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On the 4D Variational Data Assimilation with Constraint Conditions 被引量:1
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作者 朱克云 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2001年第6期1131-1145,共15页
An investigation is carried out on the problem involved in 4D variational data assimilation (VDA) with constraint conditions based on a finite-element shallow-water equation model. In the investigation, the adjoint te... An investigation is carried out on the problem involved in 4D variational data assimilation (VDA) with constraint conditions based on a finite-element shallow-water equation model. In the investigation, the adjoint technology, penalty method and augmented Lagrangian method are used in constraint optimization field to minimize the defined constraint objective functions. The results of the numerical experiments show that the optimal solutions are obtained if the functions reach the minima. VDA with constraint conditions controlling the growth of gravity oscillations is efficient to eliminate perturbation and produces optimal initial field. It seems that this method can also be applied to the problem in numerical weather prediction. Key words Variational data assimilation - Constraint conditions - Penalty methods - finite-element model This research is supported by National Natural Science Foundation of China (Grant No. 49575269) and by National Key Basic Research on the Formation Mechanism and Prediction Theory of Severe Synoptic Disasters (Grant No. G1998040910). 展开更多
关键词 variational data assimilation Constraint conditions Penalty methods finite-element model
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The Convergence Rate of Fréchet Distribution under the Second-Order Regular Variation Condition
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作者 Xilai Dai 《Journal of Applied Mathematics and Physics》 2024年第5期1597-1605,共9页
In this article we consider the asymptotic behavior of extreme distribution with the extreme value index γ>0 . The rates of uniform convergence for Fréchet distribution are constructed under the second-order ... In this article we consider the asymptotic behavior of extreme distribution with the extreme value index γ>0 . The rates of uniform convergence for Fréchet distribution are constructed under the second-order regular variation condition. 展开更多
关键词 Convergence Rate Second-Order Regular variation condition Fréchet Distribution Extreme Value Index
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Necessary Optimality Conditions for Multi-Objective Semi-Infinite Variational Problem 被引量:1
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作者 Bharti Sharma Promila Kumar 《American Journal of Operations Research》 2016年第1期36-43,共8页
In this paper, necessary optimality conditions for a class of Semi-infinite Variational Problems are established which are further generalized to a class of Multi-objective Semi-Infinite Variational Problems. These co... In this paper, necessary optimality conditions for a class of Semi-infinite Variational Problems are established which are further generalized to a class of Multi-objective Semi-Infinite Variational Problems. These conditions are responsible for the development of duality theory which is an extremely important feature for any class of problems, but the literature available so far lacks these necessary optimality conditions for the stated problem. A lemma is also proved to find the topological dual of  as it is required to prove the desired result. 展开更多
关键词 SEMI-INFINITE variational Problem Efficient Solution Necessary Optimality conditions
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THE ELLIPTIC VARIATIONAL INEQUALITIES WITH DOUBLE DEGENERATE AND GENERAL GROWTH CONDITIONS
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作者 LI SHENGHONG(Department of Mathematfics,Eat China Normal University,Shanghai 200062.) 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 1996年第3期323-334,共12页
A class of quasilinear elliptic variational inequalities with double degenerate is discussed in this paper. We extend the Keldys-Fichera boundary value problem and the first boundary problem of degenerate elliptic equ... A class of quasilinear elliptic variational inequalities with double degenerate is discussed in this paper. We extend the Keldys-Fichera boundary value problem and the first boundary problem of degenerate elliptic equation to the variationalinequalities. We establish the existence and uniqueness of the weak solution of ocrresspending problem under nonstandard growth conditions. 展开更多
关键词 Elliptic variational inequalities double degenerate Keldys-Fichera boundary nonstandard growth conditions.
