In the process of accurate interpretation of multi-wave seismic data,we wanted to solve the problem of multi-wave information recognition.Based on techniques of elastic wave forwarding,targeting the geological model o...In the process of accurate interpretation of multi-wave seismic data,we wanted to solve the problem of multi-wave information recognition.Based on techniques of elastic wave forwarding,targeting the geological model of a reservoir of an oil field exploration area,we used a high-order staggered-grid difference technology to simulate many shots of seismic records of nonzero offset shots,implemented multi-wave seismic data processing to acquire the CMP of P waves and converted waves,NMO traces of CCP pre stacks,including AVA information and superposition profiles.Based on the AVA calculation of the model,the layer parameters of the model and the forwarding wave field relations of the P-S wave,we also compared and studied the correspondence between P waves and converted waves.The results of our analysis show that the results from simulation and from the AVO analysis are consistent.Significant wave field differences between P waves and converted waves in the same reservoir were found,which are helpful in recognizing and interpreting the multi-wave information in this area.We made use of the multi-wave data to provide the important guidelines for reservoir prediction.展开更多
In seismic exploration for coal, seismic waves are very difficult to transmit downward because of high velocity protective layers, making the reflection information very hard to receive above ground. Based on the Snel...In seismic exploration for coal, seismic waves are very difficult to transmit downward because of high velocity protective layers, making the reflection information very hard to receive above ground. Based on the Snell law and the Zoeppritz equation, we studied the relationship between the incidence angle and reflection seismic wave energy using a forward model of level media. The result shows that the seismic wave energy has a sudden increase at the critical angle. Based on the energy propagation rule, using big offset to receive the seismic wave energy under a protective layer can effectively reduce its protection effect.展开更多
Based on the pseudo-analytical equation of electromagnetic log for layered formation,an optimal boundary match method is proposed to adaptively truncate the encountered formation structures.An efficient integral metho...Based on the pseudo-analytical equation of electromagnetic log for layered formation,an optimal boundary match method is proposed to adaptively truncate the encountered formation structures.An efficient integral method is put forward to significantly accelerate the convergence of Sommerfeld integral.By asymptotically approximating and subtracting the first reflection/transmission waves from the scattered field,the new Sommerfeld integral method has addressed difficulties encountered by the traditional digital filtering method,such as low computational precision and limited operating range,and realized the acceleration of the computation speed of logging-while-drilling electromagnetic measurements(LWD EM).By making use of the priori information from the offset/pilot wells and interactively adjusting the formation model,the optimum initial guesses of the inversion model is determined in order to predict the nearby formation boundaries.The gradient optimization algorithm is developed and an interactive inversion system for the LWD EM data from the horizontal wells is established.The inverted results of field data demonstrated that the real-time interactive inversion method is capable of providing the accurate boundaries of layers around the wellbore from the LWD EM,and it will benefit the wellbore trajectory optimization and reservoir interpretation.展开更多
This study used the stable and convergent Dufort-Frankel method to differentially discretize the diffusion equation of the ground-well transient electromagnetic secondary field.The absorption boundary condition of com...This study used the stable and convergent Dufort-Frankel method to differentially discretize the diffusion equation of the ground-well transient electromagnetic secondary field.The absorption boundary condition of complex frequency-shifted perfectly matched layer(CFS-PML)was used for truncation so that the low-frequency electromagnetic wave can be better absorbed at the model boundary.A typical three-dimensional(3D)homogeneous half-space model was established and a low-resistivity cube model was analyzed under the half-space condition.The response patterns and drivers of the low-resistivity cube model were discussed under the influence of a low-resistivity overburden.The absorption boundary conditions of CFS-PML significantly affected the low-frequency electromagnetic waves.For a low-resistivity cube around the borehole,its response curve exhibited a single-peak,and the extreme point of the curve corresponded to the center of the low-resistivity body.When the low-resistivity cube was directly below the borehole,the response curve showed three extreme values(two high and one low),with the low corresponding to the center of the low-resistivity body.The total field response of the low-resistivity overburden was stronger than that of the uniform half-space model due to the low-resistivity shielding effect of electromagnetic waves.When the receiving-transmitting distance gradually increased,the effect of the low-resistivity overburden was gradually weakened,and the response of the low-resistivity cube was strengthened.It was affected by the ratio of the overburden resistivity to the resistivity of the low-resistivity body.展开更多
