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Gradient Descent Algorithm for Small UAV Parameter Estimation System
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作者 Guo Jiandong Liu Qingwen Wang Kang 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2017年第6期680-687,共8页
A gradient descent algorithm with adjustable parameter for attitude estimation is developed,aiming at the attitude measurement for small unmanned aerial vehicle(UAV)in real-time flight conditions.The accelerometer and... A gradient descent algorithm with adjustable parameter for attitude estimation is developed,aiming at the attitude measurement for small unmanned aerial vehicle(UAV)in real-time flight conditions.The accelerometer and magnetometer are introduced to construct an error equation with the gyros,thus the drifting characteristics of gyroscope can be compensated by solving the error equation utilized by the gradient descent algorithm.Performance of the presented algorithm is evaluated using a self-proposed micro-electro-mechanical system(MEMS)based attitude heading reference system which is mounted on a tri-axis turntable.The on-ground,turntable and flight experiments indicate that the estimation attitude has a good accuracy.Also,the presented system is compared with an open-source flight control system which runs extended Kalman filter(EKF),and the results show that the attitude control system using the gradient descent method can estimate the attitudes for UAV effectively. 展开更多
关键词 gradient descent algorithm attitude estimation QUATERNIONS small unmanned aerial vehicle(UAV)
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Efficient and High-quality Recommendations via Momentum-incorporated Parallel Stochastic Gradient Descent-Based Learning 被引量:7
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作者 Xin Luo Wen Qin +2 位作者 Ani Dong Khaled Sedraoui MengChu Zhou 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2021年第2期402-411,共10页
A recommender system(RS)relying on latent factor analysis usually adopts stochastic gradient descent(SGD)as its learning algorithm.However,owing to its serial mechanism,an SGD algorithm suffers from low efficiency and... A recommender system(RS)relying on latent factor analysis usually adopts stochastic gradient descent(SGD)as its learning algorithm.However,owing to its serial mechanism,an SGD algorithm suffers from low efficiency and scalability when handling large-scale industrial problems.Aiming at addressing this issue,this study proposes a momentum-incorporated parallel stochastic gradient descent(MPSGD)algorithm,whose main idea is two-fold:a)implementing parallelization via a novel datasplitting strategy,and b)accelerating convergence rate by integrating momentum effects into its training process.With it,an MPSGD-based latent factor(MLF)model is achieved,which is capable of performing efficient and high-quality recommendations.Experimental results on four high-dimensional and sparse matrices generated by industrial RS indicate that owing to an MPSGD algorithm,an MLF model outperforms the existing state-of-the-art ones in both computational efficiency and scalability. 展开更多
