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Acta Mathematicae Applicatae Sinica 2012年第4期28卷 807-822页

作者： Wan-yang dai Department of Mathematics and State Key Laboratory of Novel Software TechnologyNanjing University

In Internet environment, traffic flow to a link is typically modeled by superposition of ON/OFF based sources. During each ON-period for a particular source, packets arrive according to a Poisson process and packet sizes （hence service times） can be generally distributed. In this paper, we establish heavy traffic limit theorems to provide suitable approximations for the system under first-in first-out （FIFO） and work-conserving service discipline, which state that, when the lengths of both ON- and OFF-periods are lightly tailed, the sequences of the scaled queue length and workload processes converge weakly to short-range dependent reflecting Gaussian processes, and when the lengths of ON- and/or OFF-periods are heavily tailed with infinite variance, the sequences converge weakly to either reflecting fractional Brownian motions （FBMs） or certain type of long- range dependent reflecting Gaussian processes depending on the choice of scaling as the number of superposed sources tends to infinity. Moreover, the sequences exhibit a state space collapse-like property when the number of sources is large enough, which is a kind of extension of the well-known Little＇s law for M/M/1 queueing system. Theory to justify the approximations is based on appropriate heavy traffic conditions which essentially mean that the service rate closely approaches the arrival rate when the number of input sources tends to infinity.

关键词： reflecting fractional Brownian motion reflecting Gaussian process long-range dependence queueing process weak convergence

An Adaptive Regulation Problem and Its Application

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International Journal of Automation and computing 2017年第2期14卷 221-228页

作者： Yuan Jiang Ji-yang dai Key Laboratory of Image Processing and Pattern Recognition Nanchang Hangkong University Nanchang 330063 China School of Information Engineering Nanchang Hangkong University Nanchang 330063 China

This paper studies an adaptive regulation problem for the modified FitzHugh-Nagumo neuron model under external electrical stimulation. We first present the solution of the global robust output regulation problem for output feedback system with an uncertain exosystem which models the external electrical stimulation with unknown frequency and amplitude. Then, we show that the robust control problem for the modified FitzHugh-Nagumo neuron model can be formulated as the global robust output regulation problem and the solvability conditions for the output regulation problem for the modified FitzHugh-Nagumo neuron model are all satisfied. Then, we apply the obtained output regulation result to constructing an output feedback control law for the modified FitzHugh-Nagumo neuron model to achieve global stability of the closed-loop system in the presence of uncertain parameters and external stimulus. An example is given to show that the proposed algorithm can completely reject the external electrical stimulation.

关键词： Control theory Lyapunov methods internal model principle modified FitzHugh-Nagumo model.

Strain engineering of ion migration in LiCoO_(2)

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Frontiers of physics 2022年第1期17卷 169-176页

作者： Jia-Jing Li yang dai Jin-Cheng Zheng Department of Physics and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient DevicesXiamen UniversityXiamen361005China Department of Chemical Engineering School of Environmental and Chemical Engineeringand Institute for Sustainable EnergyShanghai UniversityShangda Road 99Shanghai200444China Department of Physics Xiamen University Malaysia439000SepangSelangorMalaysia Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry Xiamen UniversityXiamen361005China

Strain engineering is a powerful approach for tuning various properties of functional materials. The influences of lattice strain on the Li-ion migration energy barrier of lithium-ions in layered LiCoO_(2) have been systemically studied using lattice dynamics simulations, analytical function and neural network method. We have identified two Li-ion migration paths, oxygen dumbbell hop (ODH), and tetrahedral site hop (TSH) with different concentrations of local defects. We found that Li-ion migration energy barriers increased with the increase of pressure for both ODH and TSH cases, while decreased significantly with applied tensile uniaxial c-axis strain for ODH and TSH cases or compressive in-plane strain for TSH case. Our work provides the complete strain-map for enhancing the diffusivity of Li-ion in LiCoO_(2), and therefore, indicates a new way to achieve better rate performance through strain engineering.

关键词： LiCoO_(2) strain engineering migration energy barrier lithium-ion battery

Synchronization and Exponential Estimates of Complex Networks with Mixed Time-varying Coupling Delays

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International Journal of Automation and computing 2009年第3期6卷 301-307页

作者： yang dai Yun-Ze Cai Xiao-Ming Xu Department of Automation Shanghai Jiao Tong University Shanghai 200240 PRC University of Shanghai for Science and Technology Shanghai 200093 PRC Shanghai Academy of Systems Science Shanghai 200093 PRC

Exponential estimates and sufficient conditions for the exponential synchronization of complex dynamical networks with bounded time-varying delays are given in terms of linear matrix inequalities （LMIs）. A generalized complex networks model involving both neutral delays and retarded ones is presented. The exponential synchronization problem of the complex networks is converted equivalently into the exponential stability problem of a group of uncorrelated delay functional differential equations with mixed timevarying delays. By utilizing the free weighting matrix technique, a less conservative delay-dependent synchronization criterion is derived. An illustrative example is provided to demonstrate the effectiveness of the proposed method.

