Numerical calculation for two integral transforms in 2.5-D transient electromagnetic forward is a difficult and key task, namely, the inverse Fourier transform and the inverse Laplace transform. Some effective algorit...Numerical calculation for two integral transforms in 2.5-D transient electromagnetic forward is a difficult and key task, namely, the inverse Fourier transform and the inverse Laplace transform. Some effective algorithms for them were described. Based on the known algorithms in DC resistivity on wave-number distribution and selection, we proposed a principle on how to choose the least wave-number concerning the central-loop transient electromagnetic method. First, observe the behavior of transformation function curve with regard to wave-number in Fourier domain. In the light of its asymptote, ascertain the coverage scope of wave-number. Compared with analytic solution, the least wave-number in Fourier domain can be derived. Furthermore, the Laplace numerical inversion algorithm which needs only a few Laplace variables in pure real domain was also introduced here. The procedure was applied to forward modeling on transient electromagnetic field of a vertical magnetic dipole over uniform half-space to demonstrate them effectiveness and general applicability.展开更多
Waves occurring in cold-rolled plates or sheets can be divided into longitudinal and transverse waves. Classical leveling theories merely solve the problem of longitudinal waves, while no well accepted method can be e...Waves occurring in cold-rolled plates or sheets can be divided into longitudinal and transverse waves. Classical leveling theories merely solve the problem of longitudinal waves, while no well accepted method can be employed for transverse waves. In order to investigate the essential deformation law of leveling for plates with transverse waves, a 2.5-dimensional （2.5- D） analytical approach was proposed. In this model, the plate was transversely divided into some strips with equal width; the strips are considered to be in the state of plane strain and each group of adjacent strips are assumed to be deformation compatible under stress. After calculation, the bending deformation of each strip and the leveling effect of overall plate were obtained by comprehensNe consideration of various strips along with the width. Bending of roller is a main approach to eliminate the transverse waves, which is widely accepted by the industry, but the essential effect of bending of roller on the deformation of plates and the calculation of bending of roller are unknown. According to the 2.5-D analytical model, it can be found that, for plates, it is neutral plane offsetting and middle plane elongation or contraction under inner stress that can effectively improve plate shape. Taking double side waves as an example, the appropriate values of bending of roller were obtained by the 2.5-D analytical model related to different initial unevenness, which was applicable to the current on-line adjusting of bending of roller in rolling industry.展开更多
In this work,we interpreted gravity data to determine the structural characteristics responsible for high-gravity anomalies in Bagodo,North Cameroon.These anomalies had not previously been characterized through a loca...In this work,we interpreted gravity data to determine the structural characteristics responsible for high-gravity anomalies in Bagodo,North Cameroon.These anomalies had not previously been characterized through a local study.Thus,we undertook a regional-residual separation of the gravity anomalies by using the polynomial method.Geophysical signatures of near-surface small-extent geological structures were revealed.To conduct a quantitative interpretation of the gravity anomalies,one profile was drawn on a residual Bouguer anomaly map and then interpreted by spectral analysis,the ideal body solution,and 2.5-dimensional modeling.Our results showed that the intrusive body in the Bagodo area consists of two trapezoidal blocks.The first and second blocks have roofs approximately 7.5 and 14 km deep,respectively,whereas their bases are approximately 17 km deep.These values are in agreement with those obtained by the ideal body solution,which showed two cells with a density contrast of 0.3 g·cm^(−3) in comparison with the surrounding rocks.The density of this body was estimated to be approximately 3 g·cm^(−3).The topography of these rocks showed that they are basaltic rocks that would have cooled in fracture zones as an intrusion.展开更多
基金Project(40344022) supported by the National Natural Science Foundation of China
文摘Numerical calculation for two integral transforms in 2.5-D transient electromagnetic forward is a difficult and key task, namely, the inverse Fourier transform and the inverse Laplace transform. Some effective algorithms for them were described. Based on the known algorithms in DC resistivity on wave-number distribution and selection, we proposed a principle on how to choose the least wave-number concerning the central-loop transient electromagnetic method. First, observe the behavior of transformation function curve with regard to wave-number in Fourier domain. In the light of its asymptote, ascertain the coverage scope of wave-number. Compared with analytic solution, the least wave-number in Fourier domain can be derived. Furthermore, the Laplace numerical inversion algorithm which needs only a few Laplace variables in pure real domain was also introduced here. The procedure was applied to forward modeling on transient electromagnetic field of a vertical magnetic dipole over uniform half-space to demonstrate them effectiveness and general applicability.
基金Sponsored by National Science and Technology Major Project of China(2012ZX04012011)National Natural Science Foundation of China(51375306)
文摘Waves occurring in cold-rolled plates or sheets can be divided into longitudinal and transverse waves. Classical leveling theories merely solve the problem of longitudinal waves, while no well accepted method can be employed for transverse waves. In order to investigate the essential deformation law of leveling for plates with transverse waves, a 2.5-dimensional （2.5- D） analytical approach was proposed. In this model, the plate was transversely divided into some strips with equal width; the strips are considered to be in the state of plane strain and each group of adjacent strips are assumed to be deformation compatible under stress. After calculation, the bending deformation of each strip and the leveling effect of overall plate were obtained by comprehensNe consideration of various strips along with the width. Bending of roller is a main approach to eliminate the transverse waves, which is widely accepted by the industry, but the essential effect of bending of roller on the deformation of plates and the calculation of bending of roller are unknown. According to the 2.5-D analytical model, it can be found that, for plates, it is neutral plane offsetting and middle plane elongation or contraction under inner stress that can effectively improve plate shape. Taking double side waves as an example, the appropriate values of bending of roller were obtained by the 2.5-D analytical model related to different initial unevenness, which was applicable to the current on-line adjusting of bending of roller in rolling industry.
文摘In this work,we interpreted gravity data to determine the structural characteristics responsible for high-gravity anomalies in Bagodo,North Cameroon.These anomalies had not previously been characterized through a local study.Thus,we undertook a regional-residual separation of the gravity anomalies by using the polynomial method.Geophysical signatures of near-surface small-extent geological structures were revealed.To conduct a quantitative interpretation of the gravity anomalies,one profile was drawn on a residual Bouguer anomaly map and then interpreted by spectral analysis,the ideal body solution,and 2.5-dimensional modeling.Our results showed that the intrusive body in the Bagodo area consists of two trapezoidal blocks.The first and second blocks have roofs approximately 7.5 and 14 km deep,respectively,whereas their bases are approximately 17 km deep.These values are in agreement with those obtained by the ideal body solution,which showed two cells with a density contrast of 0.3 g·cm^(−3) in comparison with the surrounding rocks.The density of this body was estimated to be approximately 3 g·cm^(−3).The topography of these rocks showed that they are basaltic rocks that would have cooled in fracture zones as an intrusion.
