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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 485-491页

作者： FENG Shaotong HAN Dianrong DING Heping Department of Physics Nanjing Normal University Nanjing 210097 China Department of Physics Nanjing Normal University Nanjing 210097 China Department of Physics Nanjing Normal University Nanjing 210097 China

By means of experimental technique of optical fractional Fourier transform, we have determined the hurst exponent of a regular self-affine fractal pattern to demonstrate the feasibility of this approach. Then we extend this method to determine the hurst exponents of some irregular self-affine fractal patterns. Experimental results show that optical fractional Fourier transform is a practical method for analyzing the self-affine fractal patterns.

关键词： optical fractional Fourier transform, seff-affine fractal, hurst exponent.

基于AOS的hurst-优先级自适应RED与动态调度算法

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通信学报 2012年第10期33卷 156-165页

作者：别玉霞潘成胜刘海燕王延春南京理工大学自动化学院江苏南京210094 大连大学信息工程学院辽宁大连116622 辽宁省通信网络与信息处理重点实验室辽宁大连116622

为有效传输空间数据系统中多类型、大容量、突发性的数据,基于高级在轨系统(AOS)虚拟信道复用技术,提出了一种自相似参数hurst-优先级自适应的随机早检测(RED)与动态调度算法——HPRED-DS。该算法在队列管理中设计了基于hurst参数与优... 详细信息

为有效传输空间数据系统中多类型、大容量、突发性的数据,基于高级在轨系统(AOS)虚拟信道复用技术,提出了一种自相似参数hurst-优先级自适应的随机早检测(RED)与动态调度算法——HPRED-DS。该算法在队列管理中设计了基于hurst参数与优先级的2级丢弃分组策略,在虚拟信道调度中设计了VIP/同步/异步混合的动态调度模式,并将队列管理与虚拟信道调度有效结合起来。实验结果表明该算法在保持高处理效率和吞吐率的基础上,稳定了队列长度,降低了排队延时和延时抖动,并能满足AOS中不同业务的传输要求。

关键词：虚拟信道队列管理 hurst 优先级动态调度

消失矩对小波分析求解自相似参数hurst的影响研究

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电子与信息学报 2007年第9期29卷 2257-2261页

作者：任勋益王汝传祁正华南京邮电大学计算机学院南京210003

研究了消失矩对小波求解自相似参数hurst值的影响,给出了理论推导和分析,间接论证了消失矩对hurst参数求解的影响趋势,通过大量的实验结果给出了详细情况。理论和实验结果一致表明,在局部上,hurst参数随着消失矩的增大呈现周期性变化,... 详细信息

研究了消失矩对小波求解自相似参数hurst值的影响,给出了理论推导和分析,间接论证了消失矩对hurst参数求解的影响趋势,通过大量的实验结果给出了详细情况。理论和实验结果一致表明,在局部上,hurst参数随着消失矩的增大呈现周期性变化,但总的趋势是随着消失矩的增大hurst值减小,误差在增大,满足条件的最小消失矩是最佳选择。该结论能为基于自相似和小波分析的大量应用提供理论依据。

关键词：消失矩小波自相似 hurst

An Approach to Dynamic Asymptotic Estimation for hurst Index of Network Traffic

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International Journal of Communications, Network and System Sciences 2010年第2期3卷 167-172页

作者： Xiaoyan MA Hongguang LI 不详

As an important parameter to describe the sudden nature of network traffic, hurst index typically conducts behaviors of both self-similarity and long-range dependence. With the evolution of network traffic over time, more and more data are generated. hurst index estimation value changes with it, which is strictly consistent with the asymptotic property of long-range dependence. This paper presents an approach towards dynamic asymptotic estimation for hurst index. Based on the calculations in terms of the incremental part of time series, the algorithm enjoys a considerable reduction in computational complexity. Moreover, the local sudden nature of network traffic can be readily captured by a series of real-time hurst index estimation values dynamically. The effectiveness and tractability of the proposed approach are demonstrated through the traffic data from OPNET simulations as well as real network, respectively.

