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Determination of Gamma point source efficiency based on a backpropagation neural network 被引量:4
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作者 Hong-Long Zheng Xian-Guo Tuo +4 位作者 Shu-Ming Peng Rui Shi Huai-Liang Li Jing Lu Jin-Fu Li 《Nuclear Science and Techniques》 SCIE CAS CSCD 2018年第5期1-9,共9页
Efficiency is an important factor in quantitative and qualitative analysis of radionuclides, and the gamma point source efficiency is related to the radial angle,detection distance, and gamma-ray energy. In this work,... Efficiency is an important factor in quantitative and qualitative analysis of radionuclides, and the gamma point source efficiency is related to the radial angle,detection distance, and gamma-ray energy. In this work, on the basis of a back-propagation(BP) neural network model,a method to determine the gamma point source efficiency is developed and validated. The efficiency of the point sources ^(137)Cs and ^(60)Co at discrete radial angles, detection distances, and gamma-ray energies is measured, and the BP neural network prediction model is constructed using MATLAB. The gamma point source efficiencies at different radial angles, detection distances, and gamma-ray energies are predicted quickly and accurately using this nonlinear prediction model. The results show that the maximum error between the predicted and experimental values is 3.732% at 661.661 keV, 11π/24, and 35 cm, and those under other conditions are less than 3%. The gamma point source efficiencies obtained using the BP neural network model are in good agreement with experimental data. 展开更多
关键词 EFFICIENCY bp neural network HPGE DETECTOR GAMMA point source
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Study on analytical noise propagation in convolutional neural network methods used in computed tomography imaging 被引量:7
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作者 Xiao-Yue Guo Li Zhang Yu-Xiang Xing 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第6期114-127,共14页
Neural network methods have recently emerged as a hot topic in computed tomography(CT) imaging owing to their powerful fitting ability;however, their potential applications still need to be carefully studied because t... Neural network methods have recently emerged as a hot topic in computed tomography(CT) imaging owing to their powerful fitting ability;however, their potential applications still need to be carefully studied because their results are often difficult to interpret and are ambiguous in generalizability. Thus, quality assessments of the results obtained from a neural network are necessary to evaluate the neural network. Assessing the image quality of neural networks using traditional objective measurements is not appropriate because neural networks are nonstationary and nonlinear. In contrast, subjective assessments are trustworthy, although they are time-and energy-consuming for radiologists. Model observers that mimic subjective assessment require the mean and covariance of images, which are calculated from numerous image samples;however, this has not yet been applied to the evaluation of neural networks. In this study, we propose an analytical method for noise propagation from a single projection to efficiently evaluate convolutional neural networks(CNNs) in the CT imaging field. We propagate noise through nonlinear layers in a CNN using the Taylor expansion. Nesting of the linear and nonlinear layer noise propagation constitutes the covariance estimation of the CNN. A commonly used U-net structure is adopted for validation. The results reveal that the covariance estimation obtained from the proposed analytical method agrees well with that obtained from the image samples for