In oil and mineral exploration, gravity gradient tensor data include higher- frequency signals than gravity data, which can be used to delineate small-scale anomalies. However, full-tensor gradiometry （FTG） data are...In oil and mineral exploration, gravity gradient tensor data include higher- frequency signals than gravity data, which can be used to delineate small-scale anomalies. However, full-tensor gradiometry （FTG） data are contaminated by high-frequency random noise. The separation of noise from high-frequency signals is one of the most challenging tasks in processing of gravity gradient tensor data. We first derive the Cartesian equations of gravity gradient tensors under the constraint of the Laplace equation and the expression for the gravitational potential, and then we use the Cartesian equations to fit the measured gradient tensor data by using optimal linear inversion and remove the noise from the measured data. Based on model tests, we confirm that not only this method removes the high- frequency random noise but also enhances the weak anomaly signals masked by the noise. Compared with traditional low-pass filtering methods, this method avoids removing noise by sacrificing resolution. Finally, we apply our method to real gravity gradient tensor data acquired by Bell Geospace for the Vinton Dome at the Texas-Louisiana border.展开更多
针对PM2.5遥感模型对气溶胶细粒子比FMF(Fine mode fraction)参数的需求,结合多光谱偏振传感器对大气探测的优势,基于最优估计OE(Optimal Estimation)反演框架,提出了一种基于线偏振度(Degree of Linear Polarization)测量的FMF最优化...针对PM2.5遥感模型对气溶胶细粒子比FMF(Fine mode fraction)参数的需求,结合多光谱偏振传感器对大气探测的优势,基于最优估计OE(Optimal Estimation)反演框架,提出了一种基于线偏振度(Degree of Linear Polarization)测量的FMF最优化反演方法。采用矢量化的辐射传输模式UNL-VRTM进行地基天空光的线偏振度观测模拟,分析了线偏振度对FMF参数的波段敏感性,并基于仿真数据开展了算法的反演测试。研究结果表明:偏振测量在长波近红外波段对FMF的敏感性高于可见光波段;基于OE框架的FMF反演算法具有良好的闭合性;在地基天顶观测模式下,引入线偏振度测量参与反演能够有效提高FMF的反演精度,FMF反演误差从1.4%下降到了0.18%。最优化反演方法对于气溶胶遥感具有一定的潜力和可行性,有望成为提高PM2.5遥感监测能力的新途径。展开更多
Wireless sensor networks are extremely vulnerable to various security threats.The intrusion detection method based on game theory can effectively balance the detection rate and energy consumption of the system.The acc...Wireless sensor networks are extremely vulnerable to various security threats.The intrusion detection method based on game theory can effectively balance the detection rate and energy consumption of the system.The accurate analysis of the attack behavior of malicious sensor nodes can help to configure intrusion detection system,reduce unnecessary system consumption and improve detection efficiency.However,the completely rational assumption of the traditional game model will cause the established model to be inconsistent with the actual attack and defense scenario.In order to formulate a reasonable and effective intrusion detection strategy,we introduce evolutionary game theory to establish an attack evolution game model based on optimal response dynamics,and then analyze the attack behavior of malicious sensor nodes.Theoretical analysis and simulation results show that the evolution trend of attacks is closely related to the number of malicious sensors in the network and the initial state of the strategy,and the attacker can set the initial strategy so that all malicious sensor nodes will eventually launch attacks.Our work is of great significance to guide the development of defense strategies for intrusion detection systems.展开更多
The problem for determining the exchange rate function of 2D CCPF model by measurements on the partial boundary is considered and solved as one PDE-constraint optimization problem. The optimal variant is the minimum o...The problem for determining the exchange rate function of 2D CCPF model by measurements on the partial boundary is considered and solved as one PDE-constraint optimization problem. The optimal variant is the minimum of a cost functional that quantifies the difference between the measurements and the exact solutions. Gradientbased algorithm is used to solve this optimization problem. At each step, the derivative of the cost functional with respect to the exchange rate function is calculated and only one forward solution and one adjoint solution are needed. One method based on the adjoint equation is developed and implemented. Numerical examples show the efficiency of the adjoint method.展开更多