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Study of current distribution generation in PEMFC based on conditional variational auto-encoder
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作者 Chengyin Shi Cong Yin +2 位作者 Weilong Luo Hailong Liu Hao Tang 《Energy and AI》 2025年第3期578-591,共14页
The Proton Exchange Membrane Fuel Cell(PEMFC)converts the chemical energy of hydrogen fuel directly into electrical energy with broad application prospects.Understanding how current density is distributed in the PEMFC... The Proton Exchange Membrane Fuel Cell(PEMFC)converts the chemical energy of hydrogen fuel directly into electrical energy with broad application prospects.Understanding how current density is distributed in the PEMFC systems is crucial as it is a key factor influencing system performance.However,direct modeling for current distribution may encounter the challenge of dimensional catastrophe owing to the high dimensionality of the data.This paper uses a high-resolution segmented measurement device with 396 points to conduct experimental tests on the current distribution of a PEMFC with reactive area of 406 cm^(2) during a stepwise increase in load current.The current distribution is modeled based on the test results to learn the mapping relationship between the experimental parameters and the current distribution.The proposed model utilizes a Conditional Variational Auto-Encoder(CVAE)to generate current distributions.The MSE(Mean-Square Error)of the trained CVAE model reaches 9.2×10^(-5),and the comparison results show that the 222.9A current distribution error has the largest MSE of 6.36×10^(-4) and a KL Divergence(Kullback-Leibler Divergence)of 9.55×10^(-4),both of which are at a low level.This model enables the direct determination of the current distribution based on the experimental parameters,thereby establishing a technical foundation for investigating the impact of experimental conditions on fuel cells.This model is also of great significance for research on fuel cell system control strategies and fault diagnosis. 展开更多
关键词 Proton exchange membrane fuel cell Segmented measurement device Current distribution conditional variational auto-encoder
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Wavelet Transform-Based Bayesian Inference Learning with Conditional Variational Autoencoder for Mitigating Injection Attack in 6G Edge Network
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作者 Binu Sudhakaran Pillai Raghavendra Kulkarni +1 位作者 Venkata Satya Suresh kumar Kondeti Surendran Rajendran 《Computer Modeling in Engineering & Sciences》 2025年第10期1141-1166,共26页
Future 6G communications will open up opportunities for innovative applications,including Cyber-Physical Systems,edge computing,supporting Industry 5.0,and digital agriculture.While automation is creating efficiencies... Future 6G communications will open up opportunities for innovative applications,including Cyber-Physical Systems,edge computing,supporting Industry 5.0,and digital agriculture.While automation is creating efficiencies,it can also create new cyber threats,such as vulnerabilities in trust and malicious node injection.Denialof-Service(DoS)attacks can stop many forms of operations by overwhelming networks and systems with data noise.Current anomaly detection methods require extensive software changes and only detect static threats.Data collection is important for being accurate,but it is often a slow,tedious,and sometimes inefficient process.This paper proposes a new wavelet transformassisted Bayesian deep learning based probabilistic(WT-BDLP)approach tomitigate malicious data injection attacks in 6G edge networks.The proposed approach combines outlier detection based on a Bayesian learning conditional variational autoencoder(Bay-LCVariAE)and traffic pattern analysis based on continuous wavelet transform(CWT).The Bay-LCVariAE framework allows for probabilistic modelling of generative features to facilitate capturing how features of interest change over time,spatially,and for recognition of anomalies.Similarly,CWT allows emphasizing the multi-resolution spectral analysis and permits temporally relevant frequency pattern recognition.Experimental testing showed that the flexibility of the Bayesian probabilistic framework offers a vast improvement in anomaly detection accuracy over existing methods,with a maximum accuracy of 98.21%recognizing anomalies. 展开更多
关键词 Bayesian inference learning automaton convolutional wavelet transform conditional variational autoencoder malicious data injection attack edge environment 6G communication
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Variational Calculus With Conformable Fractional Derivatives 被引量:4