different phantoms, noise levels, and activation functions, demonstrating that propagating noise from only a single projection is feasible for CNN methods in CT reconstruction. In addition, we use covariance estimation to provide three measurements for the qualitative and quantitative performance evaluation of U-net. The results indicate that the network cannot be applied to projections with high noise levels and possesses limitations in terms of efficiency for processing low-noise projections. U-net is more effective in improving the image quality of smooth regions compared with that of the edge. LeakyReLU outperforms Swish in terms of noise reduction. 展开更多
关键词 Noise propagation Convolutional neural network Image quality assessment
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Application of the Backpropagation Neural Network Method in Designing Tungsten Heavy Alloy
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作者 张朝晖 王玮洁 +1 位作者 王富耻 李树奎 《Journal of Beijing Institute of Technology》 EI CAS 2006年第4期478-482,共5页
The model describing the dependence of the mechanical properties on the chemical composition and as deformation techniques of tungsten heavy alloy is established by the method of improved the backpropagation neural ne... The model describing the dependence of the mechanical properties on the chemical composition and as deformation techniques of tungsten heavy alloy is established by the method of improved the backpropagation neural network. The mechanical properties' parameters of tungsten alloy and deformation techniques for tungsten alloy are used as the inputs. The chemical composition and deformation amount of tungsten alloy are used as the outputs. Then they are used for training the neural network. At the same time, the optimal number of the hidden neurons is obtained through the experiential equations, and the varied step learning method is adopted to ensure the stability of the training process. According to the requirements for mechanical properties, the chemical composition and the deformation condition for tungsten heavy alloy can be designed by this artificial neural network system. 展开更多
关键词 tungsten heavy alloy material design backpropagation bp neural network
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COMBINATION OF DISTRIBUTED KALMAN FILTER AND BP NEURAL NETWORK FOR ESG BIAS MODEL IDENTIFICATION 被引量:3
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作者 张克志 田蔚风 钱峰 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2010年第3期226-231,共6页
By combining the distributed Kalman filter (DKF) with the back propagation neural network (BPNN),a novel method is proposed to identify the bias of electrostatic suspended gyroscope (ESG). Firstly,the data sets ... By combining the distributed Kalman filter (DKF) with the back propagation neural network (BPNN),a novel method is proposed to identify the bias of electrostatic suspended gyroscope (ESG). Firstly,the data sets of multi-measurements of the same ESG in different noise environments are "mapped" into a sensor network,and DKF with embedded consensus filters is then used to preprocess the data sets. After transforming the preprocessed results into the trained input and the desired output of neural network,BPNN with the learning rate and the momentum term is further utilized to identify the ESG bias. As demonstrated in the experiment,the proposed approach is effective for the model identification of the ESG bias. 展开更多
关键词 model identification distributed Kalman filter(DKF) back propagation neural networkbpNN) electrostatic suspended gyroscope(ESG)
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Prediction of Injection-Production Ratio with BP Neural Network
