When the maneuverability of a pursuer is not significantly higher than that of an evader,it will be difficult to intercept the evader with only one pursuer.Therefore,this article adopts a two-to-one differential game ...When the maneuverability of a pursuer is not significantly higher than that of an evader,it will be difficult to intercept the evader with only one pursuer.Therefore,this article adopts a two-to-one differential game strategy,the game of kind is generally considered to be angle-optimized,which allows unlimited turns,but these practices do not take into account the effect of acceleration,which does not correspond to the actual situation,thus,based on the angle-optimized,the acceleration optimization and the acceleration upper bound constraint are added into the game for consideration.A two-to-one differential game problem is proposed in the three-dimensional space,and an improved multi-objective grey wolf optimization(IMOGWO)algorithm is proposed to solve the optimal game point of this problem.With the equations that describe the relative motions between the pursuers and the evader in the three-dimensional space,a multi-objective function with constraints is given as the performance index to design an optimal strategy for the differential game.Then the optimal game point is solved by using the IMOGWO algorithm.It is proved based on Markov chains that with the IMOGWO,the Pareto solution set is the solution of the differential game.Finally,it is verified through simulations that the pursuers can capture the escapee,and via comparative experiments,it is shown that the IMOGWO algorithm performs well in terms of running time and memory usage.展开更多
With the development of high energy solid propellants,it is critical to evaluate the safety and power performance of solid propellants in the face of threats such as unmanned aerial vehicles(UAVs)when transporting and...With the development of high energy solid propellants,it is critical to evaluate the safety and power performance of solid propellants in the face of threats such as unmanned aerial vehicles(UAVs)when transporting and using them in contemporary warfare.An electric probe-type cylinder test measured the displacement-time behavior of NEPE high-energy solid propellant,and the parameters of the Jones-Wilkins-Lee(JWL)equation of state(EOS)were derived using particle swarm optimization(PSO)with the Gurney energy model.Further,the parameters of JWL-Miller EOS,determined through AUTODYN simulations,were validated by comparing airburst process simulations with experimental overpressure data.The study established a method for determining EOS parameters of high-energy propellants,achieving a high degree of accuracy.The derived parameters ensure precise modeling of propellant behavior,offering a reliable foundation for future applications in solid rocket motor performance optimization and safety assessment.展开更多
This study proposed a new and more flexible S-shaped rock damage evolution model from a phenomenological perspective based on an improved Logistic function to describe the characteristics of the rock strain softening ...This study proposed a new and more flexible S-shaped rock damage evolution model from a phenomenological perspective based on an improved Logistic function to describe the characteristics of the rock strain softening and damage process.Simultaneously,it established a constitutive model capable of describing the entire process of rock pre-peak compaction and post-peak strain softening deformation,considering the nonlinear effects of the initial compaction stage of rocks,combined with damage mechanics theory and effective medium theory.In addition,this research verified the rationality of the constructed damage constitutive model using results from uniaxial and conventional triaxial compression tests on Miluo granite,yellow sandstone,mudstone,and glutenite.The results indicate that based on the improved Logistic function,the theoretical damage model accurately describes the entire evolution of damage characteristics during rock compression deformation,from maintenance through gradual onset,accelerated development to deceleration and termination,in a simple and unified expression.At the same time,the constructed constitutive model can accurately simulate the stress-strain process of different rock types under uniaxial and conventional triaxial compression,and the theoretical model curve closely aligns with experimental data.Compared to existing constitutive models,the proposed model has significant advantages.The damage model parameters a,r and β have clear physical meanings and interact competitively,where the three parameters collectively determine the shape of the theoretical stress−strain curve.展开更多
