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Second-generation wavelet finite element based on the lifting scheme for GPR simulation

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Applied Geophysics 2020年第1期17卷 143-153,170页

作者： feng de-shan Zhang Hua Wang Xun School of Geosciences and Info-Physics Central South UniversityChangsha 410083China Key Laboratory of Metallogenic Prediction of Nonferrous Metals Ministry of EducationChangsha 410083China

Ground-penetrating radar(GPR)is a highly efficient,fast and non-destructive exploration method for shallow ***-precision numerical simulation method is employed to improve the interpretation precision of ***-generation wavelet finite element is introduced into the forward modeling of the *** the finite element basis function,the second-generation wavelet scaling function constructed by the scheme is characterized as having multiple scales and *** function can change the analytical scale arbitrarily according to actual *** can adopt a small analysis scale at a large gradient to improve the precision of analysis while adopting a large analytical scale at a small gradient to improve the efficiency of *** approach is beneficial to capture the local mutation characteristics of the solution and improve the resolution without changing mesh subdivision to realize the efficient solution of the forward GPR *** algorithm is applied to the numerical simulation of line current radiation source and tunnel non-dense lining model with analytical *** show that the solution results of the secondgeneration wavelet finite element are in agreement with the analytical solutions and the conventional finite element solutions,thereby verifying the accuracy of the second-generation wavelet finite element ***,the second-generation wavelet finite element algorithm can change the analysis scale arbitrarily according to the actual problem without subdividing grids *** adaptive algorithm is superior to traditional scheme in grid refinement and basis function order increase,which makes this algorithm suitable for solving complex GPR forward-modeling problems with large gradient and singularity.

关键词： Ground penetrating radar wave equation second-generation wavelet finite element method lifting scheme forward modeling

An element-free Galerkin method for ground penetrating radar numerical simulation

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Journal of Central South University 2015年第1期22卷 261-269页

作者：冯德山郭荣文王洪华 School of Geosciences and Info-Physics Central South University Key Laboratory of Metallogenic Prediction of Nonferrous Metals Ministry of Education(Central South University)

An element-free Galerkin method(EFGM) is used to solve the two-dimensional(2D) ground penetrating radar(GPR)modelling problems, due to its simple pre-processing, the absence of elements and high accuracy. Different from element-based numerical methods, this approach makes nodes free from the elemental restraint and avoids the explicit mesh discretization. First, we derived the boundary value problem for the 2D GPR simulation problems. Second, a penalty function approach and a boundary condition truncated method were used to enforce the essential and the absorbing boundary conditions, respectively. A three-layered GPR model was used to verify our element-free approach. The numerical solutions show that our solutions have an excellent agreement with solutions of a finite element method(FEM). Then, we used the EFGM to simulate one more complex model to show its capability and limitations. Simulation results show that one obvious advantage of EFGM is the absence of element mesh, which makes the method very flexible. Due to the use of MLS fitting, a key feature of EFM, is that both the dependent variable and its gradient are continuous and have high precision.

关键词： element-free Galerkin method moving least-squares method ground penetrating radar forward simulation

基于单轴各向异性完全匹配层边界条件的ADI-FDTD三维GPR全波场正演

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中南大学学报（自然科学版） 2011年第8期42卷 2363-2371页

作者：冯德山谢源中南大学地球科学与信息物理学院湖南长沙410083

基于交替方向隐式差分(ADI-FDTD)法突破了CFL稳定性条件的约束,具有无条件稳定性的特点,而单轴各向异性完全匹配层(UPML)边界条件具有宽频带吸收特性、不需要对电场和磁场进行分裂、迭代公式简单、便于编程的特点,提出基于UPML边界条件... 详细信息

基于交替方向隐式差分(ADI-FDTD)法突破了CFL稳定性条件的约束,具有无条件稳定性的特点,而单轴各向异性完全匹配层(UPML)边界条件具有宽频带吸收特性、不需要对电场和磁场进行分裂、迭代公式简单、便于编程的特点,提出基于UPML边界条件的ADI-FDTD三维探地雷达数值模拟算法;通过对三维Maxwell方程进行离散化,推导GPR波的ADI-FDTD及其UPML边界条件2个子时间步的迭代差分公式,以及计算步骤。开发ADI-FDTD三维模拟程序,并对三维复杂GPR模型进行正演模拟,分析该模型的剖面图、切片图及不同时刻6个分量的全波场快照。研究结果表明:由全波场快照可以了解雷达波形在空间中的传播过程及变化规律,有助于对雷达资料进行更可靠、更准确的解释;基于UPML边界条件的ADI-FDTD算法消除了截断边界处的强反射,能对三维复杂的GPR模型进行快速、高效模拟。

