During transient electromagnetic method （TEM） exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon （a voltage change from positive to negative） caused by the influence of the i...During transient electromagnetic method （TEM） exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon （a voltage change from positive to negative） caused by the influence of the induced polarization （IP） effect, which affects the depth and precision of the TEM detection. The conventional inversion method is inefficient because it is difficult to process the data. In this paper, the Cole-Cole model is adopted to analyze the effect of Dc resistivity, chargeability, time constant, and frequency exponent on the TEM response in an homogeneous half space model. Singular Value Decomposition （SVD） is used to invert the measured TEM data, and the Dc resistivity, chargeability, time constant and frequency exponent were extracted from the measured TEM data in the mine area. The extracted parameters are used for interpreting the detection result as a supplement. This reveals why the TEM data acquired in the area has a low resolution. It was found that the DC resistivity and time constant do not significantly change the results, however, the chargeability and frequency exponent have a significant effect. Because of these influences, the SVD method is more accurate than the conventional method in the apparent resistivity profile. The area of the copper mine is confined accurately based on the SVD inverted data. The conclusion has been verified by drill and is identical to the practical geological situation.展开更多
We designed the window function of the optimal Gabor transform based on the time-frequency rotation property of the fractional Fourier transform. Thus, we obtained the adaptive optimal Gabor transform in the fractiona...We designed the window function of the optimal Gabor transform based on the time-frequency rotation property of the fractional Fourier transform. Thus, we obtained the adaptive optimal Gabor transform in the fractional domain and improved the time-frequency concentration of the Gabor transform. The algorithm first searches for the optimal rotation factor, then performs the p-th FrFT of the signal and, finally, performs time and frequency analysis of the FrFT result. Finally, the algorithm rotates the plane in the fractional domain back to the normal time-frequency plane. This promotes the application of FrFT in the field of high-resolution reservoir prediction. Additionally, we proposed an adaptive search method for the optimal rotation factor using the Parseval principle in the fractional domain, which simplifies the algorithm. We carried out spectrum decomposition of the seismic signal, which showed that the instantaneous frequency slices obtained by the proposed algorithm are superior to the ones obtained by the traditional Gabor transform. The adaptive time frequency analysis is of great significance to seismic signal processing.展开更多
An incrementally nonlinear hypoplastic constitutive model was introduced, which was developed without recourse to the concepts in elastoplasticity theory such as yield surface, plastic potential and the decomposition ...An incrementally nonlinear hypoplastic constitutive model was introduced, which was developed without recourse to the concepts in elastoplasticity theory such as yield surface, plastic potential and the decomposition of the deformation into elastic and plastic parts. Triaxial drained tests on rockfill were conducted on a large scale triaxial apparatus under two types of stress paths, which were the stress paths of constant stress ratio and the complex stress paths with transitional features. Motivated by the effect of stress path, the Gudehus-Bauer hypoplastic model was improved by considering the parameter variations with different ratios of stress increment. Fitting parameter a presents a piecewise linear relationship with cosine of the slope angle θ determined by instantaneous stress path. The improved hypoplastic model can present peak stress increasing and volumetric strain changing from dilatancy to contractancy with the increase of transitional confining pressure σ3t and the decrease of slope angle θ of stress path. Compared with the test data, it is shown that the model is capable of fully considering the effect of stress path on rockfill.展开更多
Using the integral representation of the Jost solution,we deduce some conditions as the kernel functionN(x,y,t)if the Jost solution satisfies the two Lax equations.Then we verify the multi-soliton solution of NLS equa...Using the integral representation of the Jost solution,we deduce some conditions as the kernel functionN(x,y,t)if the Jost solution satisfies the two Lax equations.Then we verify the multi-soliton solution of NLS equationwith non-vanishing boundary conditions if we prove that these conditions can be demonstrated by the GLM equation,which determines the kernel function N(x,y,t)in according to the inverse scattering method.展开更多
An asymmetric fiber （Fabry-Perot, F-P） interferometric cavity with the good linearity and wide dynamic range was successfully designed based on the optical thin film characteristic matrix theory; by adjusting the ma...An asymmetric fiber （Fabry-Perot, F-P） interferometric cavity with the good linearity and wide dynamic range was successfully designed based on the optical thin film characteristic matrix theory; by adjusting the material of two different thin metallic layers, the asymmetric fiber F-P interferometric cavity was fabricated by depositing the multi-layer thin films on the optical fiber＇s end face. The asymmetric F-P cavity has the extensive potential application. In this paper, the demodulation method for the wavelength shift of the fiber Bragg grating （FBG） sensor based on the F-P cavity is demonstrated, and a theoretical formula is obtained. And the experimental results coincide well with the computational results obtained from the theoretical model.展开更多