In the field of calculating the attack area of air-to-air missiles in modern air combat scenarios,the limitations of existing research,including real-time calculation,accuracy efficiency trade-off,and the absence of t...In the field of calculating the attack area of air-to-air missiles in modern air combat scenarios,the limitations of existing research,including real-time calculation,accuracy efficiency trade-off,and the absence of the three-dimensional attack area model,restrict their practical applications.To address these issues,an improved backtracking algorithm is proposed to improve calculation efficiency.A significant reduction in solution time and maintenance of accuracy in the three-dimensional attack area are achieved by using the proposed algorithm.Furthermore,the age-layered population structure genetic programming(ALPS-GP)algorithm is introduced to determine an analytical polynomial model of the three-dimensional attack area,considering real-time requirements.The accuracy of the polynomial model is enhanced through the coefficient correction using an improved gradient descent algorithm.The study reveals a remarkable combination of high accuracy and efficient real-time computation,with a mean error of 91.89 m using the analytical polynomial model of the three-dimensional attack area solved in just 10^(-4)s,thus meeting the requirements of real-time combat scenarios.展开更多
由于患者个体差异、采集协议多样性和数据损坏等因素,现有基于磁共振成像(Magnetic resonance imaging,MRI)的脑肿瘤分割方法存在模态数据丢失问题,导致分割精度不高。为此,本文提出了一种基于U-Net和Transformer结合的不完整多模态脑...由于患者个体差异、采集协议多样性和数据损坏等因素,现有基于磁共振成像(Magnetic resonance imaging,MRI)的脑肿瘤分割方法存在模态数据丢失问题,导致分割精度不高。为此,本文提出了一种基于U-Net和Transformer结合的不完整多模态脑肿瘤分割(Incomplete multimodal brain tumor segmentation based on the combination of U-Net and Transformer,IM TransNet)方法。首先,针对脑肿瘤MRI的4个不同模态设计了单模态特定编码器,提升模型对各模态数据的表征能力。其次,在U-Net中嵌入双重注意力的Transformer模块,克服模态缺失引起的信息不完整问题,减少U-Net的长距离上下文交互和空间依赖性局限。在U-Net的跳跃连接中加入跳跃交叉注意力机制,动态关注不同层级和模态的特征,即使在模态缺失时,也能有效融合特征并进行重建。此外,针对模态缺失引起的训练不平衡问题,设计了辅助解码模块,确保模型在各种不完整模态子集上均能稳定高效地分割脑肿瘤。最后,基于公开数据集BRATS验证模型的性能。实验结果表明,本文提出的模型在增强型肿瘤、肿瘤核心和全肿瘤上的平均Dice评分分别为63.19%、76.42%和86.16%,证明了其在处理不完整多模态数据时的优越性和稳定性,为临床实践中脑肿瘤的准确、高效和可靠分割提供了一种可行的技术手段。展开更多
Offboard active decoys(OADs)can effectively jam monopulse radars.However,for missiles approaching from a particular direction and distance,the OAD should be placed at a specific location,posing high requirements for t...Offboard active decoys(OADs)can effectively jam monopulse radars.However,for missiles approaching from a particular direction and distance,the OAD should be placed at a specific location,posing high requirements for timing and deployment.To improve the response speed and jamming effect,a cluster of OADs based on an unmanned surface vehicle(USV)is proposed.The formation of the cluster determines the effectiveness of jamming.First,based on the mechanism of OAD jamming,critical conditions are identified,and a method for assessing the jamming effect is proposed.Then,for the optimization of the cluster formation,a mathematical model is built,and a multi-tribe adaptive particle swarm optimization algorithm based on mutation strategy and Metropolis criterion(3M-APSO)is designed.Finally,the formation optimization problem is solved and analyzed using the 3M-APSO algorithm under specific scenarios.The results show that the improved algorithm has a faster convergence rate and superior performance as compared to the standard Adaptive-PSO algorithm.Compared with a single OAD,the optimal formation of USV-OAD cluster effectively fills the blind area and maximizes the use of jamming resources.展开更多
为使桥梁病害检测更加高效、客观和智能,提出一种自动识别并定量计算混凝土病害尺寸的方法。该方法采用视觉几何组网络(Visual Geometry Group Network,VGG)作为U形网络(U-Net)的主干网络,对混凝土病害(剥落、裂缝和露筋)图像进行语义分...为使桥梁病害检测更加高效、客观和智能,提出一种自动识别并定量计算混凝土病害尺寸的方法。该方法采用视觉几何组网络(Visual Geometry Group Network,VGG)作为U形网络(U-Net)的主干网络,对混凝土病害(剥落、裂缝和露筋)图像进行语义分割,采用数学形态学算法对图像中的病害区域进行优化。通过MATLAB软件计算得到优化后的分割图像中病害区域像素点的数量,并利用参照物标定出图像中单个像素点的尺寸,计算得到混凝土病害的面积(或长度)。采用该方法对河南省许昌市17座现役钢筋混凝土桥梁病害图像进行语义分割实验。结果表明:U-Net能以较高的精度对复杂背景下混凝土桥梁多类病害进行像素级的分类,类别平均像素准确率为90.53%,平均交并比为80.54%。使用数学形态学对语义分割图像进行优化后,计算精度明显提高,优化后的误差绝对值为0.08%~0.21%。展开更多