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作者 Matheus J.Lazo Delfim F.M.Torres 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2017年第2期340-352,共13页
Invariant conditions for conformable fractional problems of the calculus of variations under the presence of external forces in the dynamics are studied. Depending on the type of transformations considered, different ... Invariant conditions for conformable fractional problems of the calculus of variations under the presence of external forces in the dynamics are studied. Depending on the type of transformations considered, different necessary conditions of invariance are obtained. As particular cases, we prove fractional versions of Noether's symmetry theorem. Invariant conditions for fractional optimal control problems, using the Hamiltonian formalism, are also investigated. As an example of potential application in Physics, we show that with conformable derivatives it is possible to formulate an Action Principle for particles under frictional forces that is far simpler than the one obtained with classical fractional derivatives. 展开更多
关键词 Conformable fractional derivative fractional calculus of variations fractional optimal control invariant variational conditions Noether’s theorem
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An inverse design method for supercritical airfoil based on conditional generative models 被引量:11
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作者 Jing WANG Runze LI +4 位作者 Cheng HE Haixin CHEN Ran CHENG Chen ZHAI Miao ZHANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第3期62-74,共13页
Inverse design has long been an efficient and powerful design tool in the aircraft industry.In this paper,a novel inverse design method for supercritical airfoils is proposed based on generative models in deep learnin... Inverse design has long been an efficient and powerful design tool in the aircraft industry.In this paper,a novel inverse design method for supercritical airfoils is proposed based on generative models in deep learning.A Conditional Variational Auto Encoder(CVAE)and an integrated generative network CVAE-GAN that combines the CVAE with the Wasserstein Generative Adversarial Networks(WGAN),are conducted as generative models.They are used to generate target wall Mach distributions for the inverse design that matches specified features,such as locations of suction peak,shock and aft loading.Qualitative and quantitative results show that both adopted generative models can generate diverse and realistic wall Mach number distributions satisfying the given features.The CVAE-GAN model outperforms the CVAE model and achieves better reconstruction accuracies for all the samples in the dataset.Furthermore,a deep neural network for nonlinear mapping is adopted to obtain the airfoil shape corresponding to the target wall Mach number distribution.The performances of the designed deep neural network are fully demonstrated and a smoothness measurement is proposed to quantify small oscillations in the airfoil surface,proving the authenticity and accuracy of the generated airfoil shapes. 展开更多
关键词 conditional variational AutoEncoder(CVAE) Deep learning Generative Adversarial Networks(GAN) Generative models Inverse design Supercritical airfoil
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Stable Perturbed Algorithms for a New Class of Generalized Nonlinear Implicit Quasi Variational Inclusions in Banach Spaces 被引量:2
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作者 Salahuddin Salahuddin Mohammad Kalimuddin Ahmad 《Advances in Pure Mathematics》 2012年第3期139-148,共10页
In this work, a new class of variational inclusion involving T-accretive operators in Banach spaces is introduced and studied. New iterative algorithms for stability for their class of variational inclusions and its c... In this work, a new class of variational inclusion involving T-accretive operators in Banach spaces is introduced and studied. New iterative algorithms for stability for their class of variational inclusions and its convergence results are established. 展开更多
关键词 T-Accretive Operators variational INCLUSIONS Iterative Algorithms Stability conditions Convergence Strong Accretivity BANACH Spaces
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A New Variational Formulation for a Kind of Reaction-diffusion Problem in Broken Sobolev Space 被引量:1
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作者 GE Zhi-hao CAO Ji-wei 《Chinese Quarterly Journal of Mathematics》 2017年第2期134-141,共8页