关键词 Big data industrial application industrial data latent factor analysis machine learning parallel algorithm recommender system(RS) stochastic gradient descent(SGD)
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PROJECTED GRADIENT DESCENT BASED ON SOFT THRESHOLDING IN MATRIX COMPLETION 被引量:1
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作者 Zhao Yujuan Zheng Baoyu Chen Shouning 《Journal of Electronics(China)》 2013年第6期517-524,共8页
Matrix completion is the extension of compressed sensing.In compressed sensing,we solve the underdetermined equations using sparsity prior of the unknown signals.However,in matrix completion,we solve the underdetermin... Matrix completion is the extension of compressed sensing.In compressed sensing,we solve the underdetermined equations using sparsity prior of the unknown signals.However,in matrix completion,we solve the underdetermined equations based on sparsity prior in singular values set of the unknown matrix,which also calls low-rank prior of the unknown matrix.This paper firstly introduces basic concept of matrix completion,analyses the matrix suitably used in matrix completion,and shows that such matrix should satisfy two conditions:low rank and incoherence property.Then the paper provides three reconstruction algorithms commonly used in matrix completion:singular value thresholding algorithm,singular value projection,and atomic decomposition for minimum rank approximation,puts forward their shortcoming to know the rank of original matrix.The Projected Gradient Descent based on Soft Thresholding(STPGD),proposed in this paper predicts the rank of unknown matrix using soft thresholding,and iteratives based on projected gradient descent,thus it could estimate the rank of unknown matrix exactly with low computational complexity,this is verified by numerical experiments.We also analyze the convergence and computational complexity of the STPGD algorithm,point out this algorithm is guaranteed to converge,and analyse the number of iterations needed to reach reconstruction error.Compared the computational complexity of the STPGD algorithm to other algorithms,we draw the conclusion that the STPGD algorithm not only reduces the computational complexity,but also improves the precision of the reconstruction solution. 展开更多
关键词 Matrix Completion (MC) Compressed Sensing (CS) Iterative thresholding algorithm Projected gradient descent based on Soft Thresholding (STPGD)
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Fractional Gradient Descent RBFNN for Active Fault-Tolerant Control of Plant Protection UAVs
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作者 Lianghao Hua Jianfeng Zhang +1 位作者 Dejie Li Xiaobo Xi 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第3期2129-2157,共29页