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作者 袁爱武 郑晓松 王东城 《Petroleum Science》 SCIE CAS CSCD 2004年第4期62-65,共4页
Injection of water to enhance oil production is commonplace, and improvements in understanding the process are economically important. This study examines predictive models of the injection-to-production ratio. First... Injection of water to enhance oil production is commonplace, and improvements in understanding the process are economically important. This study examines predictive models of the injection-to-production ratio. Firstly, the error between the fitting and actual injection-production ratio is calculated with such methods as the injection-production ratio and water-oil ratio method, the material balance method, the multiple regression method, the gray theory GM (1,1) model and the back-propogation (BP) neural network method by computer applications in this paper. The relative average errors calculated are respectively 1.67%, 1.08%, 19.2%, 1.38% and 0.88%. Secondly, the reasons for the errors from different prediction methods are analyzed theoretically, indicating that the prediction precision of the BP neural network method is high, and that it has a better self-adaptability, so that it can reflect the internal relationship between the injection-production ratio and the influencing factors. Therefore, the BP neural network method is suitable to the prediction of injection-production ratio. 展开更多
关键词 Injection-production ratio (IPR) bp neural network gray theory PREDICTION
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基于PCA-BPNN的桥梁爆炸荷载时程预测
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作者 杜晓庆 何益平 +2 位作者 邱涛 程帅 张德志 《爆炸与冲击》 北大核心 2025年第3期77-91,共15页
人工智能方法是预测爆炸荷载的新手段,但现有方法主要用于预测爆炸冲击波的超压峰值或冲量,而用于预测反射超压时程的研究不多。针对这一问题,以平面冲击波绕射桥梁主梁为对象,提出了一种基于主成分分析(principal components analysis,... 人工智能方法是预测爆炸荷载的新手段,但现有方法主要用于预测爆炸冲击波的超压峰值或冲量,而用于预测反射超压时程的研究不多。针对这一问题,以平面冲击波绕射桥梁主梁为对象,提出了一种基于主成分分析(principal components analysis,PCA)和误差反向传播神经网络(backpropagation neural network,BPNN)的桥梁爆炸冲击波反射超压时程预测模型。该预测模型利用PCA降维处理时程数据,基于多任务学习的BPNN算法,提出了考虑超压峰值和冲量峰值影响的损失函数,使模型能有效预测不同入射超压下的桥梁冲击波荷载时程。通过分析多任务学习模型、多输入单输出模型和多输入多输出模型等3种BPNN模型,发现多任务学习模型的预测精度最高,而多输入多输出模型难以有效适应当前预测任务需求。采用多任务学习模型预测得到的桥梁表面各测点位置的反射超压时程、超压峰值精度较高,决定系数R2分别为0.792和0.987,作用在箱梁上的合力时程和扭矩时程预测值也与数值模拟值较为吻合。同时,该模型对内插值预测的表现优于外推值预测,但其在预测外推值方面同样展现出了一定的能力。 展开更多
关键词 爆炸荷载预测 反射超压时程 误差反向传播神经网络 主成分分析 多任务学习
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基于BP神经网络的咸水黏度预测及其对渗流的影响
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作者 李涛 美合日阿依·穆太力普 +2 位作者 薛福生 李延静 敬嘉珩 《油气地质与采收率》 北大核心 2025年第1期152-161,共10页
在碳中和背景下,采用CO_(2)咸水层封存技术来实现碳减排目标时,咸水黏度对储层中的CO_(2)-咸水两相渗流过程有着直接的影响。目前,基于压力影响的黏度预测方法仍有待完善。使用最小二乘法、BP神经网络和基于遗传算法的BP神经网络,将咸... 在碳中和背景下,采用CO_(2)咸水层封存技术来实现碳减排目标时,咸水黏度对储层中的CO_(2)-咸水两相渗流过程有着直接的影响。目前,基于压力影响的黏度预测方法仍有待完善。使用最小二乘法、BP神经网络和基于遗传算法的BP神经网络,将咸水黏度分别当作温度、质量摩尔浓度的二元函数以及温度、质量摩尔浓度、压力的三元函数优化了现有的计算方法,建立了考虑压力影响的黏度预测优化模型。在获得最佳的预测方式后,基于COMSOL软件的水平集方法系统分析了黏度对渗流的影响。研究结果表明,采用最小二乘法可以对现有的经验公式进行一定优化,但是效果不明显;采用二元BP神经网络可以将预测精度提高45.20%,考虑压力后采用三元BP神经网络可以将预测精度提高57.32%。因此,在实验数据充足的情况下,基于BP神经网络模型可以得到较大压力范围内可靠的咸水黏度值;由于经验公式法能够预测黏度变化趋势,在缺乏相应实验数据的情况下,可通过经验公式法获得咸水黏度值。此外,通过仿真结果可以发现,黏度会影响流体在流道的分布,进而影响流动速度,黏度比越大,出口平均速度波动越小且更快地趋于平稳;而且黏度比越大,残余水饱和度越小,越有利于驱替过程的进行,二者呈对数函数的关系。 展开更多
关键词 咸水黏度 bp神经网络 压力 渗流模拟 CO_(2)咸水层封存
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PCA-BP神经网络模型在拖拉机发动机故障诊断中的应用
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作者 杨健 《农机化研究》 北大核心 2025年第3期254-258,共5页
拖拉机发动机故障诊断是指通过对拖拉机发动机的运行状态、传感器数据等信息进行分析和处理,识别出发动机故障的类型和位置,及时准确地诊断拖拉机发动机故障,对于提高农机装备的使用效率和经济效益具有重要的意义。为此,基于主成分分析(... 拖拉机发动机故障诊断是指通过对拖拉机发动机的运行状态、传感器数据等信息进行分析和处理,识别出发动机故障的类型和位置,及时准确地诊断拖拉机发动机故障,对于提高农机装备的使用效率和经济效益具有重要的意义。为此,基于主成分分析(PCA)算法对拖拉机发动机的传感器数据进行降维处理,并使用BP神经网络对降维后的数据进行分类识别,以实现拖拉机发动机故障的诊断。试验结果表明:PCA-BP神经网络模型可以准确地诊断拖拉机发动机的多种故障,相比于传统的BP神经网络模型,具有更高的准确率和更好的泛化能力,表明PCA-BP神经网络模型在拖拉机发动机故障诊断中具有较大的应用前景。 展开更多