基金National Natural Science Foundation of China(NSFC61773142,NSFC62303136)。
文摘When the maneuverability of a pursuer is not significantly higher than that of an evader,it will be difficult to intercept the evader with only one pursuer.Therefore,this article adopts a two-to-one differential game strategy,the game of kind is generally considered to be angle-optimized,which allows unlimited turns,but these practices do not take into account the effect of acceleration,which does not correspond to the actual situation,thus,based on the angle-optimized,the acceleration optimization and the acceleration upper bound constraint are added into the game for consideration.A two-to-one differential game problem is proposed in the three-dimensional space,and an improved multi-objective grey wolf optimization(IMOGWO)algorithm is proposed to solve the optimal game point of this problem.With the equations that describe the relative motions between the pursuers and the evader in the three-dimensional space,a multi-objective function with constraints is given as the performance index to design an optimal strategy for the differential game.Then the optimal game point is solved by using the IMOGWO algorithm.It is proved based on Markov chains that with the IMOGWO,the Pareto solution set is the solution of the differential game.Finally,it is verified through simulations that the pursuers can capture the escapee,and via comparative experiments,it is shown that the IMOGWO algorithm performs well in terms of running time and memory usage.
基金supported by"the Fundamental Research Funds for the Central Universities",No.30924010503.
文摘With the development of high energy solid propellants,it is critical to evaluate the safety and power performance of solid propellants in the face of threats such as unmanned aerial vehicles(UAVs)when transporting and using them in contemporary warfare.An electric probe-type cylinder test measured the displacement-time behavior of NEPE high-energy solid propellant,and the parameters of the Jones-Wilkins-Lee(JWL)equation of state(EOS)were derived using particle swarm optimization(PSO)with the Gurney energy model.Further,the parameters of JWL-Miller EOS,determined through AUTODYN simulations,were validated by comparing airburst process simulations with experimental overpressure data.The study established a method for determining EOS parameters of high-energy propellants,achieving a high degree of accuracy.The derived parameters ensure precise modeling of propellant behavior,offering a reliable foundation for future applications in solid rocket motor performance optimization and safety assessment.
基金Project(52074299)supported by the National Natural Science Foundation of ChinaProjects(2023JCCXSB02,BBJ2024083)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This study proposed a new and more flexible S-shaped rock damage evolution model from a phenomenological perspective based on an improved Logistic function to describe the characteristics of the rock strain softening and damage process.Simultaneously,it established a constitutive model capable of describing the entire process of rock pre-peak compaction and post-peak strain softening deformation,considering the nonlinear effects of the initial compaction stage of rocks,combined with damage mechanics theory and effective medium theory.In addition,this research verified the rationality of the constructed damage constitutive model using results from uniaxial and conventional triaxial compression tests on Miluo granite,yellow sandstone,mudstone,and glutenite.The results indicate that based on the improved Logistic function,the theoretical damage model accurately describes the entire evolution of damage characteristics during rock compression deformation,from maintenance through gradual onset,accelerated development to deceleration and termination,in a simple and unified expression.At the same time,the constructed constitutive model can accurately simulate the stress-strain process of different rock types under uniaxial and conventional triaxial compression,and the theoretical model curve closely aligns with experimental data.Compared to existing constitutive models,the proposed model has significant advantages.The damage model parameters a,r and β have clear physical meanings and interact competitively,where the three parameters collectively determine the shape of the theoretical stress−strain curve.