With the increasing prevalence of high-order systems in engineering applications, these systems often exhibitsignificant disturbances and can be challenging to model accurately. As a result, the active disturbance rej... With the increasing prevalence of high-order systems in engineering applications, these systems often exhibitsignificant disturbances and can be challenging to model accurately. As a result, the active disturbance rejectioncontroller (ADRC) has been widely applied in various fields. However, in controlling plant protection unmannedaerial vehicles (UAVs), which are typically large and subject to significant disturbances, load disturbances andthe possibility of multiple actuator faults during pesticide spraying pose significant challenges. To address theseissues, this paper proposes a novel fault-tolerant control method that combines a radial basis function neuralnetwork (RBFNN) with a second-order ADRC and leverages a fractional gradient descent (FGD) algorithm.We integrate the plant protection UAV model’s uncertain parameters, load disturbance parameters, and actuatorfault parameters and utilize the RBFNN for system parameter identification. The resulting ADRC exhibits loaddisturbance suppression and fault tolerance capabilities, and our proposed active fault-tolerant control law hasLyapunov stability implications. Experimental results obtained using a multi-rotor fault-tolerant test platformdemonstrate that the proposed method outperforms other control strategies regarding load disturbance suppressionand fault-tolerant performance. 展开更多
关键词 Radial basis function neural network plant protection unmanned aerial vehicle active disturbance rejection controller fractional gradient descent algorithm
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Research on three-dimensional attack area based on improved backtracking and ALPS-GP algorithms of air-to-air missile
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作者 ZHANG Haodi WANG Yuhui HE Jiale 《Journal of Systems Engineering and Electronics》 2025年第1期292-310,共19页
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
关键词 air combat three-dimensional attack area improved backtracking algorithm age-layered population structure genetic programming(ALPS-GP) gradient descent algorithm
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不同训练算法下光子神经网络鲁棒性能研究
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作者 陆鸣豪 陆云清 +3 位作者 曹雯 刘美玉 邵晓锋 王瑾 《自动化技术与应用》 2026年第1期17-21,共5页
优化了训练算法和学习率组合以提高光子神经网络(optical neural network,ONN)对器件误差的鲁棒性能,同时确保其对数字图像的高精确识别。仿真搭建两种全连接ONN架构,即GridNet和FFTNet,其中使用马赫曾德尔干涉仪(mach-zehnder interfer... 优化了训练算法和学习率组合以提高光子神经网络(optical neural network,ONN)对器件误差的鲁棒性能,同时确保其对数字图像的高精确识别。仿真搭建两种全连接ONN架构,即GridNet和FFTNet,其中使用马赫曾德尔干涉仪(mach-zehnder interferometers,MZI)作为光子器件,并对含有器件误差的ONN进行了不同算法的训练,包括随机梯度下降(stochastic gradient descent,SGD)、均方根传递(root mean square prop,RMSprop)、适应性矩估计(adaptive moment estimation,Adam)和自适应梯度下降(adaptive gradient,Adagrad)。结果表明,在不同程度的器件误差下,FFTNet型ONN比GridNet型ONN更鲁棒。具体来说,采用学习率为0.005的RMSprop和Adam算法以及学习率为0.5的Adagrad算法训练的FFTNet型ONN在数字图像识别精度和器件误差鲁棒性上表现最佳。优化训练算法和学习率的组合可以有效提高ONN的鲁棒性能。 展开更多
关键词 光子神经网络 器件误差 马赫曾德尔干涉仪 梯度下降算法 学习率
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基于GDA的置信规则库参数训练的集成学习方法 被引量:2
