A new class of fixed-time bipartite flocking protocols for multi-agent systems
作者：
Liu, Hongliang* ;Wang, Xiao;Huang, Yao;Liu, Yicheng
期刊：
Applied Mathematical Modelling ,2020年84:501-521 ISSN：0307-904X
通讯作者：
Liu, Hongliang
作者机构：
[Liu, Hongliang] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Liu, Yicheng; Liu, Hongliang; Huang, Yao; Wang, Xiao] Natl Univ Def Technol, Dept Math, Changsha 410073, Peoples R China.
通讯机构：
[Liu, Hongliang] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Collision avoidance;Diameter of cluster;Fixed-time bipartite flocking;Multi-agent systems
摘要：
This work is concerned with the fixed-time stability theorem and the fixed-time bipartite flocking with collision avoidance for multi-agent systems. Under the framework of Filippov solution, a new theorem of fixed-time stability is established and a high-precision estimation of settling time is given. As an important application, the fixed-time bipartite flocking protocol of nonlinear multi-agent systems is proposed. Employing this fixed-time stability theorem and the structurally balanced signed graph theorem, the bipartite flocking without collision is achieved within a fixed-time. Moreover, the convergent time of the bipartite flocking is merely depending on the parameters of the protocol and the network connectivity. In addition, the upper bound of the size for each disjoint cluster can be estimated by the parameters of the protocol, the network connectivity and the initial states of the system. These results are novel, which are illustrated by both theoretical analysis and numerical simulations. © 2020 Elsevier Inc.
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On Collision Avoiding Fixed-Time Flocking with Measurable Diameter to a Cucker-Smale-Type Self-Propelled Particle Model
作者：
Xiao, Qizhen;Liu, Hongliang* ;Xu, Zhenghua* ;Ouyang, Zigen
期刊：
Complexity ,2020年2020(2020):1094950:1-1094950:12 ISSN：1076-2787
通讯作者：
Liu, Hongliang;Xu, Zhenghua
作者机构：
[Xiao, Qizhen; Liu, HL; Xu, Zhenghua; Liu, Hongliang; Ouyang, Zigen] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Liu, HL; Xu, ZH] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
摘要：
Dealing with the fixed-time flocking issue is one of the most challenging problems for a Cucker-Smale-type self-propelled particle model. In this article, the fixed-time flocking is established by employing a fixed-time stability theorem when the communication weight function has a positive infimum. Compared with the initial condition-based finite-time stability, an upper bound of the settling time in this paper is merely dependent on the design parameters. Moreover, the size of the final flocking can be estimated by the number of particles and the initial states of the system. In addition, a sufficient condition is formulated to guarantee that all particles do not collide during the process of the flocking. These results can give a reasonable explanation to some flocking phenomena such as bird flocks, fish schools, or human group behaviors. Finally, three numerical examples are granted to display the performance of the obtained results. © 2020 Qizhen Xiao et al.
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英文
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Several new infinite families of bent functions via second order derivatives
作者：
Zheng, Lijing;Peng, Jie* ;Kan, Haibin;Li, Yanjun
期刊：
Cryptography and Communications ,2020年12(6):1143-1160 ISSN：1936-2447
通讯作者：
Peng, Jie
作者机构：
[Zheng, Lijing; Kan, Haibin] Fudan Univ, Sch Comp Sci, Shanghai 200433, Peoples R China.;[Zheng, Lijing] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.;[Peng, Jie; Li, Yanjun] Shanghai Normal Univ, Math & Sci Coll, Guilin Rd 100, Shanghai 200234, Peoples R China.
通讯机构：
[Peng, Jie] S;Shanghai Normal Univ, Math & Sci Coll, Guilin Rd 100, Shanghai 200234, Peoples R China.
关键词：
Bent functions;Second order derivative;Algebraic degree;Dual;Walsh spectrum
摘要：
Inspired by a recent work of Tang et al. on constructing bent functions [14, IEEE TIT, 63(1): 6149-6157, 2017], we introduce a property (Pτ) of any Boolean function that its second order derivatives vanish at any direction (ui,uj) for some τ-subset {u1,…,uτ} of F2n, and then establish a link between this property and the construction of Tang et al. (IEEE Trans. Inf. Theory 63(10), 6149–6157 2017). It enables us to find more bent functions efficiently. We construct (at least) five new infinite families of bent functions from some known functions: the Gold’s bent functions and some quadratic non-monomial bent functions, Leander’s monomial bent functions, Canteaut-Charpin-Kyureghyan’s monomial bent functions, and the Maiorana-McFarland class of bent functions, respectively. Our result generalizes some recent works on bent functions. We also provide the corresponding dual functions in all our constructions except the quadratic non-monomial one. It also turns out that we can get new bent functions outside the Maiorana-McFarland completed class. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.