关键词 拖拉机发动机 故障诊断 主成分分析 bp神经网络
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基于BP神经网络结合ERA5数据的风电功率预测
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作者 王婷婷 李斯胜 +4 位作者 于伟 能锋田 李星南 杨佳琳 熊亮 《储能科学与技术》 北大核心 2025年第1期183-189,共7页
随着我国风力发电技术的不断发展和完善,风电在电力系统运行和调度的作用越来越突出。为了高效准确地预测风电功率,减少大量风电入网带来的负面影响,本文基于BP神经网络结合ERA5数据对我国北方某风电场进行风电功率预测,并采用粒子群优... 随着我国风力发电技术的不断发展和完善,风电在电力系统运行和调度的作用越来越突出。为了高效准确地预测风电功率,减少大量风电入网带来的负面影响,本文基于BP神经网络结合ERA5数据对我国北方某风电场进行风电功率预测,并采用粒子群优化(particle swarm algorithm,PSO)算法优化模型,结合平均绝对误差、均方根误差和Pearson相关系数分析风电功率预测效果。结果表明,模型训练集中预测与实测风电功率变化趋势基本一致,呈现同增同减的趋势,BP模型的平均绝对误差为702.12 W,均方根误差为1000.18 W,相关系数为0.91,PSO-BP模型的平均绝对误差为700.75 W,均方根误差为995.16 W,相关系数为0.94;测试集中ERA5数据在一定程度上高估了风电功率,但整体趋势基本一致,BP模型的平均绝对误差为861.09 W,均方根误差为1150.86 W,相关系数为0.81;PSO-BP模型的平均绝对误差为829.55 W,均方根误差为1117.39 W,相关系数为0.83,模型的预测效果相对较好,PSO-BP模型相较于BP模型的预测效果均有一定程度的提高,在该区域的风电功率预测方面有较好的适用性。研究结果可为缺乏观测数据或观测数据质量不高的地区预测风电功率提供参考。 展开更多
关键词 风力发电 bp神经网络 ERA5再分析资料 粒子群优化算法 风电功率预测
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改进SSA优化BP神经网络的变压器故障诊断
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作者 汪繁荣 汪筠涵 江俊杰 《现代电子技术》 北大核心 2025年第4期145-150,共6页
变压器故障类型的准确诊断对保障电网的安全与稳定至关重要。针对BP神经网络与麻雀搜索算法(SSA)存在收敛缓慢和易陷入局部极值导致无法准确诊断的问题,提出将改进的麻雀搜索算法(ISSA)优化BP神经网络应用于变压器故障诊断。首先,引入... 变压器故障类型的准确诊断对保障电网的安全与稳定至关重要。针对BP神经网络与麻雀搜索算法(SSA)存在收敛缓慢和易陷入局部极值导致无法准确诊断的问题,提出将改进的麻雀搜索算法(ISSA)优化BP神经网络应用于变压器故障诊断。首先,引入非线性惯性权重和纵横交叉策略,从而提高算法的收敛速度和全局寻优能力;其次,将ISSA与传统SSA在收敛函数上进行对比分析,得到ISSA算法在迭代12次后以52%的准确率收敛,而SSA算法迭代23次后才达到25%的准确率,证明了ISSA在收敛速度和精度方面有明显提高;最后,将ISSA-BP、SSA-BP和BP诊断模型进行对比。实验结果表明,ISSA-BP模型准确率达到了97%,比SSA-BP、BP神经网络模型分别提高了4%和11%,可以认为提出的算法模型在变压器故障诊断领域具有更高的精度与良好的发展前景。 展开更多
关键词 麻雀搜索算法 bp神经网络 变压器 故障诊断 非线性惯性权重 纵横交叉策略
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BP神经网络在离心压缩机叶轮优化中的应用
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作者 董志强 于根亮 +1 位作者 董逸飞 陈义恒 《汽车实用技术》 2025年第2期56-62,共7页
为了提高离心式压缩机叶轮设计效率并降低计算资源消耗,针对遗传算法优化中计算量大、效率低的问题,提出基于改进粒子群优化算法(IPSO)优化BP神经网络的方法。通过少量计算流体动力学(CFD)仿真样本,训练BP神经网络建立效率与叶轮参数的... 为了提高离心式压缩机叶轮设计效率并降低计算资源消耗,针对遗传算法优化中计算量大、效率低的问题,提出基于改进粒子群优化算法(IPSO)优化BP神经网络的方法。通过少量计算流体动力学(CFD)仿真样本,训练BP神经网络建立效率与叶轮参数的映射关系,结合IPSO优化其参数,同时利用遗传算法(GA)确定叶轮的最佳性能参数。研究表明,改进的IPSO算法通过增强粒子群的动态适应性和全局搜索能力,提高了BP神经网络的预测精度和优化效率。优化后的叶轮等熵效率提高1.34%,多变效率提高1.04%,流量增加10.4%。该方法显著提升了离心式压缩机叶轮的设计效率和性能,为复杂流体机械的优化设计提供了新思路。 展开更多
关键词 离心式压缩机 CFD仿真 叶轮参数优化 bp神经网络 遗传算法
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基于BP神经网络的机制砂混凝土抗压强度预测
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作者 张军 崔政新 +1 位作者 裘松立 宋冰泉 《建筑技术》 2025年第1期88-92,共5页
机制砂混凝土强度影响因素复杂,收集国内外权威文献试验数据建立了162组机制砂抗压强度的数据库,利用BP神经网络对机制砂混凝土抗压强度进行预测。采用多层反向传播算法对人工神经网络模型进行训练并预测,发现BP神经网络模型具有良好的... 机制砂混凝土强度影响因素复杂,收集国内外权威文献试验数据建立了162组机制砂抗压强度的数据库,利用BP神经网络对机制砂混凝土抗压强度进行预测。采用多层反向传播算法对人工神经网络模型进行训练并预测,发现BP神经网络模型具有良好的预测和泛化能力,模型的预测值与实测值高度吻合;基于BP神经网络模型分析了石粉含量对机制砂混凝土不同强度等级的影响,发现石粉含量约10%时达到最大值,预测值与实际值的误差在8%以内。深度学习方法可有效提高机制砂混凝土配合比设计的试验效率,降低材料和时间成本。 展开更多
关键词 机制砂混凝土 抗压强度 bp神经网络 石粉含量 配合比设计
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基于高斯过程回归和BP神经网络的油储地罐容积表标定研究
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作者 王彩玲 程叶 +1 位作者 许欣黎 倪庆旭 《石油石化节能与计量》 2025年第2期26-30,35,共6页
石油作为中国重要的能源资源之一,广泛应用于发电、运输、工业生产等各个领域。准确的油储地罐容积表标定对于确保各类石油产品储存、运输和交易的精确计量至关重要。传统的标定方法通常高度依赖于静态测量和经验公式,易受时间、环境条... 石油作为中国重要的能源资源之一,广泛应用于发电、运输、工业生产等各个领域。准确的油储地罐容积表标定对于确保各类石油产品储存、运输和交易的精确计量至关重要。传统的标定方法通常高度依赖于静态测量和经验公式,易受时间、环境条件及人为因素的影响。为了解决这一问题,提出了一种基于高斯过程回归(GPR)和反向传播神经网络(BPNN)的标定验证方法。在真实加油站数据构建的数据集上进行实验,结果显示,高斯过程回归模型和BP神经网络模型的平均均方根误差RMSE分别为3.435、8.409,模型的预测效果相对较好,研究结果可为容积表的标定工作提供有价值的参考。 展开更多
关键词 容积表标定 bp神经网络 高斯过程回归 数据挖掘 误差预测
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GA-BP模型在HSS模型参数取值中的应用
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作者 张杰 马杰 +2 位作者 陈啸海 钟鹏 王营营 《城市道桥与防洪》 2025年第1期229-235,共7页