关键词： Network Traffic hurst Index Dynamic Asymptotic Estimation Long-Range Dependence

Spontaneous combustion influenced by surface methane drainage and its prediction by rescaled range analysis

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International Journal of Mining Science and Technology 2018年第2期28卷 215-221页

作者： Shengqiang Yang Xincheng Hu Wei Victor Liu Jiawen Cai Xiuhong Zhou School of Safety Engineering China University of Mining&TechnologyXuzhou 221008China Key Laboratory of Gas and Fire Control for Coal Mines Xuzhou 221008China Department of Civil&Environmental Engineering University of AlbertaEdmonton T6G 2W2Canada

This study established numerical modeling using COMSOLTMto examine the influence of horizontal location and drainage ability of surface borehole on spontaneous combustion in longwall working face gob. Rescaled Range Analysis(R/S analysis) was employed to investigate the chaos characteristic of N_2/O_2 ratio from a surface borehole in 10416 working face gob, Yangliu Colliery, China. The simulation results show that there is always a circular ‘‘dissipation zone" around the drainage borehole and an elliptic ‘‘spontaneous combustion zone" in deep gob. Little influence was found on spontaneous combustion zone on the intake side of the gob but the width of spontaneous combustion zone in middle gob is enlarged, while the depth of spontaneous combustion zone near the return side is reduced. The R/S analysis indicates that the influence of surface borehole on spontaneous combustion can be divided into two stages by the chaos feature of N_2/O_2: safety drainage stage and spontaneous combustion initiating stage. It can be concluded that the methane drainage from gob through surface borehole can intervene in the distribution of spontaneous combustion zone in gob and the chaos feature of N_2/O_2 from surface borehole can effectively reflect coal spontaneous combustion condition in gob.

关键词： Coal spontaneous combustion Surface drainage borehole hurst index Rescaled range analysis Methane drainage Symbiotic disaster

Extrapolation reconstruction of wind pressure fields on the claddings of high-rise buildings

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 653-666页

作者： Yehua SUN Guquan SONG Hui LV School of Civil Engineering and Architecture Nanchang UniversityNanchang 330033China Jiangxi Institute of Economic Administrators Nanchang 330038China

Recent research about reconstruction methods mainly used the interpolation reconstruction of the fluctuating wind pressure field on the surface.However,to investigate wind pressure at the edge of the building,the work presented in this paper focuses on the extrapolation reconstruction of wind pressure fields.Here,we propose an improved proper orthogonal decomposition(POD)and Kriging method with a von Karman correlation function to resolve this issue.The studies show that it works well for not only interpolation reconstruction but also extrapolation reconstruction.The proposed method does require determination of the hurst exponent and other parameters analysed from the original data.Hence,the fluctuating wind fields have been characterized by the von Karman correlation function,as an a priori function.Compared with the cubic spline method and different variogram,preliminary results suggest less time consumption and high efficiency in extrapolation reconstruction at the edge.

关键词： extrapolation reconstruction proper orthogonal decomposition Kriging method von Karman function hurst exponent rescaled range analysis

Three-dimensional analysis of spreading and mixing of miscible compound in heterogeneous variable-aperture fracture

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Water Science and Engineering 2016年第4期9卷 293-299页

作者： Zhi Dou Zhi-fang Zhou Jin-guo Wang Department of Civil Engineering University of Toronto School of Earth Sciences and Engineering Hohai University

As mass transport mechanisms,the spreading and mixing(dilution) processes of miscible contaminated compounds are fundamental to understanding reactive transport behaviors and transverse dispersion.In this study,the spreading and dilution processes of a miscible contaminated compound in a three-dimensional self-affine rough fracture were simulated with the coupled lattice Boltzmann method(LBM).Moment analysis and the Shannon entropy(dilution index) were employed to analyze the spreading and mixing processes,respectively.The corresponding results showed that the spreading process was anisotropic due to the heterogeneous aperture distribution.A compound was transported faster in a large aperture region than in a small aperture region due to the occurrence of preferential flow.Both the spreading and mixing processes were highly dependent on the fluid flow velocity and molecular diffusion.The calculated results of the dilution index showed that increasing the fluid flow velocity and molecular diffusion coefficient led to a higher increasing rate of the dilution index.

