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Search Results: 1 - 10 of 23395 matches for " AiJun He "
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Multifractal mass exponent spectrum of complex physiological time series
XiaoDong Yang,AiJun He,Yong Zhou,XinBao Ning
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-3276-3
Abstract: Physiological signal belongs to the kind of nonstationary and time-variant ones. Thus, the nonlinear analysis methods may be better to disclose its characteristics and mechanisms. There have been plenty of evidences that physiological signal generated by complex self-regulated system may have a fractal structure. In this work, we introduce a new measure to characterize multifractality, the mass exponent spectrum curvature, which can disclose the complexity of fractal structure from total bending degree of the spectrum. This parameter represents the nonlinear superpositions of the discrepancies of fractal dimension from all adjacent points in the curve and therefore solves the problem of original parameters for not fully reflecting the information of entire subsets in the fractal structure. The evaluations of deterministic fractal system Cantor measure validate that it is completely effective in exploring the complexity of chaotic series, and is also not affected by nonstability of the signal as well as disturbances of the noises. We then apply it to the analysis of human heart rate variability (HRV) signals and sleep electroencephalogram (EEG) signals. The experimental results show that this method can be better to discriminate cohorts under different physiological and pathological conditions. Compared with the indicator of singularity spectrum width, there are some improvements both on the computing efficiency and accuracy. Such conclusion may provide some valuable information for clinical diagnoses.
Complexity and characteristic frequency studies in ECG signals of mice based on multiple scale factors
XiaoDong Yang,AiJun He,Peng Liu,TongFeng Sun,XinBao Ning
Science China Life Sciences , 2011, DOI: 10.1007/s11427-011-4173-y
Abstract: Existing methods of physiological signal analysis based on nonlinear dynamic theories only examine the complexity difference of the signals under a single sampling frequency. We developed a technique to measure the multifractal characteristic parameter intimately associated with physiological activities through a frequency scale factor. This parameter is highly sensitive to physiological and pathological status. Mice received various drugs to imitate different physiological and pathological conditions, and the distributions of mass exponent spectrum curvature with scale factors from the electrocardiogram (ECG) signals of healthy and drug injected mice were determined. Next, we determined the characteristic frequency scope in which the signal was of the highest complexity and most sensitive to impaired cardiac function, and examined the relationships between heart rate, heartbeat dynamic complexity, and sensitive frequency scope of the ECG signal. We found that all animals exhibited a scale factor range in which the absolute magnitudes of ECG mass exponent spectrum curvature achieve the maximum, and this range (or frequency scope) is not changed with calculated data points or maximal coarse-grained scale factor. Further, the heart rate of mice was not necessarily associated with the nonlinear complexity of cardiac dynamics, but closely related to the most sensitive ECG frequency scope determined by characterization of this complex dynamic features for certain heartbeat conditions. Finally, we found that the health status of the hearts of mice was directly related to the heartbeat dynamic complexity, both of which were positively correlated within the scale factor around the extremum region of the multifractal parameter. With increasing heart rate, the sensitive frequency scope increased to a relatively high location. In conclusion, these data provide important theoretical and practical data for the early diagnosis of cardiac disorders.
Fractal Image Coding

He Aijun,Ma Zhengming,

中国图象图形学报 , 1999,
Abstract: This is an overview on fractal image coding. On the base of collecting and reading related documents, we describe the current research status of fractal image coding and make a remark on its prospect.
Fast Fractal Image Coding

He Aijun,Ma Zhengming,

中国图象图形学报 , 1999,
Abstract: This paper presents a new method for fast fractal image coding. This method speeds up the coding process by adaptive partition of image, moment classification of domain pool, orthogonal decomposition of domain blocks and range blocks, as well as dynamic search by pixel after pixel. The experimental results show that the method presented in this paper performs well in speeding up the coding process, especially for those images that have much more details in them.
Fractal Image Coding in the Frequency Domain

He Aijun,Ma Zhengming,

中国图象图形学报 , 1998,
Abstract: This paper presents a new scheme of fractal coding in the frequency domain. Compared with fractal coding in the spatial domain,the proposed scheme has two features: segmented luminance transform, simplification and combination of geometrical transform. Theory analysis and experiment show that this scheme is superior in encoding time and decoder contractility. Meanwhile, it shares alittle higher compression ratio and higher image fidelity.
Behavior and mechanism of napropamide adsorption in soil-water environment

