The aim of this study is to estimate the chaos phenomenon in temporomandibular joints (TMJ) sound using fractal dimension (FD),and to examine the diagnostic value of the FD in comparing TMJ sounds produced by 6 asympt...The aim of this study is to estimate the chaos phenomenon in temporomandibular joints (TMJ) sound using fractal dimension (FD),and to examine the diagnostic value of the FD in comparing TMJ sounds produced by 6 asymptomatic and 25 symptomatic TMJ. Multiple mandibular opening and closing cycles recorded were used to calculate the waveform dimension and correlation dimension in the FD. Chaos in the TMJ sounds was estimated by the FD that was saturated with some constant value to an increase of embedding dimension. Results reveal that fractal analysis produces a high degree of reproducibility within,and similarity across subjects,and indicate that both FD values of the asymptomatic TMJ sounds are significantly higher than those of the symptomatic. These findings suggest that chaos is present in TMJ sounds and the difference in the FD is of diagnostic value in evaluation of pathological change in TMJ sound signals.展开更多
We analyze muscular dystrophy recorded by sEMG and use standard methodologies and nonlinear chaotic methods here including the RQA. We reach sufficient evidence that the sEMG signal contains a large chaotic component....We analyze muscular dystrophy recorded by sEMG and use standard methodologies and nonlinear chaotic methods here including the RQA. We reach sufficient evidence that the sEMG signal contains a large chaotic component. We have estimated the correlation dimension (fractal measure), the largest Lyapunov exponent, the LZ complexity and the %Rec and %Det of the RQA demonstrating that such indexes are able to detect the presence of repetitive hidden patterns in sEMG which, in turn, senses the level of MU synchronization within the muscle. The results give also an interesting methodological indication in the sense that it evidences the manner in which nonlinear methods and RQA must be arranged and applied in clinical routine in order to obtain results of clinical interest. We have studied the muscular dystrophy and evidence that the continuous regime of chaotic transitions that we have in muscular mechanisms may benefit in this pathology by the use of the NPT treatment that we have considered in detail in our previous publications.展开更多
The paper discusses the fundamental conceptions and properties of fractal geometry.The definitions of fractal dimension are described and the mathods of calculating fractal dimension are introduced. The paper research...The paper discusses the fundamental conceptions and properties of fractal geometry.The definitions of fractal dimension are described and the mathods of calculating fractal dimension are introduced. The paper researches the peculiarities of fault diagnosis for logging truck engine and puts forward the technical way of diagnosing the faults with the help of the fractal geometry.展开更多
This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-cou...This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-counting fractal dimensions and five representative period parameters of near-fault ground motions from the Chi-Chi and Northridge earthquakes are calculated and compared. Numerical results indicate that the acceleration and velocity time histories of ground motions present the statistical fractal property, and the dominant pulses of near-fault ground motions have a significant influence on their box dimensions and periods. Further, the average box dimension of near-fault impulsive ground motions is smaller, and their irregular degree of wave forms is lower. Moreover, the box dimensions of ground motions reflect their frequency properties to a large extent, and can be regarded as an alternative indicator to represent their frequency content. Finally, the box dimension D of the acceleration histories shows a considerably negative correlation with the mean period T. Meanwhile, the box dimension of the velocity histories Dye is negatively correlated with the characteristic period T and improved characteristic period Tgi.展开更多
According to the definition of correlation dimension in fractal theory, this paper presented a method to determine and assess noise part in detected transient signal. Such work is essential to decrease the noise part ...According to the definition of correlation dimension in fractal theory, this paper presented a method to determine and assess noise part in detected transient signal. Such work is essential to decrease the noise part in the detected signal. It is proved that heart period signal (HPS) is one typical sort of transient chaotic signal. Through experiment and simulation, the analysis of chaotic HPS in the detected signal was done. In the end, we deepen the researches on attractor dimension of HPS for persons who are different in age.展开更多