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英文
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A note on the fixed-time bipartite flocking for nonlinear multi-agent systems
作者：
Xiao, Qizhen;Liu, Hongliang* ;Wang, Xiao;Huang, Yao
期刊：
Applied Mathematics Letters ,2020年99:105973 ISSN：0893-9659
通讯作者：
Liu, Hongliang
作者机构：
[Xiao, Qizhen; Liu, Hongliang] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Huang, Yao; Wang, Xiao] Natl Univ Def Technol, Dept Math, Changsha 410073, Hunan, Peoples R China.
通讯机构：
[Liu, Hongliang] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Fixed-time bipartite flocking;Multi-agent systems;Structurally balanced graph diameter of clusters
摘要：
This work focuses on the fixed-time bipartite flocking control problem for multi-agent systems. By employing the structurally balanced signed graph theory and a fixed-time stability theorem, we can prove that all individuals can be partitioned into two disjoint clusters within a fixed time and they move to opposite directions with the same velocity. We find that the settling time merely depends on the parameters and network connectivity. Moreover, the parameters, network connectivity and the initial states have an important influence on the diameter of each disjoint cluster. The results are novel, which are firstly illustrated by both theoretical analysis and numerical simulations. (C) 2019 Elsevier Ltd. All rights reserved.
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英文
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Thermal Rectification in Asymmetric Graphene/Hexagonal Boron Nitride van der Waals Heterostructures
作者：
Chen, Xue-Kun* ;Pang, Min;Chen, Tong;Du, Dan* ;Chen, Ke-Qiu*
期刊：
ACS Applied Materials & Interfaces ,2020年12(13):15517-15526 ISSN：1944-8244
通讯作者：
Chen, Xue-Kun;Du, Dan;Chen, Ke-Qiu
作者机构：
[Chen, Xue-Kun; Du, D; Pang, Min; Du, Dan] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Chen, Ke-Qiu] Hunan Univ, Sch Phys & Elect, Dept Appl Phys, Changsha 410082, Hunan, Peoples R China.;[Chen, Tong] Jiangxi Univ Sci & Technol, Sch Energy & Mech Engn, Nanchang 330013, Jiangxi, Peoples R China.
通讯机构：
[Chen, XK; Du, D] U;[Chen, Ke-Qiu] H;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;Hunan Univ, Sch Phys & Elect, Dept Appl Phys, Changsha 410082, Hunan, Peoples R China.
关键词：
thermal rectification;vdW heterostructure;asymmetry;phonon mismatch;molecular dynamics
摘要：
Graphene/hexagonal boron nitride (h-BN) heterostructures assembled by van der Waals (vdW) interactions show numerous unique physical properties such as quantum Hall effects and exotic correlated states, which have promising potential applications in the design of novel electronic devices. Understanding thermal transport in such junctions is critical to control the performance and stability of prospective nanodevices. In this work, using nonequilibrium molecular dynamics simulations, we systematically investigate the thermal transport in asymmetric graphene/h-BN vdW heterostructures. It is found that the heat prefers to flow from the monolayer to the multilayer regions, resulting in a significant thermal rectification (TR) effect. To determine the optimum conditions for TR, the influences of sample length, defect density, asymmetric degree, ambient temperature, and vdW interaction strength are studied. Particularly, we found that the TR ratio could be improved by about 1 order of magnitude via increasing the coupling strength from 1 to 10, which clearly distinguishes from the commonly held notion that the TR ratio is practically insensitive or even decreasing with the interaction strength. Detailed spectral analysis reveals that this unexpected increase of the TR ratio can be attributed to heavily modified phonon properties of encased graphene due to enhanced interlayer coupling. Our results elucidate the importance of vdW interactions to heat conduction in nanostructures. Copyright © 2020 American Chemical Society.
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英文
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New convergence results on cellular neural networks with leakage delay and proportional delay
作者：
Xu, Changjin* ;Liao, Maoxin;Li, Peiluan
期刊：
AIP Advances ,2020年10(7):075022 ISSN：2158-3226
通讯作者：
Xu, Changjin
作者机构：
[Xu, Changjin] Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Peoples R China.;[Liao, Maoxin] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Li, Peiluan] Henan Univ Sci & Technol, Sch Math & Stat, Luoyang 471023, Peoples R China.
