To address the key scientific challenge of monitoring the dynamic fracturing of surrounding rock in deep roadways,this study systematically investigates the quantitative relationship between stress and charge signals ...To address the key scientific challenge of monitoring the dynamic fracturing of surrounding rock in deep roadways,this study systematically investigates the quantitative relationship between stress and charge signals during coal mass loading.By integrating innovative analytical approaches,introducing quantitative evaluation indices,and developing a charge–stress inversion model,and incorporating underground monitoring practices,significant progress has been achieved in elucidating the correlation between stress variations and charge signals throughout the entire coal mass fracturing process.First,in the field of stress–charge correlation analysis,empirical mode decomposition(EMD)was combined with wavelet coherence analysis for the first time,enabling the removal of slow-varying stress trends while retaining high-frequency fluctuations.This approach allowed for the quantitative characterization of the evolution of coherence between stress variations and charge fluctuations across multiple time scales.Second,coherence skewness and the proportion of high-coherence intervals were innovatively introduced to examine the influence of time scale selection on correlation results.On this basis,a criterion for determining the near-optimal observation scale of charge signals was proposed,providing a quantitative reference for time scale selection in similar signal analyses.Finally,by correlating charge signals with coal damage factors and stress states,a charge-based damage evolution equation was established to achieve effective stress inversion.Combined with in situ monitoring of stress and charge in roadway surrounding rock,this approach revealed the correlation characteristics of stress and charge intensity responses during the dynamic fracturing process.The results indicate,first,that charge signals are not significantly correlated with the absolute stress level of coal but are directly associated with stress variations following coal damage and failure,with the amplitude of charge fluctuations increasing alongside stress fluctuations.Second,coherence between stress and charge signals varies markedly across time scales,with excessively small or large scales leading to distortion,and the scale corresponding to the peak proportion of intervals with coherence>0.8 was identified as the near-optimal observation scale.Third,charge signals can effectively characterize coal damage factors,and the established damage evolution equation can effectively invert stress variation trends.Fourth,in underground roadways,zones of dynamic fracturing in surrounding rock are commonly located in areas where stress concentration overlaps with regions of high charge intensity,further confirming the strong consistency between charge and stress variations.These findings improve the theoretical framework of charge signal responses in loaded coal and provide a scientific basis for precise“stress-charge”monitoring of dynamic disasters,offering practical potential for engineering applications.展开更多
Building segmentation from high-resolution synthetic aperture radar (SAR) images has always been one of the important research issues. Due to the existence of speckle noise and multipath effect, the pixel values chang...Building segmentation from high-resolution synthetic aperture radar (SAR) images has always been one of the important research issues. Due to the existence of speckle noise and multipath effect, the pixel values change drastically, causing the large intensity differences in pixels of building areas. Moreover, the geometric structure of buildings can cause strong scattering spots, which brings difficulties to the segmentation and extraction of buildings. To solve of these problems, this paper presents a coherence-coefficient-based Markov random field (CCMRF) approach for building segmentation from high-resolution SAR images. The method introduces the coherence coefficient of interferometric synthetic aperture radar (InSAR) into the neighborhood energy based on traditional Markov random field (MRF), which makes interferometric and spatial contextual information more fully used in SAR image segmentation. According to the Hammersley-Clifford theorem, the problem of maximum a posteriori (MAP) for image segmentation is transformed into the solution of minimizing the sum of likelihood energy and neighborhood energy. Finally, the iterative condition model (ICM) is used to find the optimal solution. The experimental results demonstrate that the proposed method can segment SAR building effectively and obtain more accurate results than the traditional MRF method and K-means clustering.展开更多
Through theoretical analysis of reliability and simulation analysis of dispersivi of d a/ d N based on Monte Carlo method, the distribution function of n and c was set up. Meanwhile, the distribution of critical ...Through theoretical analysis of reliability and simulation analysis of dispersivi of d a/ d N based on Monte Carlo method, the distribution function of n and c was set up. Meanwhile, the distribution of critical opening displacement(COD)δ c was defined by the use of coherent coefficient method, and the probabilistic model of defects assessment of military special vessel was built. Thereby the theoretical and practical fundamental research on evaluation of reliability of military high pressure vessels was carried out.展开更多