总结了关联维数和K o lm ogorov熵的计算方法,给出详细的计算步骤,并通过对某型发动机在不同状态下关联维数和K o lm ogorov熵的计算和混沌特性分析,提出一种将关联维数和K o lm ogorov熵结合使用的新的故障诊断手段。实验结果表明:由...总结了关联维数和K o lm ogorov熵的计算方法,给出详细的计算步骤,并通过对某型发动机在不同状态下关联维数和K o lm ogorov熵的计算和混沌特性分析,提出一种将关联维数和K o lm ogorov熵结合使用的新的故障诊断手段。实验结果表明:由于不同故障的动力学产生机制不同,通常也具有不同的关联维数和K o l-m ogorov熵,故关联维数和K o lm ogorov熵可用于故障的特征提取。展开更多
基金The Scientific Research Fund of Tianjin Medical UniversityGrant number:98KY21
文摘The aim of this study is to estimate the chaos phenomenon in temporomandibular joints (TMJ) sound using fractal dimension (FD),and to examine the diagnostic value of the FD in comparing TMJ sounds produced by 6 asymptomatic and 25 symptomatic TMJ. Multiple mandibular opening and closing cycles recorded were used to calculate the waveform dimension and correlation dimension in the FD. Chaos in the TMJ sounds was estimated by the FD that was saturated with some constant value to an increase of embedding dimension. Results reveal that fractal analysis produces a high degree of reproducibility within,and similarity across subjects,and indicate that both FD values of the asymptomatic TMJ sounds are significantly higher than those of the symptomatic. These findings suggest that chaos is present in TMJ sounds and the difference in the FD is of diagnostic value in evaluation of pathological change in TMJ sound signals.
文摘We analyze muscular dystrophy recorded by sEMG and use standard methodologies and nonlinear chaotic methods here including the RQA. We reach sufficient evidence that the sEMG signal contains a large chaotic component. We have estimated the correlation dimension (fractal measure), the largest Lyapunov exponent, the LZ complexity and the %Rec and %Det of the RQA demonstrating that such indexes are able to detect the presence of repetitive hidden patterns in sEMG which, in turn, senses the level of MU synchronization within the muscle. The results give also an interesting methodological indication in the sense that it evidences the manner in which nonlinear methods and RQA must be arranged and applied in clinical routine in order to obtain results of clinical interest. We have studied the muscular dystrophy and evidence that the continuous regime of chaotic transitions that we have in muscular mechanisms may benefit in this pathology by the use of the NPT treatment that we have considered in detail in our previous publications.
文摘The paper discusses the fundamental conceptions and properties of fractal geometry.The definitions of fractal dimension are described and the mathods of calculating fractal dimension are introduced. The paper researches the peculiarities of fault diagnosis for logging truck engine and puts forward the technical way of diagnosing the faults with the help of the fractal geometry.
基金National Natural Science Foundation of China under Grant Nos.50978047 and 11332004National Basic Research Program of China under Grant No.2010CB832703
文摘This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-counting fractal dimensions and five representative period parameters of near-fault ground motions from the Chi-Chi and Northridge earthquakes are calculated and compared. Numerical results indicate that the acceleration and velocity time histories of ground motions present the statistical fractal property, and the dominant pulses of near-fault ground motions have a significant influence on their box dimensions and periods. Further, the average box dimension of near-fault impulsive ground motions is smaller, and their irregular degree of wave forms is lower. Moreover, the box dimensions of ground motions reflect their frequency properties to a large extent, and can be regarded as an alternative indicator to represent their frequency content. Finally, the box dimension D of the acceleration histories shows a considerably negative correlation with the mean period T. Meanwhile, the box dimension of the velocity histories Dye is negatively correlated with the characteristic period T and improved characteristic period Tgi.
文摘According to the definition of correlation dimension in fractal theory, this paper presented a method to determine and assess noise part in detected transient signal. Such work is essential to decrease the noise part in the detected signal. It is proved that heart period signal (HPS) is one typical sort of transient chaotic signal. Through experiment and simulation, the analysis of chaotic HPS in the detected signal was done. In the end, we deepen the researches on attractor dimension of HPS for persons who are different in age.
文摘总结了关联维数和K o lm ogorov熵的计算方法,给出详细的计算步骤,并通过对某型发动机在不同状态下关联维数和K o lm ogorov熵的计算和混沌特性分析,提出一种将关联维数和K o lm ogorov熵结合使用的新的故障诊断手段。实验结果表明:由于不同故障的动力学产生机制不同,通常也具有不同的关联维数和K o l-m ogorov熵,故关联维数和K o lm ogorov熵可用于故障的特征提取。