通讯机构：
[Xu, Changjin] G;Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Peoples R China.
摘要：
In the present work, we mainly focus on shunting inhibitory cellular neural networks (SICNNs) involving leakage delays and proportional delays. By applying the inequality technique, a novel sufficient criterion to ascertain the convergence of every solution of SICNNs with leakage delays and proportional delays is derived. Simulation results are delineated to substantiate the correctness of our theoretical findings. Up to now, very few scholars deal with the neural networks with leakage delays and proportional delays. The derived conclusion of this work is a novelty and supplements several earlier works.
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英文
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Modulation of thermal transport in AlxGa1-xAs alloy nanowires with varying compositions
作者：
Xie, Zhong-Xiang* ;Yu, Xia;Chen, Xue-Kun;Zhou, Wu-Xing;Shi, Yi-Min;...
期刊：
Applied Physics Letters ,2020年116(14):143102 ISSN：0003-6951
通讯作者：
Xie, Zhong-Xiang;Zhang, Li-Fu
作者机构：
[Xie, Zhong-Xiang; Shi, Yi-Min; Yu, Xia] Hunan Inst Technol, Dept Math & Phys, Hengyang 421002, Peoples R China.;[Chen, Xue-Kun] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Zhou, Wu-Xing] Hunan Univ Sci & Technol, Sch Mat Sci & Engn, Xiangtan 411201, Peoples R China.;[Zhang, Li-Fu] Shenzhen Univ, Inst Microscale Optoelect, Shenzhen 518060, Peoples R China.
通讯机构：
[Xie, Zhong-Xiang] H;[Zhang, Li-Fu] S;Hunan Inst Technol, Dept Math & Phys, Hengyang 421002, Peoples R China.;Shenzhen Univ, Inst Microscale Optoelect, Shenzhen 518060, Peoples R China.
摘要：
Phonon dispersion relations and thermal conductance in AlxGa1-xAs alloy nanowires with varying compositions are investigated. When x varies from 0 to 1, the lowest-energy mode remains almost unchanged, while the cutoff frequency of the high-order modes increases. The thermal conductance of AlxGa1-xAs alloy nanowires is inversely proportional to the Al content x, but proportional to the nanowire width. For a two-terminal GaAs/AlxGa1-xAs/AlAs transport system, it is found that the thermal conductance first decreases and then increases as x increases from 0 to 1. The minimum thermal conductance at the critical x = 0.66 can be observed independent of the nanowire width. A concise analysis of these results is made. © 2020 Author(s).
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英文
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PD9 Control Strategy for a Fractional-Order Chaotic Financial Model
作者：
Xu, Changjin* ;Liao, Maoxin;Li, Peiluan;Xiao, Qimei;Yuan, Shuai
期刊：
Complexity ,2019年2019:2989204:1-2989204:14 ISSN：1076-2787
通讯作者：
Xu, Changjin
作者机构：
[Xu, Changjin] Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Guizhou, Peoples R China.;[Liao, Maoxin] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Li, Peiluan] Henan Univ Sci & Technol, Sch Math & Stat, Luoyang 471023, Peoples R China.;[Xiao, Qimei] Changsha Univ Sci & Technol, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Hunan, Peoples R China.;[Yuan, Shuai] Cent S Univ, Sch Math & Stat, Changsha 410083, Hunan, Peoples R China.
通讯机构：
[Xu, Changjin] G;Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Guizhou, Peoples R China.
摘要：
In this article, based on the previous works, a new fractional-order financial model is put up. The chaotic behavior of the fractional-order financial model is suppressed by designing an appropriate PD9 controller. By choosing the delay as the bifurcation parameter, we establish the sufficient condition to guarantee the stability and the existence of Hopf bifurcation of fractional-order financial model. Also, the influence of the delay and the fractional order on the stability and the existence of Hopf bifurcation of fractional-order financial model is revealed. An example is given to confirm the effectiveness of the analysis results. The main findings of this article play an important role in maintaining economic stability. © 2019 Changjin Xu et al.
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英文
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Control Scheme for a Fractional-Order Chaotic Genesio-Tesi Model
作者：
Xu, Changjin* ;Li, Peiluan;Liao, Maoxin;Liu, Zixin;Xiao, Qimei;...