Research on the underwater target scattering can provide important theoretical support for target detection. The scattering model of cylindrical shell is established in this paper. It is found that the forward target ...Research on the underwater target scattering can provide important theoretical support for target detection. The scattering model of cylindrical shell is established in this paper. It is found that the forward target strength is much stronger and varies with angles of incident wave less significantly than backward target strength. The received forward signal strength fluctuates with the target moving due to the interference between direct signal and scattering signal, which is most significant when the target approaches the baseline. An experiment is carried out in an anechoic tank to validate the scattering model. The method of acquisiting forward scattering in the tank is proposed. The forward and the backward target strengths are achieved by using the pulse compression technology, and they axe about 3dB less than the modeling results. The forward scattering phenomena of quiescent and moving targets are measured, which are similar to modeling results with different target types.展开更多
Based on the control theories of PID, fuzzy logic and expert PID, the driver models are built and applied in the forward simulation for hybrid electric vehicles （HEV）. The impact to the vehicle speed tracking and th...Based on the control theories of PID, fuzzy logic and expert PID, the driver models are built and applied in the forward simulation for hybrid electric vehicles （HEV）. The impact to the vehicle speed tracking and the fuel economy is compared among the different driver models. The different human-simulated characteristics of the driver models are emphatically analyzed. The analysis results indicate that the driver models based on PID, simple fuzzy logic and expert PID are corresponding to the handling characteristics of different drives. The driver models of different human-simulated characteristics bring the handling divergence of drivers with different driving level and habit to the HEV forward simulation, and that is significant to the all-around verification and validation of the control strategy for HEV. System simulation results of different driver models validate the impact of driver models to the dynamic and fuel economy performance of HEV.展开更多
基于典型地面背景电磁散射特性的研究,提出了介质粗糙地面上目标散射中心正向建模的方法。首先,通过蒙特卡罗方法随机生成粗糙面,利用高斯谱模拟三维粗糙地面模型,采用介电常数对不同地面材料进行表征;然后,采用正向途径并结合射线追踪...基于典型地面背景电磁散射特性的研究,提出了介质粗糙地面上目标散射中心正向建模的方法。首先,通过蒙特卡罗方法随机生成粗糙面,利用高斯谱模拟三维粗糙地面模型,采用介电常数对不同地面材料进行表征;然后,采用正向途径并结合射线追踪、分集技术将复杂的地面环境与MSTAR(Moving and Stationary Target Acquisition and Recognition)库中的BMP2步兵战车目标模型的整体散射离散为多个散射源的集合,再结合粗糙地面的不同介电常数进行分析,利用高频近似方法进行求解;最后,通过重构的合成孔径雷达(synthetic aperture radar,SAR)图像与MSTAR库实测数据集对比进行验证。结果表明,本文提出的介质粗糙地面上目标散射中心正向建模方法能够提高与实测图像数据的相似度,验证了其有效性。展开更多
In the paper, we concentrate on the infl uence of heterogeneity on the performance of forwarding algorithms under opportunistic networks. Therefore, we first describe two different heterogeneous network models, and ca...In the paper, we concentrate on the infl uence of heterogeneity on the performance of forwarding algorithms under opportunistic networks. Therefore, we first describe two different heterogeneous network models, and capture the heterogeneity which concern mobile nodes' contact dynamics under the individual models and the spatial models. Then we investigate inter-contact time is not fully follow exponential distribution and compare the performance of the delivery delay between direct forwarding protocol and three-hop forwarding protocol under three network models. We illustrate the performance of message delivery delay under the spray and wait protocol and prophet protocol from simulation results. Our simulation results show that the heterogeneity should be considered for the performance of forwarding protocols.展开更多
基金the Doctor Research Fund for Universities of China (No.20070616004)the National High Technology Research and Development Program of China (No.2007AA060505)
文摘In the process of accurate interpretation of multi-wave seismic data,we wanted to solve the problem of multi-wave information recognition.Based on techniques of elastic wave forwarding,targeting the geological model of a reservoir of an oil field exploration area,we used a high-order staggered-grid difference technology to simulate many shots of seismic records of nonzero offset shots,implemented multi-wave seismic data processing to acquire the CMP of P waves and converted waves,NMO traces of CCP pre stacks,including AVA information and superposition profiles.Based on the AVA calculation of the model,the layer parameters of the model and the forwarding wave field relations of the P-S wave,we also compared and studied the correspondence between P waves and converted waves.The results of our analysis show that the results from simulation and from the AVO analysis are consistent.Significant wave field differences between P waves and converted waves in the same reservoir were found,which are helpful in recognizing and interpreting the multi-wave information in this area.We made use of the multi-wave data to provide the important guidelines for reservoir prediction.