In this paper, a new variational formulation for a reaction-diffusion problem in broken Sobolev space is proposed. And the new formulation in the broken Sobolev space will be proved that it is well-posed and equivalen... In this paper, a new variational formulation for a reaction-diffusion problem in broken Sobolev space is proposed. And the new formulation in the broken Sobolev space will be proved that it is well-posed and equivalent to the standard Galerkin variational formulation. The method will be helpful to easily solve the original partial differential equation numerically. And the method is novel and interesting, which can be used to deal with some complicated problem, such as the low regularity problem, the differential-integral problem and so on. 展开更多
关键词 broken Sobolev space variational formulation discontinuous Galerkin method inf-sup condition
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Variational Approach for the Adapted Solution of Backw ard Stochastic Differential Equations with Locally Lipschitz Diffusion Coefficients 被引量:1
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作者 谢臻赟 刘奕 《Journal of Donghua University(English Edition)》 EI CAS 2012年第4期341-350,共10页
One existence integral condition was obtained for the adapted solution of the general backward stochastic differential equations(BSDEs). Then by solving the integral constraint condition, and using a limit procedure, ... One existence integral condition was obtained for the adapted solution of the general backward stochastic differential equations(BSDEs). Then by solving the integral constraint condition, and using a limit procedure, a new approach method is proposed and the existence of the solution was proved for the BSDEs if the diffusion coefficients satisfy the locally Lipschitz condition. In the special case the solution was a Brownian bridge. The uniqueness is also considered in the meaning of "F0-integrable equivalent class" . The new approach method would give us an efficient way to control the main object instead of the "noise". 展开更多
关键词 backward stochastic differential equation (BSDE) variational approach locally Lipschitz condition EXISTENCE Fointegrable equivalent class UNIQUENESS Brownian bridge
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Optimality conditions for a class of variational inequalities with cone constraints
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作者 Wen DONG Junrong ZHANG +1 位作者 Yiyun WANG La HUANG 《Frontiers of Mathematics in China》 2025年第1期39-53,共15页
In this paper,through the use of image space analysis,optimality conditions for a class of variational inequalities with cone constraints are proposed.By virtue of the nonlinear scalarization function,known as the Ger... In this paper,through the use of image space analysis,optimality conditions for a class of variational inequalities with cone constraints are proposed.By virtue of the nonlinear scalarization function,known as the Gerstewitz function,three nonlinear weak separation functions,two nonlinear regular weak separation functions and a nonlinear strong separation function are introduced.According to nonlinearseparation functions,some optimality conditions of the weak and strong alternative for variational inequalities with cone constraints are derived. 展开更多
关键词 variational inequalities with constraints image space analysis nonlinear separation function optimality condition
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Variation Trends of Dust Storms in Relation to Meteorological Conditions and Anthropogenic Impacts in the Northeast Edge of the Taklimakan Desert, China 被引量:1
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作者 Aishajiang Aili Nguyen Thi Kim Oanh Jilili Abuduwaili 《Open Journal of Air Pollution》 2016年第4期127-143,共17页
To reveal the multivariate relationships between man-made and meteorological factors on dust storm frequency, the LUCC data, NDVI remote sensing data and meteorological data for the period of 1983-2013 were combined w... To reveal the multivariate relationships between man-made and meteorological factors on dust storm frequency, the LUCC data, NDVI remote sensing data and meteorological data for the period of 1983-2013 were combined with dust storm frequency data, and the possible impacts of meteorological and anthropogenic factors on dust storm frequency were analyzed by using regression analysis and PCA (Principal Component Analysis). Results show that the inter-annual dust storm frequency increased gradually. In particular, an increasing trend in recent years, after 2009, is conspicuous. The monthly frequency of dust storms shows higher values between the months of February and May, with the highest mean number of events occurring in April, which accounts for 29% of