期刊：
Complexity ,2019年2019:4678394:1-4678394:15 ISSN：1076-2787
通讯作者：
Xu, Changjin
作者机构：
[Xu, Changjin] Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Guizhou, Peoples R China.;[Li, Peiluan] Henan Univ Sci & Technol, Sch Math & Stat, Luoyang 471023, Peoples R China.;[Liao, Maoxin] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Liu, Zixin] Guizhou Univ Finance & Econ, Sch Math & Stat, Guiyang 550004, Guizhou, Peoples R China.;[Xiao, Qimei] Changsha Univ Sci & Technol, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Hunan, Peoples R China.
通讯机构：
[Xu, Changjin] G;Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Guizhou, Peoples R China.
摘要：
In this paper, based on the earlier research, a new fractional-order chaotic Genesio-Tesi model is established. The chaotic phenomenon of the fractional-order chaotic Genesio-Tesi model is controlled by designing two suitable time-delayed feedback controllers. With the aid of Laplace transform, we obtain the characteristic equation of the controlled chaotic Genesio-Tesi model. Then by regarding the time delay as the bifurcation parameter and analyzing the characteristic equation, some new sufficient criteria to guarantee the stability and the existence of Hopf bifurcation for the controlled fractional-order chaotic Genesio-Tesi model are derived. The research shows that when time delay remains in some interval, the equilibrium point of the controlled chaotic Genesio-Tesi model is stable and a Hopf bifurcation will happen when the time delay crosses a critical value. The effect of the time delay on the stability and the existence of Hopf bifurcation for the controlled fractional-order chaotic Genesio-Tesi model is shown. At last, computer simulations check the rationalization of the obtained theoretical prediction. The derived key results in this paper play an important role in controlling the chaotic behavior of many other differential chaotic systems. © 2019 Changjin Xu et al.
语种：
英文
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On non-collision flocking and line-shaped spatial configuration for a modified singular Cucker–Smale model
作者：
Liu, Hongliang* ;Wang, Xiao;Liu, Yicheng;Li, Xiang
期刊：
Communications in Nonlinear Science and Numerical Simulation ,2019年75(Aug.):280-301 ISSN：1007-5704
通讯作者：
Liu, Hongliang
作者机构：
[Liu, Yicheng; Liu, Hongliang; Li, Xiang; Wang, Xiao] Natl Univ Def Technol, Dept Math, Changsha 410073, Hunan, Peoples R China.;[Liu, Hongliang] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Liu, Hongliang] N;Natl Univ Def Technol, Dept Math, Changsha 410073, Hunan, Peoples R China.
关键词：
Cucker-Smale system;Singular communication weight;Collision avoiding flocking;Line-shape spatial configuration
摘要：
This paper is concerned with a singular Cucker–Smale model with a general targeted pattern driving force, which ensures that the particles finally come to the desired spatial configuration. Under some suitable conditions, we prove that the exponent α ≥ 1 in the communication weight leads to global regularity of solutions so that the system has an asymptotic flocking without collision between any agent. As an example, a prescribed driving force is given to demonstrate that the particles finally come to a line-shaped formation with collision avoidance, which can be viewed as a reasonable explanation for the wild geese flying in a line-shape in the sky. Moreover, this mechanism can be applied to the UAVs forming a line-shape to complete some special military missions. These results are novel, which are illustrated by both theoretical analysis and numerical simulations. © 2019
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英文
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Spectral link and macroscopic non-universality in turbulent plane Couette flow
作者：
Zhang, Dongrong*
期刊：
Fluid Dynamics Research ,2019年51(5):055504 ISSN：0169-5983
通讯作者：
Zhang, Dongrong
作者机构：
[Zhang, Dongrong] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Zhang, Dongrong] Okinawa Inst Sci & Technol Grad Univ, Onna, Okinawa 9040495, Japan.
通讯机构：
[Zhang, Dongrong] U;[Zhang, Dongrong] O;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;Okinawa Inst Sci & Technol Grad Univ, Onna, Okinawa 9040495, Japan.