基金National Natural Science Foundation of China(62373187)Forward-looking Layout Special Projects(ILA220591A22)。
文摘In the field of calculating the attack area of air-to-air missiles in modern air combat scenarios,the limitations of existing research,including real-time calculation,accuracy efficiency trade-off,and the absence of the three-dimensional attack area model,restrict their practical applications.To address these issues,an improved backtracking algorithm is proposed to improve calculation efficiency.A significant reduction in solution time and maintenance of accuracy in the three-dimensional attack area are achieved by using the proposed algorithm.Furthermore,the age-layered population structure genetic programming(ALPS-GP)algorithm is introduced to determine an analytical polynomial model of the three-dimensional attack area,considering real-time requirements.The accuracy of the polynomial model is enhanced through the coefficient correction using an improved gradient descent algorithm.The study reveals a remarkable combination of high accuracy and efficient real-time computation,with a mean error of 91.89 m using the analytical polynomial model of the three-dimensional attack area solved in just 10^(-4)s,thus meeting the requirements of real-time combat scenarios.
文摘由于患者个体差异、采集协议多样性和数据损坏等因素,现有基于磁共振成像(Magnetic resonance imaging,MRI)的脑肿瘤分割方法存在模态数据丢失问题,导致分割精度不高。为此,本文提出了一种基于U-Net和Transformer结合的不完整多模态脑肿瘤分割(Incomplete multimodal brain tumor segmentation based on the combination of U-Net and Transformer,IM TransNet)方法。首先,针对脑肿瘤MRI的4个不同模态设计了单模态特定编码器,提升模型对各模态数据的表征能力。其次,在U-Net中嵌入双重注意力的Transformer模块,克服模态缺失引起的信息不完整问题,减少U-Net的长距离上下文交互和空间依赖性局限。在U-Net的跳跃连接中加入跳跃交叉注意力机制,动态关注不同层级和模态的特征,即使在模态缺失时,也能有效融合特征并进行重建。此外,针对模态缺失引起的训练不平衡问题,设计了辅助解码模块,确保模型在各种不完整模态子集上均能稳定高效地分割脑肿瘤。最后,基于公开数据集BRATS验证模型的性能。实验结果表明,本文提出的模型在增强型肿瘤、肿瘤核心和全肿瘤上的平均Dice评分分别为63.19%、76.42%和86.16%,证明了其在处理不完整多模态数据时的优越性和稳定性,为临床实践中脑肿瘤的准确、高效和可靠分割提供了一种可行的技术手段。
基金the National Natural Science Foundation of China(Grant No.62101579).
文摘Offboard active decoys(OADs)can effectively jam monopulse radars.However,for missiles approaching from a particular direction and distance,the OAD should be placed at a specific location,posing high requirements for timing and deployment.To improve the response speed and jamming effect,a cluster of OADs based on an unmanned surface vehicle(USV)is proposed.The formation of the cluster determines the effectiveness of jamming.First,based on the mechanism of OAD jamming,critical conditions are identified,and a method for assessing the jamming effect is proposed.Then,for the optimization of the cluster formation,a mathematical model is built,and a multi-tribe adaptive particle swarm optimization algorithm based on mutation strategy and Metropolis criterion(3M-APSO)is designed.Finally,the formation optimization problem is solved and analyzed using the 3M-APSO algorithm under specific scenarios.The results show that the improved algorithm has a faster convergence rate and superior performance as compared to the standard Adaptive-PSO algorithm.Compared with a single OAD,the optimal formation of USV-OAD cluster effectively fills the blind area and maximizes the use of jamming resources.
文摘为使桥梁病害检测更加高效、客观和智能,提出一种自动识别并定量计算混凝土病害尺寸的方法。该方法采用视觉几何组网络(Visual Geometry Group Network,VGG)作为U形网络(U-Net)的主干网络,对混凝土病害(剥落、裂缝和露筋)图像进行语义分割,采用数学形态学算法对图像中的病害区域进行优化。通过MATLAB软件计算得到优化后的分割图像中病害区域像素点的数量,并利用参照物标定出图像中单个像素点的尺寸,计算得到混凝土病害的面积(或长度)。采用该方法对河南省许昌市17座现役钢筋混凝土桥梁病害图像进行语义分割实验。结果表明:U-Net能以较高的精度对复杂背景下混凝土桥梁多类病害进行像素级的分类,类别平均像素准确率为90.53%,平均交并比为80.54%。使用数学形态学对语义分割图像进行优化后,计算精度明显提高,优化后的误差绝对值为0.08%~0.21%。
