The paper proposes a new multiple-factor clustering method(NMFCM)with consideration of both box fractal dimension(BFD)and orientation of joints.This method assumes that the BFDs of different clusters were uneven,and c...The paper proposes a new multiple-factor clustering method(NMFCM)with consideration of both box fractal dimension(BFD)and orientation of joints.This method assumes that the BFDs of different clusters were uneven,and clustering was performed by redistributing the joints near the boundaries of clusters on a polar map to maximize an index for estimating the difference of the BFD(DBFD).Three main aspects were studied to develop the NMFCM.First,procedures of the NMFCM and reasonableness of assumptions were illustrated.Second,main factors affecting the NMFCM were investigated by numerical simulations with disk joint models.Finally,two different sections of a rock slope were studied to verify the practicability of the NMFCM.The results demonstrated that:(1)The NMFCM was practical and could effectively alleviate the problem of hard boundary during clustering;(2)The DBFD tended to increase after the improvement of clustering accuracy;(3)The improvement degree of the NMFCM clustering accuracy was mainly influenced by three parameters,namely,the number of clusters,number of redistributed joints,and total number of joints;and(4)The accuracy rate of clustering could be effectively improved by the NMFCM.展开更多
Based on the judgement of fractional Br ow nian motion, this paper analyzes the radial rotating error of a precision rotor. The results indicate that the rotating error motion of the precision rot or is characterized...Based on the judgement of fractional Br ow nian motion, this paper analyzes the radial rotating error of a precision rotor. The results indicate that the rotating error motion of the precision rot or is characterized by basic fractional Brownian motions, i.e. randomicity, non -sequencity, and self-simulation insinuation to some extent. Also, this paper calculates the fractal box counting dimension of radial rotating error and judges that the rotor error motion is of stability, indicating that the motion range of the future track of the axes is relatively stable.展开更多
原始精细的路面谱是研究车辆与路面耦合的重要基础,对车辆的通过性和噪声、振动及不平顺性NVH(noise,vibration and harshness)分析有重要的应用价值。为了构建与原始路面相同或相近的路面谱,利用非接触式激光路面不平度仪测量沥青路面...原始精细的路面谱是研究车辆与路面耦合的重要基础,对车辆的通过性和噪声、振动及不平顺性NVH(noise,vibration and harshness)分析有重要的应用价值。为了构建与原始路面相同或相近的路面谱,利用非接触式激光路面不平度仪测量沥青路面、水泥路面、比利时路面和砂石路面的三维路面不平度;基于分形理论,采用迭代函数法重构这四种路面谱;结合路面不平度的统计特性评价指标和分形维数对四种路面的原始谱和重构谱进行评价。研究结果表明:重构前、后路面谱的平均值、标准差、峰度系数以及分形维数变化范围在±5%以内,除水泥路面的偏态系数变化范围均在±9%以内,重构路面谱与原始谱具有一致性;重构路面谱保持了原始路面的结构特性,并具有路面的细微结构。展开更多
A new multi-scale numerical model is presented using the fractal theory and adopting FEM to simulate the failure of concrete.The relation between the fractal box dimension in large scale and the damage to concrete in ...A new multi-scale numerical model is presented using the fractal theory and adopting FEM to simulate the failure of concrete.The relation between the fractal box dimension in large scale and the damage to concrete in small scale is deduced.And the evolutionary process of elastic modulus and strength in small scale is given.Consequently,the multi-scale numerical model is proposed to describe the constitutive relation of concrete between small scale and large scale.A two-dimensional static analysis of a concrete block is performed by using this model and the calculation result is discussed.The propagation of cracks of the concrete block is also studied.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.41972264 and 52078093)Liaoning Revitalization Talents Program,China(Grant No.XLYC1905015)。
文摘The paper proposes a new multiple-factor clustering method(NMFCM)with consideration of both box fractal dimension(BFD)and orientation of joints.This method assumes that the BFDs of different clusters were uneven,and clustering was performed by redistributing the joints near the boundaries of clusters on a polar map to maximize an index for estimating the difference of the BFD(DBFD).Three main aspects were studied to develop the NMFCM.First,procedures of the NMFCM and reasonableness of assumptions were illustrated.Second,main factors affecting the NMFCM were investigated by numerical simulations with disk joint models.Finally,two different sections of a rock slope were studied to verify the practicability of the NMFCM.The results demonstrated that:(1)The NMFCM was practical and could effectively alleviate the problem of hard boundary during clustering;(2)The DBFD tended to increase after the improvement of clustering accuracy;(3)The improvement degree of the NMFCM clustering accuracy was mainly influenced by three parameters,namely,the number of clusters,number of redistributed joints,and total number of joints;and(4)The accuracy rate of clustering could be effectively improved by the NMFCM.
文摘Based on the judgement of fractional Br ow nian motion, this paper analyzes the radial rotating error of a precision rotor. The results indicate that the rotating error motion of the precision rot or is characterized by basic fractional Brownian motions, i.e. randomicity, non -sequencity, and self-simulation insinuation to some extent. Also, this paper calculates the fractal box counting dimension of radial rotating error and judges that the rotor error motion is of stability, indicating that the motion range of the future track of the axes is relatively stable.
文摘原始精细的路面谱是研究车辆与路面耦合的重要基础,对车辆的通过性和噪声、振动及不平顺性NVH(noise,vibration and harshness)分析有重要的应用价值。为了构建与原始路面相同或相近的路面谱,利用非接触式激光路面不平度仪测量沥青路面、水泥路面、比利时路面和砂石路面的三维路面不平度;基于分形理论,采用迭代函数法重构这四种路面谱;结合路面不平度的统计特性评价指标和分形维数对四种路面的原始谱和重构谱进行评价。研究结果表明:重构前、后路面谱的平均值、标准差、峰度系数以及分形维数变化范围在±5%以内,除水泥路面的偏态系数变化范围均在±9%以内,重构路面谱与原始谱具有一致性;重构路面谱保持了原始路面的结构特性,并具有路面的细微结构。
基金supported by the National Natural Science Foundation of China(Nos.51109029,51178081,51138001 and51009020)the China Postdoctoral Science Foundation(No.20110491535)
文摘A new multi-scale numerical model is presented using the fractal theory and adopting FEM to simulate the failure of concrete.The relation between the fractal box dimension in large scale and the damage to concrete in small scale is deduced.And the evolutionary process of elastic modulus and strength in small scale is given.Consequently,the multi-scale numerical model is proposed to describe the constitutive relation of concrete between small scale and large scale.A two-dimensional static analysis of a concrete block is performed by using this model and the calculation result is discussed.The propagation of cracks of the concrete block is also studied.