小应变硬化土(HSS)模型可以有效反映土的压缩硬化特性和小应变特性,非常适合黄土基坑的数值模拟计算。但是,HSS模型包含了11个硬化土(HS)模型参数和2个小应变参数,而这2个小应变参数往往需要采用试验方法确定,获取过程复杂。为了探讨小... 小应变硬化土(HSS)模型可以有效反映土的压缩硬化特性和小应变特性,非常适合黄土基坑的数值模拟计算。但是,HSS模型包含了11个硬化土(HS)模型参数和2个小应变参数,而这2个小应变参数往往需要采用试验方法确定,获取过程复杂。为了探讨小应变参数的预测方法,采用经过遗传算法优化的BP神经网络模型,即GA-BP神经网络模型,首先根据预设的小应变参数水平经过数值模拟计算得到49组位移数据,然后将得到的数据用于GA-BP神经网络的训练,待GA-BP神经网络的预测误差达到要求之后,再使用实际的位移数据反演得到小应变参数,最后基于预测得到的小应变参数进行数值模拟。结果显示,GA-BP神经网络模型预测的小应变参数在基坑围护结构最大水平位移和地表最大沉降计算方面表现良好,可以应用于实际工程。 展开更多
关键词 岩土工程 遗传算法 HSS模型 bp神经网络 小应变参数 参数反演
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Trajectory tracking guidance of interceptor via prescribed performance integral sliding mode with neural network disturbance observer 被引量:1
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作者 Wenxue Chen Yudong Hu +1 位作者 Changsheng Gao Ruoming An 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第2期412-429,共18页
This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance system... This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance systems of missiles is challenging.As our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy.The global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional PPF.Then,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities.Meanwhile,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify disturbances.The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots. 展开更多
关键词 bp network neural Integral sliding mode control(ISMC) Missile defense Prescribed performance function(PPF) State observer Tracking guidance system
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DDoS Attack Detection Scheme Based on Entropy and PSO-BP Neural Network in SDN 被引量:8
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作者 Zhenpeng Liu Yupeng He +1 位作者 Wensheng Wang Bin Zhang 《China Communications》 SCIE CSCD 2019年第7期144-155,共12页
SDN (Software Defined Network) has many security problems, and DDoS attack is undoubtedly the most serious harm to SDN architecture network. How to accurately and effectively detect DDoS attacks has always been a diff... SDN (Software Defined Network) has many security problems, and DDoS attack is undoubtedly the most serious harm to SDN architecture network. How to accurately and effectively detect DDoS attacks has always been a difficult point and focus of SDN security research. Based on the characteristics of SDN, a DDoS attack detection method combining generalized entropy and PSOBP neural network is proposed. The traffic is pre-detected by the generalized entropy method deployed on the switch, and the detection result is divided into normal and abnormal. Locate the switch that issued the abnormal alarm. The controller uses the PSO-BP neural network to detect whether a DDoS attack occurs by further extracting the flow features of the abnormal switch. Experiments show that compared with other methods, the detection accurate rate is guaranteed while the CPU load of the controller is reduced, and the detection capability is better. 展开更多
关键词 software-defined networkING distributed DENIAL of service ATTACKS generalized information ENTROPY particle SWARM optimization back propagation neural network ATTACK detection
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A Human Body Posture Recognition Algorithm Based on BP Neural Network for Wireless Body Area Networks 被引量:10
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作者 Fengye Hu Lu Wang +2 位作者 Shanshan Wang Xiaolan Liu Gengxin He 《China Communications》 SCIE CSCD 2016年第8期198-208,共11页