基金Projects 40574058 supported by the National Natural Science Foundation of China2005cb221500 by the National Basic Research Program of China 03(2007) by the Scientific and Technological Project about Geology and Mineral Resources of Henan Land Resources Department
文摘In seismic exploration for coal, seismic waves are very difficult to transmit downward because of high velocity protective layers, making the reflection information very hard to receive above ground. Based on the Snell law and the Zoeppritz equation, we studied the relationship between the incidence angle and reflection seismic wave energy using a forward model of level media. The result shows that the seismic wave energy has a sudden increase at the critical angle. Based on the energy propagation rule, using big offset to receive the seismic wave energy under a protective layer can effectively reduce its protection effect.
基金Supported by the National Natural Science Foundation of China(41904109,41974146)National Science and Technology Major Project(2017ZX05019-005)+2 种基金China Postdoctoral Science Foundation(2018M640663)the Shandong Province Postdoctoral Innovation Projects(sdbh20180025)National Key Laboratory of Electromagnetic Environment Projects(6142403200307)。
文摘Based on the pseudo-analytical equation of electromagnetic log for layered formation,an optimal boundary match method is proposed to adaptively truncate the encountered formation structures.An efficient integral method is put forward to significantly accelerate the convergence of Sommerfeld integral.By asymptotically approximating and subtracting the first reflection/transmission waves from the scattered field,the new Sommerfeld integral method has addressed difficulties encountered by the traditional digital filtering method,such as low computational precision and limited operating range,and realized the acceleration of the computation speed of logging-while-drilling electromagnetic measurements(LWD EM).By making use of the priori information from the offset/pilot wells and interactively adjusting the formation model,the optimum initial guesses of the inversion model is determined in order to predict the nearby formation boundaries.The gradient optimization algorithm is developed and an interactive inversion system for the LWD EM data from the horizontal wells is established.The inverted results of field data demonstrated that the real-time interactive inversion method is capable of providing the accurate boundaries of layers around the wellbore from the LWD EM,and it will benefit the wellbore trajectory optimization and reservoir interpretation.
基金This work was supported by China Postdoctoral Science Foundation(No.2022M723391)the Science and Technology Innovation Project of Higher Education in Shanxi Province(No.2019L0754)+1 种基金the Central Guiding Local Science and Technology Development Fund Project(No.YDZJSX2021B021)Shanxi Province Basic Research Plan General Project(No.202203021221294).