关键词：
Friction factor;Macroscopic non-universality;Mean-velocity profile;Spectral link;Turbulent plane Couette flow
摘要：
In fully developed turbulent plane Couette flow the classical experimental data of frictional factor f versus Reynolds number Re display well-known disparities which have long remained unexplained. These disparities are accompanied by previously unnoticed disparities in the wakes, and only in the wakes, of the attendant mean-velocity profiles (MVPs). To help explain these experimental data, we apply the model of the 'spectral link' for MVPs to turbulent plane Couette flows. The model links the dissipative range, the inertial range, and the energetic range of the standard phenomenological model of the spectrum of turbulent kinetic energy to, respectively, the buffer layer, the log layer, and the wake of the MVPs. By assessing the empirical data using the spectral model, we argue for the existence, in plane Couette flow, of multiple states of turbulence which differ from one another only at the largest lengthscales in the flow, corresponding to the energetic range, where the spectrum is subject to finite-domain effects. Thus, the multiplicity of turbulent states is entirely consistent with small-scale universality, and the experimental data on plane Couette flow pose no challenge to the phenomenological theory of turbulence. Our findings might apply more broadly to a general class of flows engendered by moving boundaries. © 2019 The Japan Society of Fluid Mechanics and IOP Publishing Ltd.
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英文
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Dynamics of an ultrasound contrast agent microbubble near spherical boundary in ultrasound field
作者：
Hu, Ji-Wen;Wang, Lian-Mei;Qian, Sheng-You* ;Liu, Wen-Yi;Liu, Ya-Tao;...
期刊：
中国物理B ,2019年28(11):204-209 ISSN：1674-1056
通讯作者：
Qian, Sheng-You
作者机构：
[Liu, Wen-Yi; Lei, Wei-Rui; Wang, Lian-Mei; Liu, Ya-Tao; Hu, Ji-Wen] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Qian, Sheng-You; Hu, Ji-Wen] Hunan Normal Univ, Sch Phys & Elect, Changsha 410081, Hunan, Peoples R China.
通讯机构：
[Qian, Sheng-You] H;Hunan Normal Univ, Sch Phys & Elect, Changsha 410081, Hunan, Peoples R China.
关键词：
ultrasound contrast agent (UCA) microbubble;spherical boundary;ultrasound;natural frequency
摘要：
The goal of this article is to establish the conditions of excitation where one has to deal with ultrasound contrast agent (UCA) microbubbles pulsating near biological tissues with spherical boundary in ultrasound field for targeted drug delivery and cavitation-enhanced thrombolysis, etc., and contributes to understanding of mechanisms at play in such an interaction. A modified model is presented for describing microbubble dynamics near a spherical boundary (including convex boundary and concave boundary) with an arbitrary-sized aperture angle. The novelty of the model is such that an oscillating microbubble is influenced by an additional pressure produced by the sound reflection from the boundary wall. It is found that the amplitude of microbubble oscillation is positively correlated to the curve radius of the wall and negatively correlated to the aperture angle of the wall and the sound reflection coefficient. Moreover, the natural frequency of the microbubble oscillation for such a compliable wall increases with the wall compliance, but decreases with the reduction of the wall size, indicating distinct increase of the natural frequency compared to a common rigid wall. The proposed model may allow obtaining accurate information on the radiation force and signals that may be used to advantage in related as drug delivery and contrast agent imaging. © 2019 Chinese Physical Society and IOP Publishing Ltd.
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英文
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Distribution of radon and risk assessment of its radiation dose in groundwater drinking for village people nearby the W-polymetallic metallogenic district at Dongpo in southern Hunan province, China
作者：
Tan, Wanyu;Li, Yongmei;Tan, Kaixuan* ;Xie, Yanshi;Han, Shili;...
期刊：
Applied Radiation and Isotopes ,2019年151:39-45 ISSN：0969-8043
通讯作者：
Tan, Kaixuan
作者机构：
[Li, Yongmei; Wang, Peng; Tan, Wanyu; Xie, Yanshi; Tan, Kaixuan; Han, Shili] Univ South China, Sch Resources Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.;[Tan, Kaixuan] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Tan, Kaixuan] U;Univ South China, Sch Resources Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.
