We introduce the Thomsen anisotropic parameters into the approximate linear reflection coefficient equation for P-SV wave in weakly anisotropic HTI media. From this we get a new, more effective, and practical reflecti...We introduce the Thomsen anisotropic parameters into the approximate linear reflection coefficient equation for P-SV wave in weakly anisotropic HTI media. From this we get a new, more effective, and practical reflection coefficient equation. We performed forward modeling to AVO attributes, obtaining excellent results. The combined AVO attribute analysis of PP and PS reflection data can greatly reduce ambiguity, obtain better petrophysical parameters, and improve parameter accuracy.展开更多
We experimentally studied the effect of crack aperture on P-wave velocity, amplitude, anisotropy and dispersion. Experimental models were constructed based on Hudson＇s theory. Six crack models were embedded with equa...We experimentally studied the effect of crack aperture on P-wave velocity, amplitude, anisotropy and dispersion. Experimental models were constructed based on Hudson＇s theory. Six crack models were embedded with equal-radius penny-shaped crack inclusions in each layer. The P-wave velocity and amplitude were measured parallel and perpendicular to the layers of cracks at frequencies of 0.1 MHz to 1 MHz. The experiments show that as the crack aperture increases from 0.l mm to 0.34 mm, the amplitude of the P-waves parallel to the crack layers decreases linearly with increasing frequency and the P-wave velocity dispersion varies from 1.5% to 2.1%, whereas the amplitude of the P-wave perpendicular to the crack layers decreases quadratically with increasing frequency and the velocity dispersion varies from 1.9% to 4.7%. The variation in the velocity dispersion parallel and perpendicular to the cracks intensifies the anisotropy dispersion of the P-waves in the crack models （6.7% to 83%）. The P-wave dispersion strongly depends on the scattering characteristics of the crack apertures.展开更多
Wave velocities in haloanhydrites are difficult to determine and significantly depend on the mineralogy. We used petrophysical parameters to study the wave velocity in haloanhydrites in the Amur Darya Basin and constr...Wave velocities in haloanhydrites are difficult to determine and significantly depend on the mineralogy. We used petrophysical parameters to study the wave velocity in haloanhydrites in the Amur Darya Basin and constructed a template of the relation between haloanhydrite mineralogy （anhydrite, salt, mudstone, and pore water） and wave velocities. We used the relation between the P-wave rnoduli ratio and porosity as constraint and constructed a graphical model （petrophysical template） for the relation between wave velocity, mineral content and porosity. We tested the graphical model using rock core and well logging data.展开更多
Laboratory tests were performed on Toyoura sand specimens to investigate the relationship between degree of saturation Sr, B-value and P-wave velocity Vp. Different types of pore water （de-aired water or tap water） ...Laboratory tests were performed on Toyoura sand specimens to investigate the relationship between degree of saturation Sr, B-value and P-wave velocity Vp. Different types of pore water （de-aired water or tap water） and pore gas （air or CO2） as well as different magnitudes of back pressure were used to achieve different Sr （or B-value）. The measured relationship between B-value and Vp was not consistent with the theoretical prediction. The measurement shows that the Vp value in the specimen flushed with de-aired water is independent of B-value （or St） and is always around the one in fully saturated condition. However, the Vp value in the specimen flushed with tap water increases with B-value, but the shape of the relationship between Vp and B-value is quite different from the theoretical prediction. The possible explanation for the discrepancy between laboratory measurement and theoretical prediction lies in that the air exists in the water as air bubbles and therefore the pore fluid （air-water mixture） is heterogeneous instead of homogenous assumed in the theoretical prediction.展开更多