文摘This study used the stable and convergent Dufort-Frankel method to differentially discretize the diffusion equation of the ground-well transient electromagnetic secondary field.The absorption boundary condition of complex frequency-shifted perfectly matched layer(CFS-PML)was used for truncation so that the low-frequency electromagnetic wave can be better absorbed at the model boundary.A typical three-dimensional(3D)homogeneous half-space model was established and a low-resistivity cube model was analyzed under the half-space condition.The response patterns and drivers of the low-resistivity cube model were discussed under the influence of a low-resistivity overburden.The absorption boundary conditions of CFS-PML significantly affected the low-frequency electromagnetic waves.For a low-resistivity cube around the borehole,its response curve exhibited a single-peak,and the extreme point of the curve corresponded to the center of the low-resistivity body.When the low-resistivity cube was directly below the borehole,the response curve showed three extreme values(two high and one low),with the low corresponding to the center of the low-resistivity body.The total field response of the low-resistivity overburden was stronger than that of the uniform half-space model due to the low-resistivity shielding effect of electromagnetic waves.When the receiving-transmitting distance gradually increased,the effect of the low-resistivity overburden was gradually weakened,and the response of the low-resistivity cube was strengthened.It was affected by the ratio of the overburden resistivity to the resistivity of the low-resistivity body.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10774119)the program for New Century Excellent Talents in University,China (Grant No. NCET-08-0455)+2 种基金the Natural Science Foundation of Shaanxi province,China(Grant No. SJ08F07)the Foundation of National Laboratory of Acousticsthe Northwestern Polytechnical University NPU Foundation for Fundamental Research,China (Grant No. 2007004)
文摘Research on the underwater target scattering can provide important theoretical support for target detection. The scattering model of cylindrical shell is established in this paper. It is found that the forward target strength is much stronger and varies with angles of incident wave less significantly than backward target strength. The received forward signal strength fluctuates with the target moving due to the interference between direct signal and scattering signal, which is most significant when the target approaches the baseline. An experiment is carried out in an anechoic tank to validate the scattering model. The method of acquisiting forward scattering in the tank is proposed. The forward and the backward target strengths are achieved by using the pulse compression technology, and they axe about 3dB less than the modeling results. The forward scattering phenomena of quiescent and moving targets are measured, which are similar to modeling results with different target types.
基金Supported by the National Natural Science Foundation of China(50905018)
文摘Based on the control theories of PID, fuzzy logic and expert PID, the driver models are built and applied in the forward simulation for hybrid electric vehicles （HEV）. The impact to the vehicle speed tracking and the fuel economy is compared among the different driver models. The different human-simulated characteristics of the driver models are emphatically analyzed. The analysis results indicate that the driver models based on PID, simple fuzzy logic and expert PID are corresponding to the handling characteristics of different drives. The driver models of different human-simulated characteristics bring the handling divergence of drivers with different driving level and habit to the HEV forward simulation, and that is significant to the all-around verification and validation of the control strategy for HEV. System simulation results of different driver models validate the impact of driver models to the dynamic and fuel economy performance of HEV.
文摘基于典型地面背景电磁散射特性的研究,提出了介质粗糙地面上目标散射中心正向建模的方法。首先,通过蒙特卡罗方法随机生成粗糙面,利用高斯谱模拟三维粗糙地面模型,采用介电常数对不同地面材料进行表征;然后,采用正向途径并结合射线追踪、分集技术将复杂的地面环境与MSTAR(Moving and Stationary Target Acquisition and Recognition)库中的BMP2步兵战车目标模型的整体散射离散为多个散射源的集合,再结合粗糙地面的不同介电常数进行分析,利用高频近似方法进行求解;最后,通过重构的合成孔径雷达(synthetic aperture radar,SAR)图像与MSTAR库实测数据集对比进行验证。结果表明,本文提出的介质粗糙地面上目标散射中心正向建模方法能够提高与实测图像数据的相似度,验证了其有效性。
基金supported by the National Natural Science Foundation of China under Grant No.61171097
文摘In the paper, we concentrate on the infl uence of heterogeneity on the performance of forwarding algorithms under opportunistic networks. Therefore, we first describe two different heterogeneous network models, and capture the heterogeneity which concern mobile nodes' contact dynamics under the individual models and the spatial models. Then we investigate inter-contact time is not fully follow exponential distribution and compare the performance of the delivery delay between direct forwarding protocol and three-hop forwarding protocol under three network models. We illustrate the performance of message delivery delay under the spray and wait protocol and prophet protocol from simulation results. Our simulation results show that the heterogeneity should be considered for the performance of forwarding protocols.