关键词：
Annual effective dose;Groundwater;Ingestion;Inhalation;Radon concentration
摘要：
Radon in the household water (especially groundwater) which is an important source of indoor radon, has become a potential health hazard to residents. In this study, radon concentrations in groundwater sampled from five villages near Dongpo W-polymetallic metallogenic region were measured using RAD-7 detector with RAD H2O accessory, and the effect of regional geology and mineralization on radon concentration in groundwater was studied. In addition, we also estimated the radiation doses received by people via ingestion of radon in water and inhalation of the radon from the indoor air while using water. The results show that the radon concentration in groundwater samples varies from 1.29 Bq L(-1) to 31.31 Bq L(-1) with 10.47 Bq L(-1) on average, and about 31.3% of the groundwater samples analyzed have a higher radon concentration than the maximum contaminant level of 11.1 Bq L(-1) recommended by United States Environmental Protection Agency (USEPA). The relatively high radon level in groundwater can be attributed to a relatively high uranium background produced by the magmatic activity and magmatic-hydrothermal system. The values of annual effective dose (AEDing) due to ingestion of radon in groundwater range from 0.002mSv y(-1) to 0.055mSv y(-1), 0.005mSv y(-1) to 0.11mSv y(-1) and 0.008mSv y(-1) to 0.188mSv y(-1) for adult, child and infant respectively. The values of annual effective dose due to the inhalation of radon released from water are 63.6, 15.4 and 3.8 times of those through the ingestion of radon in groundwater by the adults, children and infants, respectively. In addition, the values of estimated total annual effective doses are 0.020-0.480mSv y(-1), 0.017-0.406mSv y(-1) and 0.020-0.484mSv y(-1) for adult, child and infant, respectively. These values are much lower than the reference dose level of 1mSv y(-1) recommended by World Health Organization (WHO) and United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR).
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英文
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Effects of resonant magnetic perturbation on the instability of single tearing mode with non-shear flow
作者：
Wang, Le;Yang, Ming;Lin, Wen-Bin*
期刊：
中国物理B ,2019年28(1):466-469 ISSN：1674-1056
通讯作者：
Lin, Wen-Bin
作者机构：
[Wang, Le; Lin, Wen-Bin; Yang, Ming] Southwest Jiaotong Univ, Sch Phys Sci & Technol, Chengdu 610031, Sichuan, Peoples R China.;[Lin, Wen-Bin] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Lin, Wen-Bin] S;[Lin, Wen-Bin] U;Southwest Jiaotong Univ, Sch Phys Sci & Technol, Chengdu 610031, Sichuan, Peoples R China.;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
resonant magnetic perturbation;tearing mode;instability;flow
摘要：
Non-shear flow can change the O-point position of a magnetic island, and thus it may play an important role in the effects of resonant magnetic perturbation (RMP) on the single tearing mode. We employ the nonlinear magnetohydrodynamics model in a slab geometry to investigate how RMP affects the single tearing mode instability with non-shear flow. It is found that the driving and suppressing effects of RMP on single tearing mode instability will appear alternately. When the flow velocity is small, the suppressing effect plays a major role through the development of the mode, and the tearing mode instability will be suppressed. With the flow velocity increasing, the driving effect will increase, while the suppressing effect will decrease. When the two effects reach equilibrium, the tearing mode will become stable. © 2019 Chinese Physical Society and IOP Publishing Ltd.
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Influence of multiple time delays on bifurcation of fractional-order neural networks
作者：
Xu, Changjin* ;Liao, Maoxin;Li, Peiluan;Guo, Ying;Xiao, Qimei;...
期刊：
Applied Mathematics and Computation ,2019年361:565-582 ISSN：0096-3003
通讯作者：
Xu, Changjin
作者机构：
[Xu, Changjin] Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Guizhou, Peoples R China.;[Liao, Maoxin] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Li, Peiluan] Henan Univ Sci & Technol, Sch Math & Stat, Luoyang 471023, Peoples R China.;[Guo, Ying] Cent S Univ, Sch Informat Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Xiao, Qimei] Changsha Univ Sci & Technol, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Hunan, Peoples R China.
通讯机构：
[Xu, Changjin] G;Guizhou Univ Finance & Econ, Guizhou Key Lab Econ Syst Simulat, Guiyang 550004, Guizhou, Peoples R China.
关键词：
Neural networks;Hopf bifurcation;Stability;Fractional order;Delay
摘要：
In this article, on the basis of predecessors, works, we will propose a new fractional-order neural network model with multiple delays. Letting two different delays be bifurcation parameters and analyzing the corresponding characteristic equations of considered model, we will establish a set of new sufficient criteria to guarantee the stability and the appearance of Hopf bifurcation of fractional-order network model with multiple delays. The impact of two different delays on the stability behavior and the emergence of Hopf bifurcation of involved network model is revealed. The influence of the fractional order on the stability and Hopf bifurcation of involved model is also displayed. To check the correctness of analytical results, we perform programmer simulations with software. A conclusion is drawn in the end. The analysis results in this article are innovative and have important theoretical significance in designing neural networks. © 2019 Elsevier Inc.