A simplified multisupport response spectrum method is presented.The structural response is a sum of two components of a structure with a first natural period less than 2 s.The first component is the pseudostatic respo...A simplified multisupport response spectrum method is presented.The structural response is a sum of two components of a structure with a first natural period less than 2 s.The first component is the pseudostatic response caused by the inconsistent motions of the structural supports,and the second is the structural dynamic response to ground motion accelerations.This method is formally consistent with the classical response spectrum method,and the effects of multisupport excitation are considered for any modal response spectrum or modal superposition.If the seismic inputs at each support are the same,the support displacements caused by the pseudostatic response become rigid body displacements.The response spectrum in the case of multisupport excitations then reduces to that for uniform excitations.In other words,this multisupport response spectrum method is a modification and extension of the existing response spectrum method under uniform excitation.Moreover,most of the coherency coefficients in this formulation are simplified by approximating the ground motion excitation as white noise.The results indicate that this simplification can reduce the calculation time while maintaining accuracy.Furthermore,the internal forces obtained by the multisupport response spectrum method are compared with those produced by the traditional response spectrum method in two case studies of existing long-span structures.Because the effects of inconsistent support displacements are not considered in the traditional response spectrum method,the values of internal forces near the supports are underestimated.These regions are important potential failure points and deserve special attention in the seismic design of reticulated structures.展开更多
The space-time ladder theory reveals that the formation of electronic tornadoes,or the formation of electronic dissipative structures,to be precise,the enhancement of electronic Energy Qi field is the basis of superco...The space-time ladder theory reveals that the formation of electronic tornadoes,or the formation of electronic dissipative structures,to be precise,the enhancement of electronic Energy Qi field is the basis of superconductivity.The surrounding area of the electronic tornado is expanding,which is the basis of the Meissner effect,and the center is contracting,which is the basis of the pinning force.When the attractive force of the Energy Qi field is greater than the Coulomb repulsive force,the electrons form a Cooper pair and release dark energy into virtual space-time.When the dark energy increases to a certain extent,the virtual space-time frees the Cooper pair and forms an electron-virtual space-time wave,which fluctuates freely in the superconducting material,which is the basis for the superconducting resistance to be zero.This is similar to the principle of a hot air balloon.The virtual space-time is hot air and the electron pair is a hot air balloon device.Conductor electrons are free and easy to emit dark energy,resulting in insufficient dark energy,and it is not easy to form electron-pair virtual space-time waves,so the superconducting critical temperature is very low.This is because the emission coefficient of the conductor is too high.Insulator electrons are not easy to emit dark energy and easily form electron-pair virtual space-time waves.Therefore,the superconducting critical temperature is slightly higher because of the low emission coefficient of the insulator.The solution of the Qi-space-time wave equation,that is,the coherence coefficient,is an important factor in superconductivity.In addition,the conditions under which tornadoes form are also an important basis for superconductivity.Finally,it is emphasized that the coherence coefficient and prevention of dark energy emission are the two most important elements for preparing superconducting materials.展开更多
基金supported by the Research Fund of the National Natural Science Foundation of China(No.52374205)the Fundamental Research Project of the Educational Department of Liaoning Province(No.JYTMS20230793)the Research Fund of the State Key Laboratory of Coal Resources and Safe Mining,CUMT(No.YJY-XD-2024-A-016).
文摘To address the key scientific challenge of monitoring the dynamic fracturing of surrounding rock in deep roadways,this study systematically investigates the quantitative relationship between stress and charge signals during coal mass loading.By integrating innovative analytical approaches,introducing quantitative evaluation indices,and developing a charge–stress inversion model,and incorporating underground monitoring practices,significant progress has been achieved in elucidating the correlation between stress variations and charge signals throughout the entire coal mass fracturing process.First,in the field of stress–charge correlation analysis,empirical mode decomposition(EMD)was combined with wavelet coherence analysis for the first time,enabling the removal of slow-varying stress trends while retaining high-frequency fluctuations.This approach allowed for the quantitative characterization of the evolution of coherence between stress variations and charge fluctuations across multiple time scales.Second,coherence skewness and the proportion of high-coherence intervals were innovatively introduced to examine the influence of time scale selection on correlation results.On this basis,a criterion for determining the near-optimal observation scale of charge signals was proposed,providing a quantitative reference for time scale selection in similar signal analyses.Finally,by correlating charge signals with coal damage factors and stress states,a charge-based damage evolution equation was established to achieve effective stress inversion.Combined with in situ monitoring of stress and charge in roadway surrounding rock,this approach revealed the correlation characteristics of stress and charge intensity responses during the dynamic fracturing process.The results indicate,first,that charge signals are not significantly correlated with the absolute stress level of coal but are directly associated with stress variations following coal damage and failure,with the amplitude of charge fluctuations increasing alongside stress fluctuations.Second,coherence between stress and charge signals varies markedly across time scales,with excessively small or large scales leading to distortion,and the scale corresponding to the peak proportion of intervals with coherence>0.8 was identified as the near-optimal observation scale.Third,charge signals can effectively characterize coal damage factors,and the established damage evolution equation can effectively invert stress variation trends.Fourth,in underground roadways,zones of dynamic fracturing in surrounding rock are commonly located in areas where stress concentration overlaps with regions of high charge intensity,further confirming the strong consistency between charge and stress variations.These findings improve the theoretical framework of charge signal responses in loaded coal and provide a scientific basis for precise“stress-charge”monitoring of dynamic disasters,offering practical potential for engineering applications.