关键词： Complex networks synchronization exponential estimates neutral delay time-varying delay.

Effect of Laminar Cooling on Phase Transformation Evolution in Hot Rolling Process

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Journal of Iron and Steel Research International 2010年第10期17卷 28-32,44页

作者： NING Lin-xin yang dai-jun J Lin T A Dean Shougang Technology Institute Shougang Group Beijing 100041 China Department of Mechanical and Manufacturing Engineering University of Birmingham Birmingham B15 2TT UK

The effect of temperature variation owing to the cooling pattern （CP） on the microstructural evolution was investigated by establishing a thermomechanical coupled FE （finite element） model. A set of constitutive equations of phase transformation was implanted into the commercial FE solver MARC through the user defined subroutine CR- PLAW, and the temperature field was calculated by another user defined subroutine FILM. The results show that the final mierostructure is completely bainite phase for CP one, 98% of bainite phase and 2% of ferrite phase for CP two, and 55% of bainite phase, 35% of pearlite phase and 10% of ferrite phase for CP three.

关键词： hot rolling laminar cooling system cooling pattern thermomechanical modelling microstructural evolution constitutive equation phase transformation

Blend with the Sea Surface Temperature from Different Satellites and Their Comparison in the Southeast Pacific Ocean

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Journal of Ocean University of China 2023年第2期22卷 452-458页

作者： WU Yumei TANG Fenghua dai yang WANG Fei SHI Yongchuang ZHANG Shengmao Key and Open Laboratory of Remote Sensing Information Technology in Fishing Resource East China Sea Fisheries Research InstituteChinese Academy of Fishery SciencesShanghai 200090China Key Laboratory of Fisheries Remote Sensing Ministry of Agriculture and Rural Affairs Shanghai 200090China

The daily sea surface temperature(SST)data from three kinds of different satellites of GMI,GOES and MODIS were applied to do the blend in the Southeast Pacific Ocean throughout the whole year of *** coverage rates of the SST of the blend result were improved highly and more stable throughout the whole year,compared with the result of the single satellite of GMI,GOES,and *** yearly average coverage rates of GMI,GOES,MODIS,and blend were 43%,48%,30%,and 76%,and their corresponding yearly average standard deviation(SD)were 4%,6%,7%,and 4%,*** the coverage rates of these three satellites were low from April to *** valid observation days calculated in the whole year over every grid were used to represent the spatial distribution patterns of the coverage *** spatial distribution patterns of coverage rates from GOES and MODIS were similar that their valid observation days were higher in the northwest area and lower in the south area,and those of GMI was contrary to the former *** ranges of valid observation day was from GOES,GMI,and MODIS were 0-364,6-254,and 9-231 d,*** the blend,all the observation day of every grid in the research region was enhanced(103-366 d).Especially the near shore and south area,and the minimum valid observation day increased largely from the single digits to hundreds digit.

关键词： sea surface temperature blend coverage rate observation day

Effect of Al_(2)O_(3)/SiO_(2) ratio on morphology of complex calcium ferrite

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Journal of Iron and Steel Research International 2023年第10期30卷 1921-1928页

作者： dai-wei yang Wei Wang Jing-xuan Li Xu-heng Chen Peng-fei Chen Jiangsu Yonggang Group Co. Ltd.IronworksSuzhou 215600JiangsuChina Hubei Provincial Engineering Technology Research Center of Metallurgical Secondary Resources Wuhan University of Science and TechnologyWuhan 430081HubeiChina Beijing Zhiye Interconnection Technology Co. Ltd.Beijing 100144China

Al_(2)O_(3) and SiO_(2) greatly influence the formation of complex calcium ferrite,which is the main bonding phase in high basicity *** effects of Al_(2)O_(3)/SiO_(2) ratios on the morphology of complex calcium ferrite were *** main mineral phases in the samples with different Al_(2)O_(3)/SiO_(2) ratios were CaFe_(2)O_(4) with a solid solution of Si or Al atoms and the silico-ferrite of calcium and *** results showed that the morphology of the complex calcium ferrite changed from lumpy to plate-like and acicular with increases in the SiO_(2) content and the Al_(2)O_(3)/SiO_(2) *** the content of SiO_(2) was 4 wt.%,the main calcium ferrite morphology was acicular,and the number of macropores in the samples increased with the Al_(2)O_(3)/SiO_(2) ratio *** first-principles analysis of the calcium ferrite crystal structure showed that adding SiO_(2) and Al_(2)O_(3) changed the growth mechanism of the CaFe_(2)O_(4) crystal,promoting the formation of platy and acicular complex calcium *** size of calcium ferrite was significantly smaller due to the increase in CaO-Fe_(2)O_(3)-SiO_(2)-Al_(2)O_(3) viscosity with increasing the Al_(2)O_(3)/SiO_(2) ratio.