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作者 吴伟昆 傅仰耿 +2 位作者 苏群 吴英杰 巩晓婷 《计算机科学与探索》 CSCD 北大核心 2016年第12期1651-1661,共11页
目前对置信规则库(belief rule base,BRB)的研究主要针对单个BRB系统,然而单个BRB系统的推理性能不仅受参数取值的影响,而且当训练集分布不均衡或数据量较少时,容易导致参数训练不全面,从而使得推理结果所提供的决策信息存在局部性。通... 目前对置信规则库(belief rule base,BRB)的研究主要针对单个BRB系统,然而单个BRB系统的推理性能不仅受参数取值的影响,而且当训练集分布不均衡或数据量较少时,容易导致参数训练不全面,从而使得推理结果所提供的决策信息存在局部性。通过引入Bagging算法和Ada Boost算法,分别与BRB相结合提出了基于梯度下降法(gradient descent algorithm,GDA)的置信规则库系统的集成学习方法,并分别应用于输油管道检漏、多峰函数的置信规则库训练,将多个BRB子系统集成,提高系统的推理性能。在实验中,以收敛精度和曲线拟合效果作为衡量指标来分析集成系统的性能,并将集成系统与其他单个BRB系统进行比较,实验结果表明BRB集成学习方法合理有效。 展开更多
关键词 置信规则库(BRB) 集成学习 梯度下降法(gda) BAGGING ADABOOST
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欺骗性干扰场景下的功率带宽联合分配策略
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作者 李辉 武会斌 +2 位作者 王伟东 张恺 侯庆华 《电子科技》 2026年第2期19-27,共9页
针对欺骗性干扰导致的雷达性能下降问题,文中提出了一种功率带宽联合分配方案来提高雷达的探测精度,并借助高探测性能来提高雷达的抗干扰决策能力。以欺骗性距离的三维CRLB(Cramer-Rao Lower Bound)来代表雷达的探测精度,并将CRLB作为... 针对欺骗性干扰导致的雷达性能下降问题,文中提出了一种功率带宽联合分配方案来提高雷达的探测精度,并借助高探测性能来提高雷达的抗干扰决策能力。以欺骗性距离的三维CRLB(Cramer-Rao Lower Bound)来代表雷达的探测精度,并将CRLB作为目标函数建立优化问题。在考虑资源有限情况下,将优化问题中的功率资源总量和带宽资源总量限制在固定范围内。根据资源优化分配问题的非凸非线性特点提出了循环最小化算法和投影梯度下降算法相结合的解决方案。在不同雷达布局下进行仿真实验。仿真结果表明,相较于未优化的分配方案,资源联合优化的分配方案的CRLB数值降低了20%~30%,从而提高了雷达的探测精度,并缓解了欺骗性干扰导致的性能下降问题。 展开更多
关键词 分布式MIMO雷达 欺骗性干扰 假目标辨识 雷达资源分配 CRLB 循环最小化算法 非凸优化问题求解 投影梯度下降算法
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A Primal-Dual SGD Algorithm for Distributed Nonconvex Optimization 被引量:8
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作者 Xinlei Yi Shengjun Zhang +2 位作者 Tao Yang Tianyou Chai Karl Henrik Johansson 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2022年第5期812-833,共22页
The distributed nonconvex optimization problem of minimizing a global cost function formed by a sum of n local cost functions by using local information exchange is considered.This problem is an important component of... The distributed nonconvex optimization problem of minimizing a global cost function formed by a sum of n local cost functions by using local information exchange is considered.This problem is an important component of many machine learning techniques with data parallelism,such as deep learning and federated learning.We propose a distributed primal-dual stochastic gradient descent(SGD)algorithm,suitable for arbitrarily connected communication networks and any smooth(possibly nonconvex)cost functions.We show that the proposed algorithm achieves the linear speedup convergence rate O(1/(√nT))for general nonconvex cost functions and the linear speedup convergence rate O(1/(nT)) when the global cost function satisfies the Polyak-Lojasiewicz(P-L)condition,where T is the total number of iterations.We also show that the output of the proposed algorithm with constant parameters linearly converges to a neighborhood of a global optimum.We demonstrate through numerical experiments the efficiency of our algorithm in comparison with the baseline centralized SGD and recently proposed distributed SGD algorithms. 展开更多