Polarity reversals may occur to transmitted P waves if the incidence angle is greater than the critical incidence angle. We analyze the characteristics of reflection and transmission coefficients under the condition o...Polarity reversals may occur to transmitted P waves if the incidence angle is greater than the critical incidence angle. We analyze the characteristics of reflection and transmission coefficients under the condition of wide incidence angle based on Zoeppritz equations. We find that for specific conditions, as the incidence angle increases, the characteristic curve of the transmitted P-wave coefficient enters the third quadrant from the first quadrant through the origin, which produces a transition in the transmitted P wave and the corresponding coefficient experiences polarity reversal. We derive the incidence angle when the transmitted P-wave coefficient is zero and verify that it equals zero by using finite-difference forward modeling for a single-interface model. We replace the water in the model reservoir by gas and see that the reservoir P-wave velocity and density decrease dramatically. By analyzing the synthetic seismogram of the transmitted P wave in the single-interface model, we show that the gas-saturated reservoir is responsible for polarity reversal.展开更多
Background P-wave dispersion （PWD）, a measure of heterogeneity of atrial refractoriness, is defined as the difference between the maximum and minimum P-wave duration. In patients with severe aortic stenosis （AS）, ...Background P-wave dispersion （PWD）, a measure of heterogeneity of atrial refractoriness, is defined as the difference between the maximum and minimum P-wave duration. In patients with severe aortic stenosis （AS）, P-wave duration and PWD were shown to be increased, indicating atrial electrical remodeling. However, the effect of transcatheter aortic valve replacement （TAVR） on P-wave morphology has not been established yet. The aim of this study is to assess the short and long-term effects of TAVR with two types of bioprosthetic valves on P-wave duration and PWD in association with left atrial （LA） size. Methods Fifty-two （36 female） eligible patients in sinus rhythm who underwent transfemoral TAVR between June 01, 2012 and July 31, 2014 with either a Medtronic CoreValve （MCV） （n = 32） or an Edwards SAPIEN XT Valve （n = 20） were enrolled. Standard 12-lead electrocardiogram and echocardiographic evaluations were per- formed pre-procedurally, post-TAVR day one and 6 months post-TAVR. P-wave duration and PWD were measured and correlation analyses with echocardiographic variables were performed. Results P-wave duration and PWD were significantly decreased on post-TAVR day one （P 〈 0.05）. They continued to decrease during the six month follow-up period, but were not significantly different from short-term values （P 〉 0.05）. The decrease of LA diameter was found significant at the sixth-months of follow-up （P 〈 0.05）. These changes were independent from the types of bioprosthetic valves implanted （P 〉 0.05）. A positive correlation was detected between minimum P-wave duration and maximum aortic valve gradients at post-TAVR day one （r = 0.297, P = 0.032）. Conclusions P-wave duration and PWD were significantly reduced early after TAVR indicating early reverse atrial electrical remodeling. Moreover, structural reverse remodeling of atrium was detected at the 6-months of follow-up. The effects of two types of bioprosthetic valves on atrial remodeling were similar.展开更多
In recent years, long-offset exploration has been widely used, especially on marine seismic surveys. Conventional AVO analysis is insufficient for long-offset seismic data. To widen the application range of AVO analys...In recent years, long-offset exploration has been widely used, especially on marine seismic surveys. Conventional AVO analysis is insufficient for long-offset seismic data. To widen the application range of AVO analysis, we present a new P-wave reflection coefficient approximation applicable to long-offset data. Our result is similar to the well known Shuey formula which can be treated as an approximation to our results for short-offset seismic data.展开更多
The indirect boundary element method (IBEM) is used to study the surface motion of an alluvial valley in layered half-space for incident plane P-waves based on Wolf’s theory. Firstly, the free field response can be s...The indirect boundary element method (IBEM) is used to study the surface motion of an alluvial valley in layered half-space for incident plane P-waves based on Wolf’s theory. Firstly, the free field response can be solved by the direct stiffness method, and the scattering wave response is calculated by Green’s functions of distributed loads acting on inclined lines in a layered half-space. The method is verified by comparing its results with literature and numerical analyses are performed by taking the amplification of incident plane P-waves by an alluvial valley in one soil layer resting on bedrock as an example. The results show that there exist distinct differences between the wave amplification by an alluvial valley embedded in layered half-space and that in homogeneous half-space and there is interaction between the valley and the soil layer. The amplitudes are relatively large when incident frequencies are close to the soil layer’s resonant frequencies.展开更多