关键词：探地雷达交替方向隐式有限差分法单轴各向异性完全匹配层正演

An artificial intelligence diabetes management architecture based on 5G

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Digital Communications and Networks 2024年第1期10卷 75-82页

作者： Ruochen Huang Wei feng shan Lu Tao shan Changwei Zhang Yun Liu department of Geriatrics The First Affiliated Hospital of Nanjing Medical UniversityNanjing210096China department of Information The First Afliated Hospital of Nanjing Medical UniversityNanjing210096China department of Medical Informatics School of Biomedical Engineering and InformaticsNanjing Medical UniversityNanjing211166China department of Outpatient The First Affiliated Hospital of Nanjing Medical UniversityNanjing210096China Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing210003China

Along with the development of 5G network and Internet of Things technologies,there has been an explosion in personalized healthcare *** the 5G and Artificial Intelligence(Al)is introduced into diabetes management architecture,it can increase the efficiency of existing systems and complications of diabetes can be handled more effectively by taking advantage of *** this article,we propose a 5G-based Artificial Intelligence Diabetes Management architecture(AIDM),which can help physicians and patients to manage both acute complications and chronic *** AIDM contains five layers:the sensing layer,the transmission layer,the storage layer,the computing layer,and the application *** build a test bed for the transmission and application ***,we apply a delay-aware RA optimization based on a double-queue model to improve access efficiency in smart hospital wards in the transmission *** application layer,we build a prediction model using a deep forest *** on real-world data show that our AIDM can enhance the efficiency of diabetes management and improve the screening rate of diabetes as well.

关键词： Diabetes 5G Artificial intelligence deep forest Smart hospital ward

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探地雷达小波域三维波动方程偏移

地球物理学报 2008年第2期51卷 566-574页

作者：冯德山戴前伟中南大学信息物理工程学院

阐述了矩阵多分辨分析理论中的标准形式与非标准形式,并以Hilbert算子为例,说明了算子多分辨表示的压缩效果,为小波域偏移算法奠定了理论基础.从三维雷达波动方程出发,利用爆炸反射原理和浮动坐标变换,推导出三维探地雷达波动方程差分格... 详细信息

阐述了矩阵多分辨分析理论中的标准形式与非标准形式,并以Hilbert算子为例,说明了算子多分辨表示的压缩效果,为小波域偏移算法奠定了理论基础.从三维雷达波动方程出发,利用爆炸反射原理和浮动坐标变换,推导出三维探地雷达波动方程差分格式,并通过方程分裂算法及小波多分辨算法,在小波域求解波场外推矩阵,进而得到探地雷达小波域三维波动方程偏移算法,在此基础上,开发了探地雷达小波域偏移处理程序,并把该程序应用于三个球体空洞的3-D正演结果及实际的雷达数据中,通过对比偏移处理前后的雷达资料,得知该三维偏移算法能使3-D正演剖面中的反射波归位、绕射波收敛,极大地提高了雷达剖面的分辨率,有利于探地雷达资料的地质解释.

关键词：探地雷达小波域波动方程偏移

基于小波多分辨探地雷达三维正演模拟及偏移处理

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中南大学学报（自然科学版） 2007年第4期38卷 758-763页

作者：冯德山戴前伟中南大学信息物理工程学院

通过对Maxwell方程进行离散化,导出DB2-MRTD算法的探地雷达3D差分公式,并开发探地雷达MRTD法正演程序,利用该程序对三维雷达模型进行正演模拟,得到其相应的正演合成三维剖视图及切片图;通过对这些模拟结果进行分析,验证MRTD法在探地雷... 详细信息

通过对Maxwell方程进行离散化,导出DB2-MRTD算法的探地雷达3D差分公式,并开发探地雷达MRTD法正演程序,利用该程序对三维雷达模型进行正演模拟,得到其相应的正演合成三维剖视图及切片图;通过对这些模拟结果进行分析,验证MRTD法在探地雷达三维正演中的有效性;利用爆炸反射原理和浮动坐标变换,推导出三维探地雷达波动方程差分格式,并把波场外推矩阵在小波域进行求解,进而得到探地雷达小波域三维偏移算法及偏移处理程序,把该程序应用于正演结果中。对比偏移处理前、后的雷达资料发现,该三维偏移算法能使3D正演剖面中的反射波归位、绕射波收敛,极大地提高了雷达剖面的分辨率。

关键词：探地雷达时域多分辨法正演偏移处理

3D prestack reverse time migration of ground penetrating radar data based on the normalized correlation imaging condition

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Applied Geophysics 2020年第5期17卷 709-718,901页

作者： Wang Hong-Hua Gong Jun-bo Zhang Zhi Xiong Bin Lv Yu-zeng feng de-shan Dai Qian-wei College of Earth Sciences Guilin University of TechnologyGuilin 541004China Guangxi Key Laboratory of Hidden Metallic Ore deposits Exploration Guilin 541004China School of Geosciences and Info-Physics Central South UniversityChangsha 410083China.