关键词 Distributed nonconvex optimization linear speedup Polyak-Lojasiewicz(P-L)condition primal-dual algorithm stochastic gradient descent
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A Note on Global Convergence Result for Conjugate Gradient Methods
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作者 BAI Yan qin Department of Mathematics, College of Sciences, Shanghai University, Shanghai 200436, China 《Journal of Shanghai University(English Edition)》 CAS 2001年第1期15-19,共5页
We extend a results presented by Y.F. Hu and C.Storey (1991) [1] on the global convergence result for conjugate gradient methods with different choices for the parameter β k . In this note, the condit... We extend a results presented by Y.F. Hu and C.Storey (1991) [1] on the global convergence result for conjugate gradient methods with different choices for the parameter β k . In this note, the conditions given on β k are milder than that used by Y.F. Hu and C. Storey. 展开更多
关键词 conjugate gradient algorithm descent property global convergence restarting
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ENTROPICAL OPTIMAL TRANSPORT,SCHRODINGER'S SYSTEM AND ALGORITHMS
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作者 Liming WU 《Acta Mathematica Scientia》 SCIE CSCD 2021年第6期2183-2197,共15页
In this exposition paper we present the optimal transport problem of Monge-Ampère-Kantorovitch(MAK in short)and its approximative entropical regularization.Contrary to the MAK optimal transport problem,the soluti... In this exposition paper we present the optimal transport problem of Monge-Ampère-Kantorovitch(MAK in short)and its approximative entropical regularization.Contrary to the MAK optimal transport problem,the solution of the entropical optimal transport problem is always unique,and is characterized by the Schrödinger system.The relationship between the Schrödinger system,the associated Bernstein process and the optimal transport was developed by Léonard[32,33](and by Mikami[39]earlier via an h-process).We present Sinkhorn’s algorithm for solving the Schrödinger system and the recent results on its convergence rate.We study the gradient descent algorithm based on the dual optimal question and prove its exponential convergence,whose rate might be independent of the regularization constant.This exposition is motivated by recent applications of optimal transport to different domains such as machine learning,image processing,econometrics,astrophysics etc.. 展开更多
关键词 entropical optimal transport Schrödinger system Sinkhorn’s algorithm gradient descent
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Chimp Optimization Algorithm Based Feature Selection with Machine Learning for Medical Data Classification
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作者 Firas Abedi Hayder M.A.Ghanimi +6 位作者 Abeer D.Algarni Naglaa F.Soliman Walid El-Shafai Ali Hashim Abbas Zahraa H.Kareem Hussein Muhi Hariz Ahmed Alkhayyat 《Computer Systems Science & Engineering》 SCIE EI 2023年第12期2791-2814,共24页