To revise P-wave velocity and thickness of the hydrate layer in the Shenhu area of the South China Sea, acoustic and resistivity logging curves are reanalyzed. The waterlogging phenomenon is found in the shallow sedim...To revise P-wave velocity and thickness of the hydrate layer in the Shenhu area of the South China Sea, acoustic and resistivity logging curves are reanalyzed. The waterlogging phenomenon is found in the shallow sediments of five drilling wells, which causes P-wave velocity to approximate the propagation velocity of sea water(about 1500 m s-1). This also affects the identification of the hydrate layer and results in the underestimate of its thickness. In addition, because there could be about a 5 m thick velocity ramp above or below the hydrate layer as interpreted by acoustic and resistivity logging curves, the recalibrated thickness of this layer is less than the original estimated thickness. The recalibrated P-wave velocity of the hydrate layer is also higher than the original estimated velocity. For the drilling well with a relatively thin hydrate layer, the velocity ramp plays a more important role in identifying and determining the thickness of the layer.展开更多
Combining two Bose-Einstein condensates(BECs)may result in a miscible or immiscible mixture.In this study,we investigate the miscibility-immiscibility transition of binary BEC mixture trapped in an isotropic harmonic ...Combining two Bose-Einstein condensates(BECs)may result in a miscible or immiscible mixture.In this study,we investigate the miscibility-immiscibility transition of binary BEC mixture trapped in an isotropic harmonic potential,with both inter-species s-wave and p-wave scattering interaction included.The mean-field Gross-Pitaevskii equations with p-wave interaction term are numerically solved to obtain the ground-state phase diagram.Due to the pwave interaction competing with isotropic s-wave interaction,the spatial density profile of binary BEC mixtures transforming from immiscible phase to miscible phase is observed.The p-wave interaction caused miscibility can be observed in current experiments of Bose-Bose mixture tuned near a p-wave Feshbach resonance.展开更多
The Josephson currents in s-wave superconductor/ferromagnet insulator/p-wave superconductor（s/FI/p） junctions are calculated as a function of temperature and the phase taking into account the roughness scattering ef...The Josephson currents in s-wave superconductor/ferromagnet insulator/p-wave superconductor（s/FI/p） junctions are calculated as a function of temperature and the phase taking into account the roughness scattering effect at interface. The phase dependence of the Josephson current I （φ） between s-wave and px-wave superconductor is predicted to be sin（2φ）. The ferromagnet scattering effect, the barrier strength, and the roughness strength at interface suppress the dc currents in s/FI/p junction.展开更多
基金the National "973" Project (No.2007CB209603) the "863" Project (No.2006AA06Z108)
文摘We introduce the Thomsen anisotropic parameters into the approximate linear reflection coefficient equation for P-SV wave in weakly anisotropic HTI media. From this we get a new, more effective, and practical reflection coefficient equation. We performed forward modeling to AVO attributes, obtaining excellent results. The combined AVO attribute analysis of PP and PS reflection data can greatly reduce ambiguity, obtain better petrophysical parameters, and improve parameter accuracy.
基金supported by the Major National Project Program (No.2011ZX05007-006)
文摘We experimentally studied the effect of crack aperture on P-wave velocity, amplitude, anisotropy and dispersion. Experimental models were constructed based on Hudson＇s theory. Six crack models were embedded with equal-radius penny-shaped crack inclusions in each layer. The P-wave velocity and amplitude were measured parallel and perpendicular to the layers of cracks at frequencies of 0.1 MHz to 1 MHz. The experiments show that as the crack aperture increases from 0.l mm to 0.34 mm, the amplitude of the P-waves parallel to the crack layers decreases linearly with increasing frequency and the P-wave velocity dispersion varies from 1.5% to 2.1%, whereas the amplitude of the P-wave perpendicular to the crack layers decreases quadratically with increasing frequency and the velocity dispersion varies from 1.9% to 4.7%. The variation in the velocity dispersion parallel and perpendicular to the cracks intensifies the anisotropy dispersion of the P-waves in the crack models （6.7% to 83%）. The P-wave dispersion strongly depends on the scattering characteristics of the crack apertures.