An element decomposition method with variance strain stabilization(EDM-VSS) is proposed. In the present EDM-VSS, the quadrilateral element is first divided into four sub-triangular cells, and the local strains in sub-...An element decomposition method with variance strain stabilization(EDM-VSS) is proposed. In the present EDM-VSS, the quadrilateral element is first divided into four sub-triangular cells, and the local strains in sub-triangular cells are obtained using linear interpolation function. For each quadrilateral element, the strain of the whole quadrilateral is the weighted average value of the local strains, which means only one integration point is adopted to construct the stiffness matrix. The stabilization item of the stiffness matrix is constructed by variance of the local strains, which can eliminate the instability of the one-point integration formulation and largely increase the accuracy of the element. Compared with conventional full integration quadrilateral element, the EDM-VSS achieves more accurate results and expends much lower computational cost. More importantly, as no mapping or coordinate transformation is involved in the present EDM-VSS, the restriction on the conventional quadrilateral elements can be removed and problem domain can be discretized in more flexible ways. To verify the accuracy and stability of the present formulation, a number of numerical examples are studied to demonstrate the efficiency of the present EDM-VSS.展开更多
The buckling design of micro-films has various potential applications to engineering.The substrate prestrain,interconnector buckling amplitude and critical strain are important parameters for the buckling design.In th...The buckling design of micro-films has various potential applications to engineering.The substrate prestrain,interconnector buckling amplitude and critical strain are important parameters for the buckling design.In the presented analysis,the buckled film shape was described approximately by a trigonometric function and the buckled film amplitude was obtained by minimizing the total strain energy.However,this method only generates the first-order approximate solution for the nonlinear buckling.In the present paper,an asymptotic analysis based on the rigorous nonlinear differential equation for the buckled micro-film deformations is proposed to obtain more accurate relationship of the buckling amplitude and critical strain to prestrain.The obtained results reveal the nonlinear relation and are significant to accurate buckling design of micro-films.展开更多
基金supported by the National Technology R&D Program in the 11th Five year Plan of China(No.2007BAQ00168-1-1)the National Natural Science Foundation of China(No. 41103052/D0309)the Shanxi Province Excellent Graduate Innovation Program(No. 20113038)
文摘During transient electromagnetic method （TEM） exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon （a voltage change from positive to negative） caused by the influence of the induced polarization （IP） effect, which affects the depth and precision of the TEM detection. The conventional inversion method is inefficient because it is difficult to process the data. In this paper, the Cole-Cole model is adopted to analyze the effect of Dc resistivity, chargeability, time constant, and frequency exponent on the TEM response in an homogeneous half space model. Singular Value Decomposition （SVD） is used to invert the measured TEM data, and the Dc resistivity, chargeability, time constant and frequency exponent were extracted from the measured TEM data in the mine area. The extracted parameters are used for interpreting the detection result as a supplement. This reveals why the TEM data acquired in the area has a low resolution. It was found that the DC resistivity and time constant do not significantly change the results, however, the chargeability and frequency exponent have a significant effect. Because of these influences, the SVD method is more accurate than the conventional method in the apparent resistivity profile. The area of the copper mine is confined accurately based on the SVD inverted data. The conclusion has been verified by drill and is identical to the practical geological situation.
基金supported by national natural science foundation of China(No.41274127,41301460,40874066,and 40839905)
文摘We designed the window function of the optimal Gabor transform based on the time-frequency rotation property of the fractional Fourier transform. Thus, we obtained the adaptive optimal Gabor transform in the fractional domain and improved the time-frequency concentration of the Gabor transform. The algorithm first searches for the optimal rotation factor, then performs the p-th FrFT of the signal and, finally, performs time and frequency analysis of the FrFT result. Finally, the algorithm rotates the plane in the fractional domain back to the normal time-frequency plane. This promotes the application of FrFT in the field of high-resolution reservoir prediction. Additionally, we proposed an adaptive search method for the optimal rotation factor using the Parseval principle in the fractional domain, which simplifies the algorithm. We carried out spectrum decomposition of the seismic signal, which showed that the instantaneous frequency slices obtained by the proposed algorithm are superior to the ones obtained by the traditional Gabor transform. The adaptive time frequency analysis is of great significance to seismic signal processing.