Datamining plays a crucial role in extractingmeaningful knowledge fromlarge-scale data repositories,such as data warehouses and databases.Association rule mining,a fundamental process in data mining,involves discoveri... Datamining plays a crucial role in extractingmeaningful knowledge fromlarge-scale data repositories,such as data warehouses and databases.Association rule mining,a fundamental process in data mining,involves discovering correlations,patterns,and causal structures within datasets.In the healthcare domain,association rules offer valuable opportunities for building knowledge bases,enabling intelligent diagnoses,and extracting invaluable information rapidly.This paper presents a novel approach called the Machine Learning based Association Rule Mining and Classification for Healthcare Data Management System(MLARMC-HDMS).The MLARMC-HDMS technique integrates classification and association rule mining(ARM)processes.Initially,the chimp optimization algorithm-based feature selection(COAFS)technique is employed within MLARMC-HDMS to select relevant attributes.Inspired by the foraging behavior of chimpanzees,the COA algorithm mimics their search strategy for food.Subsequently,the classification process utilizes stochastic gradient descent with a multilayer perceptron(SGD-MLP)model,while the Apriori algorithm determines attribute relationships.We propose a COA-based feature selection approach for medical data classification using machine learning techniques.This approach involves selecting pertinent features from medical datasets through COA and training machine learning models using the reduced feature set.We evaluate the performance of our approach on various medical datasets employing diverse machine learning classifiers.Experimental results demonstrate that our proposed approach surpasses alternative feature selection methods,achieving higher accuracy and precision rates in medical data classification tasks.The study showcases the effectiveness and efficiency of the COA-based feature selection approach in identifying relevant features,thereby enhancing the diagnosis and treatment of various diseases.To provide further validation,we conduct detailed experiments on a benchmark medical dataset,revealing the superiority of the MLARMCHDMS model over other methods,with a maximum accuracy of 99.75%.Therefore,this research contributes to the advancement of feature selection techniques in medical data classification and highlights the potential for improving healthcare outcomes through accurate and efficient data analysis.The presented MLARMC-HDMS framework and COA-based feature selection approach offer valuable insights for researchers and practitioners working in the field of healthcare data mining and machine learning. 展开更多
关键词 Association rule mining data classification healthcare data machine learning parameter tuning data mining feature selection MLARMC-HDMS COA stochastic gradient descent Apriori algorithm
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基于BPNN-EKF-GD-RF算法的锂离子电池组荷电状态估计方法 被引量:1