The reverse time migration(RTM)of ground penetrating radar(GPR)is usually implemented in its two-dimensional(2D)form,due to huge computational ***,2D RTM algorithm is difficult to focus the scattering signal and produce a high precision subsurface image when the object is buried in a complicated subsurface *** better handle the multi-off set GPR data,we propose a three-dimensional(3D)prestack RTM *** high-order fi nite diff erence time domian(FDTD)method,with the accuracy of eighth-order in space and second-order in time,is applied to simulate the forward and backward extrapolation electromagnetic fi *** addition,we use the normalized correlation imaging condition to obtain pre-stack RTM result and the Laplace fi lter to suppress the low frequency noise generated during the correlation *** numerical test of 3D simulated GPR data demonstrated that 3D RTM image shows excellent coincidence with the true *** with 2D RTM image,the 3D RTM image can more clearly and accurately refl ect the 3D spatial distribution of the target,and the resolution of the imaging results is far ***,the application of observed GPR data further validates the eff ectiveness of the proposed 3D GPR RTM algorithm,and its fi nal image can more reliably guide the subsequent interpretation.

关键词： Ground Penetrating Radar(GPR) 3D Reverse Time Migration(RTM) Finite Diff erence Time Domain(FDTD) Normalized correlation imaging condition

探地雷达的正演模拟及有限差分波动方程偏移处理

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中南大学学报（自然科学版） 2006年第2期37卷 361-365页

作者：冯德山戴前伟何继善中南大学信息物理工程学院湖南长沙410083

利用麦克斯韦方程和有限差分法,推导出雷达波的二维有限差分正演方程组,并运用该正演方程对“V”字形地电模型和同一斜面上的5个圆的地电模型进行正演合成,得到其相应的正演合成剖面;把该正演合成的剖面与实际模型相比,得出正演合成图... 详细信息

利用麦克斯韦方程和有限差分法,推导出雷达波的二维有限差分正演方程组,并运用该正演方程对“V”字形地电模型和同一斜面上的5个圆的地电模型进行正演合成,得到其相应的正演合成剖面;把该正演合成的剖面与实际模型相比,得出正演合成图与实际模型的示意图在形状上有一定的差别,这是剖面中异常点处的绕射波所致;为了提高雷达资料的解释精度,对正演合成的雷达剖面进行后处理,运用雷达上行波反向外推有限差分偏移法,对2个正演合成的雷达剖面进行偏移处理,通过对比偏移处理前后的雷达正演剖面,采用有限差分偏移法能使雷达正演剖面中的反射波归位,绕射波收敛,从而大大提高了雷达正演剖面的分辨率,有利于探地雷达剖面的地质解释和验证偏移方法的有效性。

关键词：探地雷达正演模拟有限差分法波动方程偏移

Review of Iron-Based Catalysts for Carbon Dioxide Fischer-Tropsch Synthesis

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Transactions of Tianjin University 2024年第2期30卷 178-197页

作者： Ji-Yue Jia Yu-Ling shan Yong-Xiao Tuo Hao Yan Xiang feng de Chen State Key Laboratory of Heavy Oil Processing China University of PetroleumQingdao 266580China College of Chemical Engineering Qingdao University of Science and TechnologyQingdao 266042China department of Chemical Engineering Norwegian University of Science and Technology7491 TrondheimNorway

Capturing and utilizing CO_(2)from the production process is the key to solving the excessive CO_(2)emission problem. CO_(2)hydrogenation with green hydrogen to produce olefins is an effective and promising way to utilize CO_(2)and produce valuable chemicals. The olefins can be produced by CO_(2)hydrogenation through two routes, i.e., CO_(2)-FTS (carbon dioxide Fischer- Tropsch synthesis) and MeOH (methanol-mediated), among which CO_(2)-FTS has significant advantages over MeOH in practical applications due to its relatively high CO_(2)conversion and low energy consumption potentials. However, the CO_(2)-FTS faces challenges of difficult CO_(2)activation and low olefins selectivity. Iron-based catalysts are promising for CO_(2)-FTS due to their dual functionality of catalyzing RWGS and CO-FTS reactions. This review summarizes the recent progress on iron-based catalysts for CO_(2)hydrogenation via the FTS route and analyzes the catalyst optimization from the perspectives of additives, active sites, and reaction mechanisms. Furthermore, we also outline principles and challenges for rational design of high-performance CO_(2)-FTS catalysts.

关键词： CO_(2)hydrogenation Olefins CO_(2)-FTS Iron-based catalysts