基金Projects(50479057, 50639060) supported by the National Natural Science Foundation of China
文摘An incrementally nonlinear hypoplastic constitutive model was introduced, which was developed without recourse to the concepts in elastoplasticity theory such as yield surface, plastic potential and the decomposition of the deformation into elastic and plastic parts. Triaxial drained tests on rockfill were conducted on a large scale triaxial apparatus under two types of stress paths, which were the stress paths of constant stress ratio and the complex stress paths with transitional features. Motivated by the effect of stress path, the Gudehus-Bauer hypoplastic model was improved by considering the parameter variations with different ratios of stress increment. Fitting parameter a presents a piecewise linear relationship with cosine of the slope angle θ determined by instantaneous stress path. The improved hypoplastic model can present peak stress increasing and volumetric strain changing from dilatancy to contractancy with the increase of transitional confining pressure σ3t and the decrease of slope angle θ of stress path. Compared with the test data, it is shown that the model is capable of fully considering the effect of stress path on rockfill.
基金the Huazhong University of Science and Technology under Grant No.0101011110National Natural Science Foundation of China under Grant No.10375041
文摘Using the integral representation of the Jost solution,we deduce some conditions as the kernel functionN(x,y,t)if the Jost solution satisfies the two Lax equations.Then we verify the multi-soliton solution of NLS equationwith non-vanishing boundary conditions if we prove that these conditions can be demonstrated by the GLM equation,which determines the kernel function N(x,y,t)in according to the inverse scattering method.
文摘An asymmetric fiber （Fabry-Perot, F-P） interferometric cavity with the good linearity and wide dynamic range was successfully designed based on the optical thin film characteristic matrix theory; by adjusting the material of two different thin metallic layers, the asymmetric fiber F-P interferometric cavity was fabricated by depositing the multi-layer thin films on the optical fiber＇s end face. The asymmetric F-P cavity has the extensive potential application. In this paper, the demodulation method for the wavelength shift of the fiber Bragg grating （FBG） sensor based on the F-P cavity is demonstrated, and a theoretical formula is obtained. And the experimental results coincide well with the computational results obtained from the theoretical model.
基金supported by the National Natural Science Foundation of China(Grant Nos.11472101 and 61232014)Postdoctoral Science Foundation of China(Grant No.2013M531780)the National Laboratory for Electric Vehicles Foundations
文摘An element decomposition method with variance strain stabilization(EDM-VSS) is proposed. In the present EDM-VSS, the quadrilateral element is first divided into four sub-triangular cells, and the local strains in sub-triangular cells are obtained using linear interpolation function. For each quadrilateral element, the strain of the whole quadrilateral is the weighted average value of the local strains, which means only one integration point is adopted to construct the stiffness matrix. The stabilization item of the stiffness matrix is constructed by variance of the local strains, which can eliminate the instability of the one-point integration formulation and largely increase the accuracy of the element. Compared with conventional full integration quadrilateral element, the EDM-VSS achieves more accurate results and expends much lower computational cost. More importantly, as no mapping or coordinate transformation is involved in the present EDM-VSS, the restriction on the conventional quadrilateral elements can be removed and problem domain can be discretized in more flexible ways. To verify the accuracy and stability of the present formulation, a number of numerical examples are studied to demonstrate the efficiency of the present EDM-VSS.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11002077 and 11072215)
文摘The buckling design of micro-films has various potential applications to engineering.The substrate prestrain,interconnector buckling amplitude and critical strain are important parameters for the buckling design.In the presented analysis,the buckled film shape was described approximately by a trigonometric function and the buckled film amplitude was obtained by minimizing the total strain energy.However,this method only generates the first-order approximate solution for the nonlinear buckling.In the present paper,an asymptotic analysis based on the rigorous nonlinear differential equation for the buckled micro-film deformations is proposed to obtain more accurate relationship of the buckling amplitude and critical strain to prestrain.The obtained results reveal the nonlinear relation and are significant to accurate buckling design of micro-films.