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英文
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Tunable thermal rectification in graphene/hexagonal boron nitride hybrid structures
作者：
Chen, Xue-Kun* ;Hu, Ji-Wen;Wu, Xi-Jun;Jia, Peng;Peng, Zhi-Hua;...
期刊：
Journal of Physics D: Applied Physics ,2018年51(8) ISSN：0022-3727
通讯作者：
Chen, Xue-Kun
作者机构：
[Wu, Xi-Jun; Peng, Zhi-Hua; Chen, Xue-Kun; Jia, Peng; Hu, Ji-Wen] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Chen, Ke-Qiu] Hunan Univ, Sch Phys & Elect, Dept Appl Phys, Changsha 410082, Hunan, Peoples R China.;[Chen, Ke-Qiu] Synerget Innovat Ctr Quantum Effects & Applicat H, Changsha 410081, Hunan, Peoples R China.
通讯机构：
[Chen, Xue-Kun] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
thermal rectification;hybrid nanostructures;phonon resonance;molecular dynamics
摘要：
Using non-equilibrium molecular dynamics simulations, we investigate thermal rectification (TR) in graphene/hexagonal boron nitride (h-BN) hybrid structures. Two different structural models, partially substituting graphene into h-BN (CBN) and partially substituting h-BN into graphene (BNC), are considered. It is found that CBN has a significant TR effect while that of BNC is very weak. The observed TR phenomenon can be attributed to the resonance effect between out-of-plane phonons of graphene and h-BN domains in the low-frequency region under negative temperature bias. In addition, the influences of ambient temperature, system size, defect number and substrate interaction are also studied to obtain the optimum conditions for TR. More importantly, the TR ratio could be effectively tuned through chemical and structural diversity. A moderate C/BN ratio and parallel arrangement are found to enhance the TR ratio. Detailed phonon spectra analyses are conducted to understand the thermal transport behavior. This work extends hybrid engineering to 2D materials for achieving TR.<br/> ©2018 IOP Publishing Ltd.
语种：
英文
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Modeling of the control of the driven current profile in ICRF MCCD on EAST plasma
作者：
Yin, L.;Yang, C.;Gong, X. Y.* ;Lu, X. Q.;Cao, J. J.;...
期刊：
AIP Advances ,2018年8(5):055315 ISSN：2158-3226
通讯作者：
Gong, X. Y.
作者机构：
[Du, D.; Chen, Y.; Gong, X. Y.; Yin, L.] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Chen, Y.; Cao, J. J.; Wu, Z. Y.; Yin, L.; Lu, X. Q.] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Yang, C.] Chinese Acad Sci, Inst Plasma Phys, Hefei 230031, Anhui, Peoples R China.
通讯机构：
[Gong, X. Y.] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
摘要：
Control of the current profile is a crucial issue for improved confinement and the inhibition of instability in advanced tokamak operation. Using typical discharge data for the Experimental Advanced Superconducting Tokamak, numerical simulations of driven-current profile control in mode conversion current drive (MCCD) in the ion cyclotron range of frequencies were performed employing a full-wave method and Ehst-Karney efficiency formula. Results indicate that the driven current profile in MCCD can be effectively modified by shifting the mode conversion layer. The peak of the driven current can be located at an aimed position in the normalized minor radius range (-0.60≤r/a≤0) by changing the radiofrequency and the minority-ion concentration. The efficiency of the off-axis MCCD can reach 233 kA/MW through optimization, and the mode converted ion cyclotron wave plays an important role in such scenarios. The effects of electron temperature and plasma density on the driven current profile are also investigated. © 2018 Author(s).
语种：
英文
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Asymptotic solutions for the asymmetric flow in a channel with porous retractable walls under a transverse magnetic field
作者：
Guo, Hongxia;Lin, Ping* ;Li, Lin
期刊：
应用数学和力学：英文版 ,2018年39(8):1147-1164 ISSN：0253-4827
通讯作者：
Lin, Ping
作者机构：
[Lin, Ping; Guo, Hongxia] Univ Sci & Technol Beijing, Sch Math & Phys, Beijing Key Lab Magnetophotoelect Composite & Int, Beijing 100083, Peoples R China.;[Lin, Ping] Univ Dundee, Div Math, Dundee DD1 4HN, Scotland.;[Li, Lin] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Lin, Ping] U;Univ Sci & Technol Beijing, Sch Math & Phys, Beijing Key Lab Magnetophotoelect Composite & Int, Beijing 100083, Peoples R China.;Univ Dundee, Div Math, Dundee DD1 4HN, Scotland.