基金supported by the National Major Scientific and Technological Special Project(No.2011ZX05029-003)the project of the Research Institute of Petroleum Exploration&Development(No.2012Y-058)
文摘Wave velocities in haloanhydrites are difficult to determine and significantly depend on the mineralogy. We used petrophysical parameters to study the wave velocity in haloanhydrites in the Amur Darya Basin and constructed a template of the relation between haloanhydrite mineralogy （anhydrite, salt, mudstone, and pore water） and wave velocities. We used the relation between the P-wave rnoduli ratio and porosity as constraint and constructed a graphical model （petrophysical template） for the relation between wave velocity, mineral content and porosity. We tested the graphical model using rock core and well logging data.
基金Foundation item： Project（2012CB719803） supported by the National Basic Research Program of China Project（201011159098） supported by the Seed Funding for Basic Research Scheme from The University of Hong Kong, China
文摘Laboratory tests were performed on Toyoura sand specimens to investigate the relationship between degree of saturation Sr, B-value and P-wave velocity Vp. Different types of pore water （de-aired water or tap water） and pore gas （air or CO2） as well as different magnitudes of back pressure were used to achieve different Sr （or B-value）. The measured relationship between B-value and Vp was not consistent with the theoretical prediction. The measurement shows that the Vp value in the specimen flushed with de-aired water is independent of B-value （or St） and is always around the one in fully saturated condition. However, the Vp value in the specimen flushed with tap water increases with B-value, but the shape of the relationship between Vp and B-value is quite different from the theoretical prediction. The possible explanation for the discrepancy between laboratory measurement and theoretical prediction lies in that the air exists in the water as air bubbles and therefore the pore fluid （air-water mixture） is heterogeneous instead of homogenous assumed in the theoretical prediction.
基金the National Natural Science Foundation of China(No.41374123)
文摘Polarity reversals may occur to transmitted P waves if the incidence angle is greater than the critical incidence angle. We analyze the characteristics of reflection and transmission coefficients under the condition of wide incidence angle based on Zoeppritz equations. We find that for specific conditions, as the incidence angle increases, the characteristic curve of the transmitted P-wave coefficient enters the third quadrant from the first quadrant through the origin, which produces a transition in the transmitted P wave and the corresponding coefficient experiences polarity reversal. We derive the incidence angle when the transmitted P-wave coefficient is zero and verify that it equals zero by using finite-difference forward modeling for a single-interface model. We replace the water in the model reservoir by gas and see that the reservoir P-wave velocity and density decrease dramatically. By analyzing the synthetic seismogram of the transmitted P wave in the single-interface model, we show that the gas-saturated reservoir is responsible for polarity reversal.
文摘Background P-wave dispersion （PWD）, a measure of heterogeneity of atrial refractoriness, is defined as the difference between the maximum and minimum P-wave duration. In patients with severe aortic stenosis （AS）, P-wave duration and PWD were shown to be increased, indicating atrial electrical remodeling. However, the effect of transcatheter aortic valve replacement （TAVR） on P-wave morphology has not been established yet. The aim of this study is to assess the short and long-term effects of TAVR with two types of bioprosthetic valves on P-wave duration and PWD in association with left atrial （LA） size. Methods Fifty-two （36 female） eligible patients in sinus rhythm who underwent transfemoral TAVR between June 01, 2012 and July 31, 2014 with either a Medtronic CoreValve （MCV） （n = 32） or an Edwards SAPIEN XT Valve （n = 20） were enrolled. Standard 12-lead electrocardiogram and echocardiographic evaluations were per- formed pre-procedurally, post-TAVR day one and 6 months post-TAVR. P-wave duration and PWD were measured and correlation analyses with echocardiographic variables were performed. Results P-wave duration and PWD were significantly decreased on post-TAVR day one （P 〈 0.05）. They continued to decrease during the six month follow-up period, but were not significantly different from short-term values （P 〉 0.05）. The decrease of LA diameter was found significant at the sixth-months of follow-up （P 〈 0.05）. These changes were independent from the types of bioprosthetic valves implanted （P 〉 0.05）. A positive correlation was detected between minimum P-wave duration and maximum aortic valve gradients at post-TAVR day one （r = 0.297, P = 0.032）. Conclusions P-wave duration and PWD were significantly reduced early after TAVR indicating early reverse atrial electrical remodeling. Moreover, structural reverse remodeling of atrium was detected at the 6-months of follow-up. The effects of two types of bioprosthetic valves on atrial remodeling were similar.