文摘Building segmentation from high-resolution synthetic aperture radar (SAR) images has always been one of the important research issues. Due to the existence of speckle noise and multipath effect, the pixel values change drastically, causing the large intensity differences in pixels of building areas. Moreover, the geometric structure of buildings can cause strong scattering spots, which brings difficulties to the segmentation and extraction of buildings. To solve of these problems, this paper presents a coherence-coefficient-based Markov random field (CCMRF) approach for building segmentation from high-resolution SAR images. The method introduces the coherence coefficient of interferometric synthetic aperture radar (InSAR) into the neighborhood energy based on traditional Markov random field (MRF), which makes interferometric and spatial contextual information more fully used in SAR image segmentation. According to the Hammersley-Clifford theorem, the problem of maximum a posteriori (MAP) for image segmentation is transformed into the solution of minimizing the sum of likelihood energy and neighborhood energy. Finally, the iterative condition model (ICM) is used to find the optimal solution. The experimental results demonstrate that the proposed method can segment SAR building effectively and obtain more accurate results than the traditional MRF method and K-means clustering.
文摘Through theoretical analysis of reliability and simulation analysis of dispersivi of d a/ d N based on Monte Carlo method, the distribution function of n and c was set up. Meanwhile, the distribution of critical opening displacement(COD)δ c was defined by the use of coherent coefficient method, and the probabilistic model of defects assessment of military special vessel was built. Thereby the theoretical and practical fundamental research on evaluation of reliability of military high pressure vessels was carried out.
基金Major Program of National Science Foundation of China Under Grant No.90715005Program for New Century Excellent Talents in University Under Grant No. NCET-07-0186Doctoral Fund of Ministry of Education of China Under Grant No.200802860007
文摘A simplified multisupport response spectrum method is presented.The structural response is a sum of two components of a structure with a first natural period less than 2 s.The first component is the pseudostatic response caused by the inconsistent motions of the structural supports,and the second is the structural dynamic response to ground motion accelerations.This method is formally consistent with the classical response spectrum method,and the effects of multisupport excitation are considered for any modal response spectrum or modal superposition.If the seismic inputs at each support are the same,the support displacements caused by the pseudostatic response become rigid body displacements.The response spectrum in the case of multisupport excitations then reduces to that for uniform excitations.In other words,this multisupport response spectrum method is a modification and extension of the existing response spectrum method under uniform excitation.Moreover,most of the coherency coefficients in this formulation are simplified by approximating the ground motion excitation as white noise.The results indicate that this simplification can reduce the calculation time while maintaining accuracy.Furthermore,the internal forces obtained by the multisupport response spectrum method are compared with those produced by the traditional response spectrum method in two case studies of existing long-span structures.Because the effects of inconsistent support displacements are not considered in the traditional response spectrum method,the values of internal forces near the supports are underestimated.These regions are important potential failure points and deserve special attention in the seismic design of reticulated structures.
文摘The space-time ladder theory reveals that the formation of electronic tornadoes,or the formation of electronic dissipative structures,to be precise,the enhancement of electronic Energy Qi field is the basis of superconductivity.The surrounding area of the electronic tornado is expanding,which is the basis of the Meissner effect,and the center is contracting,which is the basis of the pinning force.When the attractive force of the Energy Qi field is greater than the Coulomb repulsive force,the electrons form a Cooper pair and release dark energy into virtual space-time.When the dark energy increases to a certain extent,the virtual space-time frees the Cooper pair and forms an electron-virtual space-time wave,which fluctuates freely in the superconducting material,which is the basis for the superconducting resistance to be zero.This is similar to the principle of a hot air balloon.The virtual space-time is hot air and the electron pair is a hot air balloon device.Conductor electrons are free and easy to emit dark energy,resulting in insufficient dark energy,and it is not easy to form electron-pair virtual space-time waves,so the superconducting critical temperature is very low.This is because the emission coefficient of the conductor is too high.Insulator electrons are not easy to emit dark energy and easily form electron-pair virtual space-time waves.Therefore,the superconducting critical temperature is slightly higher because of the low emission coefficient of the insulator.The solution of the Qi-space-time wave equation,that is,the coherence coefficient,is an important factor in superconductivity.In addition,the conditions under which tornadoes form are also an important basis for superconductivity.Finally,it is emphasized that the coherence coefficient and prevention of dark energy emission are the two most important elements for preparing superconducting materials.