关键词： Mixing Spreading Solute transport Three-dimensional fracture Self-affinity hurst exponent

Prediction analysis of long-term memory effect for calamity gray series

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Science China Earth Sciences 2004年第3期47卷 209-220页

作者： CHEN Zhaonan (CHEN Chaonan)1 & LI Zongyang (LEE Tzongyeang)2 1. Department of Earth Sciences, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan, China 2. Department of Information Management, Leader University, No. 188, Sec 5, Au-Chung Road, Tainan 70901, Taiwan, China Department of Earth Sciences National Cheng Kung University 1 Ta-Hsueh Road Tainan 70101 Taiwan Department of Information Management Leader University No. 188 Sec 5 Au-Chung Road Tainan 70901 Taiwan

It is adequate to use the gray theory for modeling and forecasting short-term calamity series. The forecast of calamity gray series is equivalent to predicting an extraordinary event in nature. In order to look for the regularity, the calamity date series, created from the threshold for a fixed time-interval series, are studied. In this paper, the hurst exponent is applied to defining the long-term memory effect of the simulated calamity series, and is tested for the feasibility of using it as pre-requisite information before the gray modeling and forecasting. Based on the fractional Brownian motion (fBm) model, the time series with a definite length or quantity of data are derived assuming that various kinds of memory effect exist. Different threshold values are defined to yield or to analogize the calamity date series that are required in the prediction of the gray calamity events. After case study, both of the simulated and real seismic data show that the hurst exponents are greater than 0.5 and, therefore, indicate that the long-term memory ef-fect exists. The correlation between the hurst exponent and the gray modeling parameter, a, provides criteria for the classification of the forecast.

关键词： gray theory, calamity series, hurst exponent, long-term memory effect, fractional Brownian motion.

Spatiotemporal dynamics of the vegetation in Ningxia,China using MODIS imagery

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Frontiers of Earth Science 2020年第1期14卷 221-235页

作者： Yi HE Haowen YAN Lei MA Lifeng ZHANG Lisha QIU Shuwen YANG Faculty of Geomatics Lanzhou Jiaotong UniversityLanzhou 730700China National-Local Joint Engineering Research Center of Technologies and Applications for National Geographic State Monitoring Lanzhou Jiaotong UniversityLanzhou 730700China Gansu Provincial Engineering Laboratory for National Geographic State Monitoring Lanzhou Jiaotong UniversityLanzhou 730700China

The vegetation in the Ningxia Hui Autonomous Region(henceforth,Ningxia)of north-western China plays an important role in guarding regional ecological safety and sustainable development.However,it is unclear how climate affects vegetation growth in terms of seasonality and various vegetation types in Ningxia.Based on remote sensing vegetation index from 2001 to 2016,climatic parameters,and the Chinese vegetation type data,this article examines the spatiotemporal effects of climate parameters on vegetation.The relative importance to variability in the normalized difference vegetation index(NDVI)for different seasons and various vegetated types is also determined.The results demonstrate that the vegetation increased from 2001 to 2016 in Ningxia.The rate of NDVI increase was fastest in summer and slowest in spring.Areas with significant increases in vegetation occurred primarily in the southern mountain,Liupan Mountain,and central arid areas.Degraded vegetation occurred in the Yellow River irrigation area with intense human activity influence.The vegetation in most areas of Ningxia will continue to increase in the future.The sensitivity of vegetation to temperature,precipitation,sunshine duration,and wind velocity showed significantly seasonal variability.Sunshine duration and wind velocity were important climatic factors affecting vegetation growth in Ningxia.However,the impact of summer precipitation variation on summer NDVI(SMN)demonstrated a time lag effect.The impact of climate variation on vegetation was distinct among various vegetation types.Moreover,the spatial pattern of vegetation in Ningxia was also impacted by human activities.

关键词： spatiotemporal patterns vegetation NDVI climatic parameter hurst exponent Ningxia

Study on Self-adaptive Systematic Double Sampling method for Self-similar Network Traffic

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China Communications 2007年第2期4卷 86-89页

作者： Liu Yuanzhen Liu Yuan Li Xiaohang So Yangtze Univ Sch Informat Engn Wuxi Jiangsu 214122 Peoples R China

This paper proposes anew variation of systematic sampling, called Self-Adaptive Systematic Double Sampling(SSDS). This algorithm can fully consider the self-similar and heavy-tailed distribution characteristics of network traffic and estimate hurst parameter correctly.The experiments on real Internet traces indicate,compared with traditional sampling methods,the new method advances the accuracy and practicability of the sampling measuring system obviously,and can achieve simplicity,adaptability and controllability of resource consumption.

关键词： self-similarity hurst parameter double sampling