基金This research is sponsored by China National Natural Science Foundation （40574050, 40521002） and CNPC Key Research Program （06A 10101）.
文摘In recent years, long-offset exploration has been widely used, especially on marine seismic surveys. Conventional AVO analysis is insufficient for long-offset seismic data. To widen the application range of AVO analysis, we present a new P-wave reflection coefficient approximation applicable to long-offset data. Our result is similar to the well known Shuey formula which can be treated as an approximation to our results for short-offset seismic data.
基金Supported by National Natural Science Foundation of China (No. 50978156 and No. 50908183)
文摘The indirect boundary element method (IBEM) is used to study the surface motion of an alluvial valley in layered half-space for incident plane P-waves based on Wolf’s theory. Firstly, the free field response can be solved by the direct stiffness method, and the scattering wave response is calculated by Green’s functions of distributed loads acting on inclined lines in a layered half-space. The method is verified by comparing its results with literature and numerical analyses are performed by taking the amplification of incident plane P-waves by an alluvial valley in one soil layer resting on bedrock as an example. The results show that there exist distinct differences between the wave amplification by an alluvial valley embedded in layered half-space and that in homogeneous half-space and there is interaction between the valley and the soil layer. The amplitudes are relatively large when incident frequencies are close to the soil layer’s resonant frequencies.
基金supported by the National Natural Science Foundation of China (Nos. 41273066 and MRE200805)
文摘To revise P-wave velocity and thickness of the hydrate layer in the Shenhu area of the South China Sea, acoustic and resistivity logging curves are reanalyzed. The waterlogging phenomenon is found in the shallow sediments of five drilling wells, which causes P-wave velocity to approximate the propagation velocity of sea water(about 1500 m s-1). This also affects the identification of the hydrate layer and results in the underestimate of its thickness. In addition, because there could be about a 5 m thick velocity ramp above or below the hydrate layer as interpreted by acoustic and resistivity logging curves, the recalibrated thickness of this layer is less than the original estimated thickness. The recalibrated P-wave velocity of the hydrate layer is also higher than the original estimated velocity. For the drilling well with a relatively thin hydrate layer, the velocity ramp plays a more important role in identifying and determining the thickness of the layer.
基金supported in part by the Top-Notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)the Startup Fund of Nanjing University of Aeronautics and Astronautics(No.1008-0280YAT21004)
文摘Combining two Bose-Einstein condensates(BECs)may result in a miscible or immiscible mixture.In this study,we investigate the miscibility-immiscibility transition of binary BEC mixture trapped in an isotropic harmonic potential,with both inter-species s-wave and p-wave scattering interaction included.The mean-field Gross-Pitaevskii equations with p-wave interaction term are numerically solved to obtain the ground-state phase diagram.Due to the pwave interaction competing with isotropic s-wave interaction,the spatial density profile of binary BEC mixtures transforming from immiscible phase to miscible phase is observed.The p-wave interaction caused miscibility can be observed in current experiments of Bose-Bose mixture tuned near a p-wave Feshbach resonance.
基金The project supported by the Natural Science Foundation of the Education Commission 0f Jiangsu Province of China under Grant No. 06KJB140009
文摘The Josephson currents in s-wave superconductor/ferromagnet insulator/p-wave superconductor（s/FI/p） junctions are calculated as a function of temperature and the phase taking into account the roughness scattering effect at interface. The phase dependence of the Josephson current I （φ） between s-wave and px-wave superconductor is predicted to be sin（2φ）. The ferromagnet scattering effect, the barrier strength, and the roughness strength at interface suppress the dc currents in s/FI/p junction.