关键词： Complex calcium ferrite Silico-ferrite of calcium and aluminum Al_(2)O_(3)/SiO_(2)ratio Morphology First-principles calculation

DETACHED EDDY SIMULATION OF HYDRAULIC CHARACTERISTICS ALONG THE SIDE-WALL AFTER A NEW ARRANGEMENT-SCHEME OF THE SUDDEN LATERAL ENLARGEMENT AND THE VERTICAL DROP

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Journal of Hydrodynamics 2011年第5期23卷 669-675页

作者： LI Guo-jing dai Guang-qing yang Qing MA Xu-dong State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University Chengdu 610065 China

In order to study the cavitation damage in a side-wall when a sudden lateral enlargement and a vertical drop are imposed at the radial gate, a new arrangement-scheme is proposed, where the sudden lateral enlargement and the vertical drop can be imposed at the outlet of the gate chamber. The hydraulic characteristics along the side-wall are simulated by the detached eddy simulation and the Volume Of Fluid （VOF） method. The numerical results agree well with those of experiment. The experimental and numerical results show that the flow condition is smooth with only a weak water-wing appearing behind the lateral cavity, and the length of the lateral cavity becomes longer and is mainly affected by the size of the lateral enlargement and the zone of negative pressure after the water impacts the side-wall would disappear. The hydraulic characteristics of the new arrangement-scheme are beneficial to the prevention of the cavitation damage in the side-wall and the Detached Eddy Simulation （DES） with the VOF method can well predict the hydraulic characteristics after the new arrangement-scheme of the sudden lateral enlargement and the vertical drop.

关键词： model test aeration to prevent cavitation damage realizable k - ε turbulent model Detached Eddy Simulation (DES) Volume Of Fluid (VOF) method

Magnetic resonance imaging assessment of the lateral geniculate nucleus volume and height in patients with glaucoma:a Meta-analysis

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International Journal of Ophthalmology(English edition) 2023年第4期16卷 638-644页

作者： Hai-Jian Hu Yi-Li Chang yang-yang dai Yu-Lin Yu Xu Zhang Affiliated Eye Hospital of Nanchang University Jiangxi Research Institute of Ophthalmology and Visual ScienceJiangxi Clinical Research Center for Ophthalmic DiseaseJiangxi Branch of National Clinical Research Center for Ocular DiseasesNanchang 330006Jiangxi ProvinceChina

AIM:To evaluate the lateral geniculate nucleus(LGN)volume and height using magnetic resonance imaging(MRI)in glaucoma ***:Literatures retrieval was carried out through Pub Med,Web of Science,Embase,and Cochrane *** that compared the volume and height of LGN in glaucoma patients with that in control subjects were *** volume and height of LGN were extracted from the included *** Review Manager 5.4.1 software was used for the ***:This Meta-analysis included 10 crosssectional studies,including the eyes of 223 glaucoma patients and 185 healthy *** with the control subjects,the volume and height of LGN in glaucoma patients measured by MRI were significantly reduced{-29.13 mm3,95%[confidence interval(CI):-44.82 to-13.43,P=0.0003;-0.61 mm,95%CI:-0.78 to-0.44,P<0.00001,respectively]}.Subgroup analysis demonstrated that the differences of LGN volume and height between glaucoma patients and control subjects in the older group were smaller than that in the younger group,and LGN volume decreased with the increase of glaucoma ***:The results demonstrate that the volume and height of LGN are decreased in glaucoma patients,and LGN volume can be considered a parameter of glaucoma severity.

关键词： magnetic resonance imaging lateral geniculate nucleus glaucoma Meta-analysis

A novel method for identifying influential nodes in complex networks based on gravity model

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Chinese Physics B 2022年第5期31卷 791-801页

作者： Yuan Jiang Song-Qing yang Yu-Wei Yan Tian-Chi Tong Ji-yang dai School of Information Engineering Nanchang Hangkong UniversityNanchang 330063China School of Automation Nanjing University of TechnologyNanjing 210094China

How to identify influential nodes in complex networks is an essential issue in the study of network characteristics.A number of methods have been proposed to address this problem,but most of them focus on only one *** on the gravity model,a novel method is proposed for identifying influential nodes in terms of the local topology and the global *** method comprehensively examines the structural hole characteristics and K-shell centrality of nodes,replaces the shortest distance with a probabilistically motivated effective distance,and fully considers the influence of nodes and their neighbors from the aspect of *** eight real-world networks from different fields,the monotonicity index,susceptible-infected-recovered(SIR)model,and Kendall’s tau coefficient are used as evaluation criteria to evaluate the performance of the proposed method compared with several existing *** experimental results show that the proposed method is more efficient and accurate in identifying the influence of nodes and can significantly discriminate the influence of different nodes.

关键词： influential nodes gravity model structural hole K-shell