the annual dust storm frequency. The annual dust storm frequency is positively correlated with wind speed and negatively correlated with precipitation;the monthly dust storm frequency is positively correlated with wind speed, but no significant correlation can be found with precipitation. The relationship between temperature and dust storms is not simply linear, however, a certain correlation with an unremarkable statistical significance can be found between them. Human activities also affect the dynamics of dust storms indirectly via changing vegetation coverage and direct dust emissions. The multivariate analysis further confirmed the association between dust storm frequency and meteorological factors and NDVI. The high loadings of dust storm frequency, wind speed, precipitation and NDVI on a PC indicate that the increased precipitation and NDVI will decrease dust storm frequency, and increased wind speed will increase dust storm frequency. 展开更多
关键词 Dust storm variation Trends Meteorological conditions Anthropogenic Impact
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Solving the subset sum problem by the quantum Ising model with variational quantum optimization based on conditional values at risk 被引量:1
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作者 Qilin Zheng Miaomiao Yu +3 位作者 Pingyu Zhu Yan Wang Weihong Luo Ping Xu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2024年第8期43-55,共13页
The subset sum problem is a combinatorial optimization problem,and its complexity belongs to the nondeterministic polynomial time complete(NP-Complete)class.This problem is widely used in encryption,planning or schedu... The subset sum problem is a combinatorial optimization problem,and its complexity belongs to the nondeterministic polynomial time complete(NP-Complete)class.This problem is widely used in encryption,planning or scheduling,and integer partitions.An accurate search algorithm with polynomial time complexity has not been found,which makes it challenging to be solved on classical computers.To effectively solve this problem,we translate it into the quantum Ising model and solve it with a variational quantum optimization method based on conditional values at risk.The proposed model needs only n qubits to encode 2ndimensional search space,which can effectively save the encoding quantum resources.The model inherits the advantages of variational quantum algorithms and can obtain good performance at shallow circuit depths while being robust to noise,and it is convenient to be deployed in the Noisy Intermediate Scale Quantum era.We investigate the effects of the scalability,the variational ansatz type,the variational depth,and noise on the model.Moreover,we also discuss the performance of the model under different conditional values at risk.Through computer simulation,the scale can reach more than nine qubits.By selecting the noise type,we construct simulators with different QVs and study the performance of the model with them.In addition,we deploy the model on a superconducting quantum computer of the Origin Quantum Technology Company and successfully solve the subset sum problem.This model provides a new perspective for solving the subset sum problem. 展开更多
关键词 subset sum problem quantum Ising model conditional values at risk variational quantum optimization
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New smooth gap function for box constrained variational inequalities
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作者 张丽丽 李兴斯 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2013年第1期15-26,共12页
A new smooth gap function for the box constrained variational inequality problem (VIP) is proposed based on an integral global optimality condition. The smooth gap function is simple and has some good differentiable... A new smooth gap function for the box constrained variational inequality problem (VIP) is proposed based on an integral global optimality condition. The smooth gap function is simple and has some good differentiable properties. The box constrained VIP can be reformulated as a differentiable optimization problem by the proposed smooth gap function. The conditions, under which any stationary point of the optimization problem is the solution to the box constrained VIP, are discussed. A simple frictional contact problem is analyzed to show the applications of the smooth gap function. Finally, the numerical experiments confirm the good theoretical properties of the method. 展开更多
关键词 box constrained variational inequality problem (VIP) smooth gap function integral global optimality condition
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MERIT FUNCTION AND GLOBAL ALGORITHMFOR BOX CONSTRAINED VARIATIONALINEQUALITIES