MA Aijun,HE Renhong,ZHOU Lixiang,

环境科学学报 , 2006,
Abstract: 采用高效液相色谱法(HPLC)测定了土壤、胡敏酸及粘土矿物对除草剂草萘胺的吸附效应,并用FTIR图谱分析对其吸附机理进行了研究.结果表明,草萘胺在5种土壤上的吸附均很好地符合Freundlich方程,吸附常数Kf值在3.98~12.82之间.5种土壤对草萘胺吸附容量大小的次序为:黄泥土>黑土>黄棕壤>红壤>潮土.将吸附常数Kf与土壤的理化性质进行多元逐步回归分析表明,土壤有机碳含量与草萘胺吸附容量呈线性关系(R2=0.997,p<0.05 n=5).红外光谱分析结果表明,草萘胺可能通过脂肪族分配及疏水吸附等形式与HA发生了结合.
The Operator of Genetic Algorithms to Improve its Properties
Aijun Li
Modern Applied Science , 2010, DOI: 10.5539/mas.v4n3p60
Abstract: Based on the traditional genetic algorithm, proposed an improved adaptive genetic algorithm, the experimental results show that the improved adaptive genetic algorithm results than standard genetic algorithm much better and effective to improve the convergence of genetic algorithm optimization of speed and efficiency.
Dynamic Reliability Calculation of Bridge Based on Quasi-non-integrable-Hamiltonian System Theory

赫中营, 王根会, 叶爱君, 夏修身
HE Zhongying
, WANG Genhui, YE Aijun, XIA Xiushen

- , 2016,
Abstract: 摘要: 为提高铁路桥梁动力可靠度计算的效率,考虑结构非线性,基于振型空间,导出了铁路桥梁动能和势能的表达式,进而根据拟Hamilton系统理论确定铁路混凝土桥梁的广义动量、广义速度、Hamilton函数及拟Hamilton系统方程.只考虑横向位移和扭转位移,导出了铁路混凝土桥梁的拟不可积Hamilton系统方程,得到条件可靠度函数应满足的后向Kolmogorov方程及其定量边界、初值条件,并用中心差分法求解该方程.以实际铁路桥梁为算例,用上述方程求解其在列车荷载作用下的动力可靠度.研究结果表明:非线性桥梁结构的动力可靠度和概率密度峰值随桥梁初始能量增大而减小,随桥梁临界能量增大而增大;不同跨度桥梁的分析结果与实际情况相符,说明基于拟不可积Hamilton系统理论计算铁路桥梁的非线性动力可靠度是可行的.
Abstract: To improve the computation efficiency of bridge dynamic reliability, kinetic energy and potential energy of a railway bridge with nonlinear characteristics were expressed in the modal space, and the generalized momentum, the generalized velocity, the Hamiltonian function and the quasi-Hamiltonian system equation were established based on the quasi-Hamiltonian system theory. A quasi-non-integrable-Hamiltonian equation for a railroad concrete bridge was derived just considering its lateral and torsion displacements, and the backward Kolmogorov (BK) equation governing conditional reliability function and its corresponding quantitative boundary and initial conditions were obtained, and the central finite difference method was introduced to calculate the BK equation. The case research results show that the dynamic reliability of a nonlinear bridge structure and the peak value of probability density decrease as the primary energy increases, while they increase as the limit energy raises; and the contrastive analysis results of railway bridges with different spans are agreed with the actual situations, illustrating that the dynamic reliability calculation of railway bridges based on the quasi-non-integrable-Hamiltonian system theory is feasible
Mesoscale eddy effects on the wintertime vertical mixing in the formation region of the North Pacific Subtropical Mode Water
Pan Aijun,Liu Qinyu
Chinese Science Bulletin , 2005, DOI: 10.1360/982004-757
Abstract: Mesoscale eddy effects on the wintertime vertical mixing in the formation region of the North Pacific Subtropical Mode Water (NPSTMW) are studied using hydrographic data from Argo profiling floats deployed in the Kuroshio recirculation region in February and March of 2001. Anticyclonic (warm) eddy enhances the wintertime vertical mixing and results in the deep mixed layer and the deep thermocline. Consequently, a large volumetric water mass with low potential vorticity corresponding to the prototype of NPSTMW tends to be formed. By contrast, cyclonic (cold) eddy is unfavorable for the vertical mixing process and halts the deepening of the mixed layer and thus the formation of mode water. Further analysis shows that cyclonic eddies prevail in the late 1990s in the formation region of NPSTMW, which lead to significant suppression of the wintertime vertical mixing (96–98) and thus are unfavorable for the formation of NPSTMW; while the situation is completely reversed in the early 1990s (93–95).
Geometric version of mixed mean inequalities
Yuan Jun,Li Aijun
Tamkang Journal of Mathematics , 2009, DOI: 10.5556/j.tkjm.40.2009.129-137
Abstract: In this paper, we introduce the mixed mean of star bodies and give geometric version of mixed mean inequalities.
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