基金financially supported by the SinoProbe-09-01(201011078)
文摘In oil and mineral exploration, gravity gradient tensor data include higher- frequency signals than gravity data, which can be used to delineate small-scale anomalies. However, full-tensor gradiometry （FTG） data are contaminated by high-frequency random noise. The separation of noise from high-frequency signals is one of the most challenging tasks in processing of gravity gradient tensor data. We first derive the Cartesian equations of gravity gradient tensors under the constraint of the Laplace equation and the expression for the gravitational potential, and then we use the Cartesian equations to fit the measured gradient tensor data by using optimal linear inversion and remove the noise from the measured data. Based on model tests, we confirm that not only this method removes the high- frequency random noise but also enhances the weak anomaly signals masked by the noise. Compared with traditional low-pass filtering methods, this method avoids removing noise by sacrificing resolution. Finally, we apply our method to real gravity gradient tensor data acquired by Bell Geospace for the Vinton Dome at the Texas-Louisiana border.
文摘针对PM2.5遥感模型对气溶胶细粒子比FMF(Fine mode fraction)参数的需求,结合多光谱偏振传感器对大气探测的优势,基于最优估计OE(Optimal Estimation)反演框架,提出了一种基于线偏振度(Degree of Linear Polarization)测量的FMF最优化反演方法。采用矢量化的辐射传输模式UNL-VRTM进行地基天空光的线偏振度观测模拟,分析了线偏振度对FMF参数的波段敏感性,并基于仿真数据开展了算法的反演测试。研究结果表明:偏振测量在长波近红外波段对FMF的敏感性高于可见光波段;基于OE框架的FMF反演算法具有良好的闭合性;在地基天顶观测模式下,引入线偏振度测量参与反演能够有效提高FMF的反演精度,FMF反演误差从1.4%下降到了0.18%。最优化反演方法对于气溶胶遥感具有一定的潜力和可行性,有望成为提高PM2.5遥感监测能力的新途径。
基金National Natural Science Foundation of China(No.61163009)。
文摘Wireless sensor networks are extremely vulnerable to various security threats.The intrusion detection method based on game theory can effectively balance the detection rate and energy consumption of the system.The accurate analysis of the attack behavior of malicious sensor nodes can help to configure intrusion detection system,reduce unnecessary system consumption and improve detection efficiency.However,the completely rational assumption of the traditional game model will cause the established model to be inconsistent with the actual attack and defense scenario.In order to formulate a reasonable and effective intrusion detection strategy,we introduce evolutionary game theory to establish an attack evolution game model based on optimal response dynamics,and then analyze the attack behavior of malicious sensor nodes.Theoretical analysis and simulation results show that the evolution trend of attacks is closely related to the number of malicious sensors in the network and the initial state of the strategy,and the attacker can set the initial strategy so that all malicious sensor nodes will eventually launch attacks.Our work is of great significance to guide the development of defense strategies for intrusion detection systems.
基金supported by the Key Project National Science Foundation of China(No.91130004)the Natural Science Foundation of China(Nos.11171077,11331004)the National Talents Training Base for Basic Research and Teaching of Natural Science of China(No.J1103105)
文摘The problem for determining the exchange rate function of 2D CCPF model by measurements on the partial boundary is considered and solved as one PDE-constraint optimization problem. The optimal variant is the minimum of a cost functional that quantifies the difference between the measurements and the exact solutions. Gradientbased algorithm is used to solve this optimization problem. At each step, the derivative of the cost functional with respect to the exchange rate function is calculated and only one forward solution and one adjoint solution are needed. One method based on the adjoint equation is developed and implemented. Numerical examples show the efficiency of the adjoint method.