Human body posture recognition has attracted considerable attention in recent years in wireless body area networks(WBAN). In order to precisely recognize human body posture,many recognition algorithms have been propos... Human body posture recognition has attracted considerable attention in recent years in wireless body area networks(WBAN). In order to precisely recognize human body posture,many recognition algorithms have been proposed.However, the recognition rate is relatively low. In this paper, we apply back propagation(BP) neural network as a classifier to recognizing human body posture, where signals are collected from VG350 acceleration sensor and a posture signal collection system based on WBAN is designed. Human body signal vector magnitude(SVM) and tri-axial acceleration sensor data are used to describe the human body postures. We are able to recognize 4postures: Walk, Run, Squat and Sit. Our posture recognition rate is up to 91.67%. Furthermore, we find an implied relationship between hidden layer neurons and the posture recognition rate. The proposed human body posture recognition algorithm lays the foundation for the subsequent applications. 展开更多
关键词 wireless body area networks bp neural network signal vector magnitude posture recognition rate
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BP neural networks and random forest models to detect damage by Dendrolimus punctatus Walker 被引量:7
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作者 Zhanghua Xu Xuying Huang +4 位作者 Lu Lin Qianfeng Wang Jian Liu Kunyong Yu Chongcheng Chen 《Journal of Forestry Research》 SCIE CAS CSCD 2020年第1期107-121,共15页
The construction of a pest detection algorithm is an important step to couple"ground-space"characteristics,which is also the basis for rapid and accurate monitoring and detection of pest damage.In four exper... The construction of a pest detection algorithm is an important step to couple"ground-space"characteristics,which is also the basis for rapid and accurate monitoring and detection of pest damage.In four experimental areas in Sanming City,Jiangle County,Sha County and Yanping District in Fujian Province,sample data on pest damage in 182 sets of Dendrolimus punctatus were collected.The data were randomly divided into a training set and testing set,and five duplicate tests and one eliminating-indicator test were done.Based on the characterization analysis of the host for D.punctatus damage,seven characteristic indicators of ground and remote sensing including leaf area index,standard error of leaf area index(SEL)of pine forest,normalized difference vegetation index(NDVI),wetness from tasseled cap transformation(WET),green band(B2),red band(B3),near-infrared band(B4)of remote sensing image are obtained to construct BP neural networks and random forest models of pest levels.The detection results of these two algorithms were comprehensively compared from the aspects of detection precision,kappa coefficient,receiver operating characteristic curve,and a paired t test.The results showed that the seven indicators all were responsive to pest damage,and NDVI was relatively weak;the average pest damage detection precision of six tests by BP neural networks was 77.29%,the kappa coefficient was 0.6869 and after the RF algorithm,the respective values were 79.30%and 0.7151,showing that the latter is more optimized,but there was no significant difference(p>0.05);the detection precision,kappa coefficient and AUC of the RF algorithm was higher than the BP neural networks for three pest levels(no damage,moderate damage and severe damage).The detection precision and AUC of BP neural networks were a little higher for mild damage,but the difference was not significant(p>0.05)except for the kappa coefficient for the no damage level(p<0.05).An"over-fitting"phenomenon tends to occur in BP neural networks,while RF method is more robust,providing a detection effect that is better than the BP neural networks.Thus,the application of the random forest algorithm for pest damage and multilevel dispersed variables is thus feasible and suggests that attention to the proportionality of sample data from various categories is needed when collecting data. 展开更多