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作者 来鑫 翁嘉辉 +4 位作者 杨一鹏 孙宇飞 周龙 郑岳久 韩雪冰 《机械工程学报》 北大核心 2025年第12期251-265,共15页
锂离子电池模组的荷电状态估计(State-of-charge, SOC)是影响电池性能的一个重要内部状态,是电池组进行其它状态估计的基础。然而它的估计准确性易受温度等外部因素影响,且电池间的不一致性也为电池组中各单体电池的SOC估计带来了困难... 锂离子电池模组的荷电状态估计(State-of-charge, SOC)是影响电池性能的一个重要内部状态,是电池组进行其它状态估计的基础。然而它的估计准确性易受温度等外部因素影响,且电池间的不一致性也为电池组中各单体电池的SOC估计带来了困难。提出一种将BP神经网络(Back propagation neural network, BPNN)与扩展卡尔曼滤波(Extended Kalman filter, EKF)算法相结合的电池组SOC估计方法。该方法首先基于先验SOC利用BPNN估计不同温度下“领导者”电池的端电压,将其与实测端电压对比后采用EKF算法完成SOC后验估计,同时基于电压差采用梯度下降(Gradient descent, GD)算法更新BPNN的输出层权重使算法更快收敛。在此基础上,设计修正策略利用随机森林(Random forest, RF)算法对“跟随者”电池的SOC进行调整估计。试验结果表明,所提的BPNN-EKF-GD-RF算法能实现电池组在不同温度下SOC的准确估计,常温下SOC估计误差保持在2.5%以内,在温度变化下电池组中单体电池SOC估计最大误差不超过3.2%,为复杂环境下锂离子电池组的SOC估计提供了一种高精度低复杂度方案。 展开更多
关键词 SOC估计 BP神经网络 扩展卡尔曼滤波 梯度下降算法 随机森林 锂离子电池组
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基于神经网络的船舶辐射噪声预报方法 被引量:2
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作者 黄欣 徐荣武 李瑞彪 《船舶力学》 北大核心 2025年第3期486-496,共11页
针对船舶机械设备众多、结构复杂、振动传递路径相互耦合的现状,本文提出基于误差反向传播(Back Propagation, BP)神经网络的船舶水下辐射噪声预报方法。分别构建基于梯度下降算法和贝叶斯正则化算法的BP神经网络,以振动数据为输入量、... 针对船舶机械设备众多、结构复杂、振动传递路径相互耦合的现状,本文提出基于误差反向传播(Back Propagation, BP)神经网络的船舶水下辐射噪声预报方法。分别构建基于梯度下降算法和贝叶斯正则化算法的BP神经网络,以振动数据为输入量、船体辐射噪声为输出量,将均方根误差(e RMSE)和平均绝对误差(e MAE)作为模型预测精度评价指标。结果表明,贝叶斯正则化BP神经网络的泛化性和鲁棒性优于梯度下降算法的BP神经网络,误差达到3 dB以内,在船舶辐射噪声预报领域具有较好的适用性。 展开更多
关键词 辐射噪声预报 BP神经网络 梯度下降算法 贝叶斯正则化算法
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具有多型避障方式的智能车辆路径规划 被引量:2
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作者 胡子牛 陈鑫鹏 +3 位作者 杨泽宇 余子云 秦洪懋 高铭 《汽车工程》 北大核心 2025年第3期402-411,共10页
非结构化场景往往存在多种尺寸各异的障碍物,路径规划过程只考虑绕行的避障方式会导致车辆通行效率降低。针对该问题,本文在传统混合A^(*)算法中融合分层碰撞检测策略,提出了一种具有多型避障方式的智能车辆路径规划方法。首先,以车辆... 非结构化场景往往存在多种尺寸各异的障碍物,路径规划过程只考虑绕行的避障方式会导致车辆通行效率降低。针对该问题,本文在传统混合A^(*)算法中融合分层碰撞检测策略,提出了一种具有多型避障方式的智能车辆路径规划方法。首先,以车辆底盘高度为基准构造上下双层栅格地图,并利用车身轮廓和四轮轮廓设计分层碰撞检测策略;然后,通过合理设计的启发函数与代价函数计算方式,使得混合A^(*)算法能够在多障碍物场景中高效搜索路径;最后,利用梯度下降法对路径进行平滑优化。仿真与实车试验结果表明,所提出算法可有效提高路径搜索效率并改善路径平滑性,且规划路径兼顾了跨障与绕障方式,使得车辆在多障碍物场景下具备更良好的通过性。 展开更多
关键词 路径规划 混合A*算法 分层碰撞检测策略 梯度下降法
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考虑岩层倾角-围压组合效应的岩石强度行为初探
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作者 罗斌玉 苏辕 +4 位作者 刘晓云 黄腾达 肖枫亦 刘兰心 李鹏程 《岩土力学》 北大核心 2025年第3期775-788,共14页
研究岩石强度行为的岩层倾角-围压组合效应是揭示充填体约束缓倾斜矿柱强度行为的基础。采用数值模拟代替围压下的岩石倾斜加载试验,研究倾角-围压下岩石剪切破坏规律和强度特征。以红砂岩为研究对象,开展红砂岩单轴和剪切试验,获得红... 研究岩石强度行为的岩层倾角-围压组合效应是揭示充填体约束缓倾斜矿柱强度行为的基础。采用数值模拟代替围压下的岩石倾斜加载试验,研究倾角-围压下岩石剪切破坏规律和强度特征。以红砂岩为研究对象,开展红砂岩单轴和剪切试验,获得红砂岩的基本力学参数。以校核过的红砂岩基本力学参数为基础,开展7种倾角6种围压组合的岩石倾斜加载数值模拟,获取倾角-围压下岩石剪切破坏规律和强度特征。结果显示,随着倾角的增大,剪切带与水平面的倾角越大,且围压越大,剪切带变厚;增大围压能有效降低倾角对岩石强度的影响。然后利用非常规应力圆表征极限状态下岩石应力状态的围压-倾角效应,随着倾角的增大非常规应力圆圆心偏离正应力轴的程度越大,揭示了应力路径的变化规律。基于Mohr-Coulomb强度理论,采用梯度下降算法,将7种倾角6个围压下应力圆上表示极限应力状态的“点”联系起来,求得7种倾角对应的7组强度包络线方程。采用多项式逼近方法,引入倾角维度,将7组“强度包络线”向“强度曲面”拓展,实现从“点”到“线”扩展到“面”的转变,构建包含倾角因素的岩石强度模型。研究结果对揭示矿柱等岩体工程强度的倾角-围压耦合效应具有重要科学意义。 展开更多
关键词 强度行为 倾角效应 围压效应 MOHR-COULOMB准则 梯度下降算法
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基于梯度下降与直流偏置补偿的多模分布式光纤测温系统性能优化