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作者 张立平 高自友 赖炎连 《Acta Mathematica Scientia》 SCIE CSCD 2002年第1期63-71,共9页
The authors consider optimization methods for box constrained variational inequalities. First, the authors study the KKT-conditions problem based on the original problem. A merit function for the KKT-conditions proble... The authors consider optimization methods for box constrained variational inequalities. First, the authors study the KKT-conditions problem based on the original problem. A merit function for the KKT-conditions problem is proposed, and some desirable properties of the merit function are obtained. Through the merit function, the original problem is reformulated as minimization with simple constraints. Then, the authors show that any stationary point of the optimization problem is a solution of the original problem. Finally, a descent algorithm is presented for the optimization problem, and global convergence is shown. 展开更多
关键词 box constrained variational inequalities the KKT-conditions problem global convergence algorithm
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QUASI-VARIATIONAL PRINCIPLE FOR THE VORTEX-POTENTIAL FUNCTION OF ROTATIONAL FLOW IN THREE-DIMENSION PIPE
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作者 沈远胜 刘高联 刘永杰 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2004年第1期10-15,共6页
The variational analysis of the Pseudo-potential function-vortex-potential function model, a new mathematical model, was developed and by which the flow field with transonic speed and curl was decided, and different s... The variational analysis of the Pseudo-potential function-vortex-potential function model, a new mathematical model, was developed and by which the flow field with transonic speed and curl was decided, and different sorts of the variational principle for vortex potential function were established by transforming the original equation for vortex-function, the boundary conditions for vortex-potential function was raised. 展开更多
关键词 pseudo-potential function vortex-potential function CURL quasi-variational principle boundary condition
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On Coupled Dirac Systems Under Chirality Boundary Condition
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作者 YANG Xu LI Xin 《应用数学》 北大核心 2024年第1期180-191,共12页
In this article we study the existence of solutions for the Dirac systems with the chirality boundary condition.Using an analytic framework of proper products of fractional Sobolev spaces,the solutions existence resul... In this article we study the existence of solutions for the Dirac systems with the chirality boundary condition.Using an analytic framework of proper products of fractional Sobolev spaces,the solutions existence results of the coupled Dirac systems are obtained for nonlinearity with superquadratic growth rates.The results obtained by GONG and LU(2017)are extended to the case of chiral boundary condition. 展开更多
关键词 Dirac system Boundary condition variational method
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基于改进GAN的人机交互手势行为识别方法
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作者 张富强 白筠妍 穆慧 《郑州大学学报(工学版)》 北大核心 2025年第2期43-50,共8页
为改善现有手势识别算法需要大量训练数据的现状,针对识别准确率不高、识别过程复杂等问题,基于生成式对抗网络(GAN)和变分自编码器,引入标签信息,提出一种基于改进GAN模型的人机交互手势行为识别方法。首先,在编码器和解码器中分别添... 为改善现有手势识别算法需要大量训练数据的现状,针对识别准确率不高、识别过程复杂等问题,基于生成式对抗网络(GAN)和变分自编码器,引入标签信息,提出一种基于改进GAN模型的人机交互手势行为识别方法。首先,在编码器和解码器中分别添加改进InceptionV2和InceptionV2-trans结构增强模型的特征还原能力;其次,在各组成网络中进行条件批量归一化(CBN)处理改善过拟合,以Mish激活函数代替ReLU函数提升网络性能;最后,通过实验证明该方法能够以较少的样本获得100%的分类准确率,且收敛时间短,验证了该方法的可靠性。 展开更多
关键词 人机交互 生成对抗网络 变分自编码器 手势识别 条件批量归一化
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基于改进通道注意力优化变分自编码器的居民空调负荷辨识
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作者 王凌云 唐涛 +2 位作者 鲍刚 阮胜冬 张涛 《仪器仪表学报》 北大核心 2025年第5期251-263,共13页
居民空调负荷的准确辨识是挖掘其调控潜力和实现需求响应的关键。针对目前居民空调功率求解方法的精度不足和计算复杂问题,故提出一种基于变分自编码器(VAE)和改进高效通道注意力机制(ECA)的居民空调负荷非侵入式辨识神经网络模型。改进... 居民空调负荷的准确辨识是挖掘其调控潜力和实现需求响应的关键。针对目前居民空调功率求解方法的精度不足和计算复杂问题,故提出一种基于变分自编码器(VAE)和改进高效通道注意力机制(ECA)的居民空调负荷非侵入式辨识神经网络模型。改进ECA采用结合全局平均池化与全局最大池化的双池化策略,既捕获整体统计信息又突出局部显著响应。借助压缩-重构机制,在降维后利用快速动态卷积核自适应捕捉局部通道交互信息,有效聚焦关键信息,为通道赋予合理权重;将改进ECA集成在VAE解码器中,增强模型对空调负荷的特征重构能力;模型进一步引入多任务学习框架,联合优化功率分解与状态识别任务,实现任务间信息共享和互补,从而提高整体辨识精度。同时,利用输出模块和后处理状态阈值约束,有效抑制非空调负荷的干扰。最后,在真实居民用电数据集上进行实验验证。实验结果表明,相较于两个对比模型,模型在3个地区所有居民功率分解的平均绝对误差(MAE)均值分别提升59.71%和9.22%,空调状态识别F1值达84.58%。消融实验表明,改进ECA使其中两个地区功率分解MAE分别降低56.23%和12.47%,多任务学习框架进一步推动辨识精度提升3.17%和5.90%。所提出的少量侵入式测量方案以30%用户侵入式量测数据训练,在保证模型准确性的同时,减少对用户数据的依赖,具有较强的应用潜力。 展开更多
关键词 居民空调负荷 变分自编码器 非侵入式负荷监测 通道注意力 多任务学习
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