关键词 bp neural networks Detection precision Kappa coefficient Pine moth Random forest ROC curve
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An Image Encryption Algorithm Based on BP Neural Network and Hyperchaotic System 被引量:9
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作者 Feifei Yang Jun Mou +1 位作者 Yinghong Cao Ran Chu 《China Communications》 SCIE CSCD 2020年第5期21-28,共8页
To reduce the bandwidth and storage resources of image information in communication transmission, and improve the secure communication of information. In this paper, an image compression and encryption algorithm based... To reduce the bandwidth and storage resources of image information in communication transmission, and improve the secure communication of information. In this paper, an image compression and encryption algorithm based on fractional-order memristive hyperchaotic system and BP neural network is proposed. In this algorithm, the image pixel values are compressed by BP neural network, the chaotic sequences of the fractional-order memristive hyperchaotic system are used to diffuse the pixel values. The experimental simulation results indicate that the proposed algorithm not only can effectively compress and encrypt image, but also have better security features. Therefore, this work provides theoretical guidance and experimental basis for the safe transmission and storage of image information in practical communication. 展开更多
关键词 bp neural network fractional-order hyperchaotic system image encryption algorithm secure communication
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Distributed Resource Allocation in Ultra-Dense Networks via Belief Propagation 被引量:2
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作者 CHEN Siyi XING Chengwen FEI Zesong 《China Communications》 SCIE CSCD 2015年第11期79-91,共13页
Ultra-dense networking is widely accepted as a promising enabling technology to realize high power and spectrum efficient communications in future 5G communication systems. Although joint resource allocation schemes p... Ultra-dense networking is widely accepted as a promising enabling technology to realize high power and spectrum efficient communications in future 5G communication systems. Although joint resource allocation schemes promise huge performance improvement at the cost of cooperation among base stations,the large numbers of user equipment and base station make jointly optimizing the available resource very challenging and even prohibitive. How to decompose the resource allocation problem is a critical issue. In this paper,we exploit factor graphs to design a distributed resource allocation algorithm for ultra dense networks,which consists of power allocation,subcarrier allocation and cell association. The proposed factor graph based distributed algorithm can decompose the joint optimization problem of resource allocation into a series of low complexity subproblems with much lower dimensionality,and the original optimization problem can be efficiently solved via solving these subproblems iteratively. In addition,based on the proposed algorithm the amounts of exchanging information overhead between the resulting subprob-lems are also reduced. The proposed distributed algorithm can be understood as solving largely dimensional optimization problem in a soft manner,which is much preferred in practical scenarios. Finally,the performance of the proposed low complexity distributed algorithm is evaluated by several numerical results. 展开更多
关键词 RESOURCE ALLOCATION distributed optimization BELIEF propagation(bp) ultradense network
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