of vehicle speed and earthquake intensity, and the bottom of piers step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred at the pier bottom, the pier bottom step into the plastic stage, some measures such as lateral reinforced steel encryption should be taken into account to ensure safety.
摘要：
In this paper, we propose a theoretical scheme of many-ghost imaging in terms of Nth-order correlated thermal light. We obtain the Gaussian thin lens equations in the many-ghost imaging protocol. We show that it is possible to produce N−1 ghost images of an object at different places in a nonlocal fashion by means of a higher order correlated imaging process with an Nth-order correlated thermal source and correlation measurements. We investigate the visibility of the ghost images in the scheme and obtain the upper bounds of the visibility for the Nth-order correlated thermal-light ghost imaging. It is found that the visibility of the ghost images can be dramatically enhanced when the order of correlation becomes larger. It is pointed out that the many-ghost imaging phenomenon is an observable physical effect induced by higher order coherence or higher order correlations of optical fields.
作者机构：
[谭琼华; 刘伟俊; 王华国] School of Mathematical Science and Computing Technology, Central South Univ, Changsha, Hunan 410075, China;[谭琼华] School of Mathematics and Physics, Univ of South China, Hengyang, Hunan 421001, China
通讯机构：
School of Mathematical Science and Computing Technology, Central South Univ, China
摘要：
In this paper, a two-species Lotka-Volterra predator-prey model with two delays is considered. By analyzing the associated characteristic transcendental equation, the linear stability of the positive equilibrium is investigated and Hopf bifurcation is demonstrated. Some explicit formulae for determining the stability and direction of Hopf bifurcation periodic solutions bifurcating from Hopf bifurcations are obtained by using normal form theory and center manifold theory. Some numerical simulations for supporting the theoretical results are also included.