关键词：
laminar flow;asymmetric flow;asymptotic solution;porous and retractable channel;magnetic field
摘要：
The self-similarity solutions of the Navier-Stokes equations are constructed for an incompressible laminar flow through a uniformly porous channel with retractable walls under a transverse magnetic field. The flow is driven by the expanding or contracting walls with different permeability. The velocities of the asymmetric flow at the upper and lower walls are different in not only the magnitude but also the direction. The asymptotic solutions are well constructed with the method of boundary layer correction in two cases with large Reynolds numbers, i.e., both walls of the channel are with suction, and one of the walls is with injection while the other one is with suction. For small Reynolds number cases, the double perturbation method is used to construct the asymptotic solution. All the asymptotic results are finally verified by numerical results.
语种：
英文
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A local resonance mechanism for thermal rectification in pristine/branched graphene nanoribbon junctions
作者：
Chen, Xue-Kun* ;Liu, Jun;Xie, Zhong-Xiang;Zhang, Yong;Deng, Yuan-Xiang;...
期刊：
Applied Physics Letters ,2018年113(12):121906 ISSN：0003-6951
通讯作者：
Chen, Xue-Kun;Chen, Ke-Qiu
作者机构：
[Chen, Xue-Kun] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Liu, Jun] Cent S Univ, Coll Chem & Chem Engn, Changsha 410083, Hunan, Peoples R China.;[Xie, Zhong-Xiang; Deng, Yuan-Xiang; Zhang, Yong] Hunan Inst Technol, Dept Math & Phys, Hengyang 421002, Peoples R China.;[Chen, Ke-Qiu] Hunan Univ, Sch Phys & Elect, Dept Appl Phys, Changsha 410082, Hunan, Peoples R China.
通讯机构：
[Chen, Xue-Kun] U;[Chen, Ke-Qiu] H;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;Hunan Univ, Sch Phys & Elect, Dept Appl Phys, Changsha 410082, Hunan, Peoples R China.
摘要：
Using non-equilibrium molecular dynamics simulations, we investigate thermal rectification (TR) in pristine/branched graphene nanoribbon (GNR) junctions. The results indicate that the TR ratio of such junctions can reach 470% under small temperature bias, which has distinct superiority over asymmetric GNR and many other junctions. Moreover, the TR ratio decreases rapidly as the applied temperature bias increases. It seems to be against common sense that the TR ratio generally increases with temperature bias. Phonon spectra analyses reveal that the observed phenomena stem from the local resonance of longitudinal phonons in branched GNR region under negative temperature bias. Furthermore, the influence of ambient temperature, system length, branch number, and defect density is studied to obtain the optimum conditions for TR. This work extends local resonance mechanism to GNR for thermal signal manipulation. © 2018 Author(s).
语种：
英文
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基于有限体积法的土壤重金属污染物运移模拟
作者：
王忠康;顾晓薇;谢婷;胥孝川
期刊：
东北大学学报(自然科学版) ,2018年39(6):867-871 ISSN：1005-3026
通讯作者：
Gu, Xiao-Wei(guxiaowei@mail.neu.edu.cn)
作者机构：
[王忠康; 顾晓薇; 胥孝川] School of Resources & Civil Engineering, Northeastern University, Shenyang;110819, China;[谢婷] School of Mathematics and Physics, University of South China, Hengyang;421001, China;[王忠康; 顾晓薇; 胥孝川] 110819, China
通讯机构：
[Gu, X.-W.] S;School of Resources & Civil Engineering, Northeastern University, Shenyang, China
关键词：
饱和土壤;重金属污染物;运移;有限体积法;数值模拟
摘要：
针对重金属污染物在土壤中的运移扩散问题,采用有限体积法对二维稳态水流中污染物运移的基本方程进行离散,获得污染物在饱和土壤中运移的有限体积法计算模型.运用Matlab模拟不同条件下重金属污染物运移的动态过程,研究污染物运移规律.研究表明,当污染源始终存在时,随着时间的推移,质量浓度等值线近似由中心抛物线形渐变为外围椭圆形,水平向和竖直向浓度均不断减小;当污染源存在10天后移除时,随着时间的推移,质量浓度等值线呈椭圆形,污染范围逐渐变大,浓度不断减小,椭圆中心处浓度最大.
语种：
中文
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