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作者 张晓峰 梁笑 +5 位作者 马旭斌 齐军 周应庆 任杰 邓伟锋 韩静昳 《光子学报》 北大核心 2025年第12期113-121,共9页
针对多模光纤传感中信号衰减、色散效应及雪崩光电二极管直流偏置耦合导致的温度漂移问题,提出一种基于梯度下降算法的多维度补偿优化框架。通过融合分段色散补偿、累加平均去噪与动态直流偏置修正,系统性提升斯托克斯/反斯托克斯双路... 针对多模光纤传感中信号衰减、色散效应及雪崩光电二极管直流偏置耦合导致的温度漂移问题,提出一种基于梯度下降算法的多维度补偿优化框架。通过融合分段色散补偿、累加平均去噪与动态直流偏置修正,系统性提升斯托克斯/反斯托克斯双路信号的对准精度与信噪比。实验结果表明,在4 km多模光纤传感系统中,该算法将测温精度优化至0.66℃,且熔接点温度波动抑制至2℃以内,系统空间分辨率为1.5 m。本研究为长距离、复杂环境下的分布式温度监测提供了高精度、低成本的解决方案,具有显著的工程应用潜力。 展开更多
关键词 分布式光纤测温系统 拉曼散射 梯度下降算法 色散补偿 直流偏置优化
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LLM-105的ReaxFF参数优化与分子动力学模拟 被引量:1
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作者 宋亮 张泳 +5 位作者 叶婧 陈博聪 侯方超 苏浩龙 蒋俊 周素芹 《火炸药学报》 北大核心 2025年第2期138-149,I0006,共13页
针对ReaxFF初始力场描述2,6-二氨基-3,5-二硝基-1-氧化物(LLM-105)的不足,采用了一种基于梯度下降算法JAX-ReaxFF框架策略,对ReaxFF反应力场进行了重新参数化,特别关注不同键和键角的势能面解离变化;在模拟不同温度和分解速率的反应过程... 针对ReaxFF初始力场描述2,6-二氨基-3,5-二硝基-1-氧化物(LLM-105)的不足,采用了一种基于梯度下降算法JAX-ReaxFF框架策略,对ReaxFF反应力场进行了重新参数化,特别关注不同键和键角的势能面解离变化;在模拟不同温度和分解速率的反应过程中,深入分析了LLM-105的反应机制。结果表明,当温度为1500 K时,分子反应主要聚焦于聚合和脱氢反应;随着温度的逐渐升高,LLM-105的反应模式呈现出了新的变化,当温度不小于2000 K时,除了原有的聚合和脱氢反应外,还观察到了C-NO_(2)键和C-NH_(2)键的断裂现象;值得注意的是,C-NO_(2)键的断裂成为触发这一系列反应的关键因素;随着分子中的C-NO_(2)和C-NH_(2)键开始发生均裂反应,促进了中间产物HON_(2)、NO_(2)和NH_(3)的形成,并经历一系列复杂的相互反应,最终生成了N_(2)、H_(2)O和CO_(2)等稳定产物,表明该力场能够有效模拟在不同温度和加热速率下的化学反应变化。 展开更多
关键词 量子化学 LLM-105 梯度下降算法 分解机制 分子动力学模拟 ReaxFF力场
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基于频谱效率公平性的XL-MIMO系统预编码优化
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作者 李志立 傅友华 宋云超 《数据采集与处理》 北大核心 2025年第6期1434-1444,共11页
本文研究了在近场信道模型下基于频谱效率公平性的超大规模多输入多输出(Extremely large‑scale multiple‑input‑multiple‑output,XL‑MIMO)下行系统的预编码优化问题。考虑在该近场信道模型,即小区内同时存在视距(Line‑of‑sight,LOS)和... 本文研究了在近场信道模型下基于频谱效率公平性的超大规模多输入多输出(Extremely large‑scale multiple‑input‑multiple‑output,XL‑MIMO)下行系统的预编码优化问题。考虑在该近场信道模型,即小区内同时存在视距(Line‑of‑sight,LOS)和非视距(Non LOS,NLOS)的非平稳混合信道,其中LOS信道采用球面波模型,而NLOS信道则采用瑞利模型。以频谱效率的几何平均值作为优化目标,从而确保用户间的公平性并优化系统整体的频谱效率。为了处理复杂的优化目标函数,首先对其采用泰勒展开的一阶近似作为新的目标函数。接着,使用拉格朗日对偶变换和二次变换将原始优化问题转化为更容易求解的等价问题。最后,为了降低计算复杂度,采用了快速迭代收缩阈值算法与投影梯度下降算法结合的投影快速迭代收缩阈值算法(Projection fast iterative shrinkage threshold algorithm,PFISTA)来解决等效优化问题。仿真结果显示,以几何平均值作为目标函数能够降低用户频谱效率之间的差异,实现用户频谱效率的均衡提升。此外,PFISTA在获得与现有方法相当性能的同时,具有较低的计算复杂度。 展开更多
关键词 非平稳 球面波 快速迭代收缩阈值算法 投影梯度下降 拉格朗日对偶变换
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基于SPGD算法的GTI腔短脉冲时域相干堆积闭环控制研究
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作者 刘必达 黄智蒙 +2 位作者 张帆 周丹丹 彭志涛 《光学与光电技术》 2025年第5期118-123,共6页
为了在短脉冲时域相干堆积系统中实现光腔相位高效闭环控制,利用一种基于扰动幅度e指数匀滑的随机并行梯度下降(Stochastic Parallel Gradient Descent Algorithm,SPGD)算法,对Gires-Tournois干涉仪(Gires-Tournois Interferometer,GTI... 为了在短脉冲时域相干堆积系统中实现光腔相位高效闭环控制,利用一种基于扰动幅度e指数匀滑的随机并行梯度下降(Stochastic Parallel Gradient Descent Algorithm,SPGD)算法,对Gires-Tournois干涉仪(Gires-Tournois Interferometer,GTI)堆积腔的相位进行闭环控制,实验研究了增益系数和扰动幅度两个主要算法参量对相干堆积效果的影响,结果表明,两个参数对堆积效果的影响规律相似,设置过小易陷入局部极值,过大会使得堆积波形发生振荡,无法稳定在最大值。通过优化控制参数选取,获得了稳定的相干堆积,合成后主、副脉冲峰值比达到6.43∶1。该结果对短脉冲时域相干堆积中的光腔相位控制具有重要的参考价值。 展开更多
关键词 光纤激光 短脉冲 脉冲相干堆积 光腔相位控制 随机并行梯度下降算法
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