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利用点电流源和Tikhonov正则化的潜艇稳恒电场反演方法
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作者 张建春 刘春阳 赵玉龙 《国防科技大学学报》 EI CAS CSCD 北大核心 2024年第4期212-221,共10页
为了评估潜艇水下腐蚀相关稳恒电场分布特性,从潜艇水下腐蚀相关稳恒电场产生机理出发,基于等效点电流源建立潜艇水下腐蚀相关稳恒电场正演模型,并利用Tikhonov正则化根据已知电场数据求解等效点电流源电流强度,对潜艇周围海水空间的腐... 为了评估潜艇水下腐蚀相关稳恒电场分布特性,从潜艇水下腐蚀相关稳恒电场产生机理出发,基于等效点电流源建立潜艇水下腐蚀相关稳恒电场正演模型,并利用Tikhonov正则化根据已知电场数据求解等效点电流源电流强度,对潜艇周围海水空间的腐蚀相关稳恒电场进行推算。将某型潜艇的COMSOL软件仿真结果作为模拟试验数据,对所提方法有效性进行验证。结果表明:由水深38 m电场值向水深42.5 m和水深33.5 m进行反演时,相对均方根误差、最大值相对误差、峰峰值相对误差均不超过0.06;由较近平面向较远平面进行反演时,即使推算深度达到45 m,相对均方根误差仍然在0.21以内;噪声标准差为实际电场最大值的0.1倍时,反演误差仍然小于0.1。该算法抗噪声能力强,精度较高,能较好地用于工程实践。 展开更多
关键词 潜艇电场 反演 点电流源 tikhonov正则化
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Tikhonov正则化方法在航空γ测量数据处理中的应用
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作者 李华锋 盛伟 +4 位作者 韩斌 王雪梅 王志慧 刘文彪 李国辉 《现代应用物理》 2024年第1期59-65,共7页
在航空γ测量中,当地形平坦且飞行高度变化不大时,采用传统的高度修正方法可得到良好的结果。实际测量中,地形崎岖不平、飞行高度突变等常见现象会导致高度修正后的结果仍存在偏差甚至错误。基于条带模型构设崎岖地形条件下的反演方程组... 在航空γ测量中,当地形平坦且飞行高度变化不大时,采用传统的高度修正方法可得到良好的结果。实际测量中,地形崎岖不平、飞行高度突变等常见现象会导致高度修正后的结果仍存在偏差甚至错误。基于条带模型构设崎岖地形条件下的反演方程组,应用Tikhonov正则化方法求解可得到地面放射性核素的面活度浓度。Tikhonov正则化方法的应用结果表明:随机噪声较小时,采用广义交叉验证(generalized cross validation,GCV)方法选取正则化参数得到的反演结果较好;随机噪声较大时,采用L曲线方法选取正则化参数得到的反演结果较好。与传统高度修正方法的计算结果相比该方法好,且适用于飞行高度变化较大的情形。 展开更多
关键词 tikhonov正则化 反演 航空γ测量 高度修正
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用Tikhonov正则化方法同时反演对流扩散方程的对流速度和源函数
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作者 周子融 杨柳 王清艳 《四川大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第1期15-24,共10页
在给定两个附加观测数据的条件下,本文基于Tikhonov正则化方法研究了对流扩散方程的对流速度和源函数的同时反演问题.鉴于原问题是一个初始值非零的对流扩散方程,本文通过将初始值转化为源项得到了一个组合源项,首先将原问题转化为一个... 在给定两个附加观测数据的条件下,本文基于Tikhonov正则化方法研究了对流扩散方程的对流速度和源函数的同时反演问题.鉴于原问题是一个初始值非零的对流扩散方程,本文通过将初始值转化为源项得到了一个组合源项,首先将原问题转化为一个具有齐次条件的对流扩散问题.由于所得问题是不适定的,本文进而利用Tikhonov正则化方法构建了相应的极小化目标泛函,得到了问题最优解的存在性和应满足的必要条件.最后,对终端时刻较小的特殊情形,本文证明了最优解的唯一性和稳定性. 展开更多
关键词 对流扩散方程 反问题 源函数 tikhonov正则化方法
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分数阶椭圆方程反边值问题的分数Tikhonov正则化方法
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作者 张潇 张宏武 《数学物理学报(A辑)》 CSCD 北大核心 2024年第4期978-993,共16页
该文研究了Tricomi-Gellerstedt-Keldysh型分数阶椭圆方程的反边值问题.对于该不适定问题,建立了条件稳定性结果.基于问题的不适定性,构造了分数Tikhonov正则化方法,以恢复解对测量数据的连续依赖性.在正则化参数的先验和后验选取规则下... 该文研究了Tricomi-Gellerstedt-Keldysh型分数阶椭圆方程的反边值问题.对于该不适定问题,建立了条件稳定性结果.基于问题的不适定性,构造了分数Tikhonov正则化方法,以恢复解对测量数据的连续依赖性.在正则化参数的先验和后验选取规则下,分别给出并证明了相应的Hölder型收敛性结果.最后,通过两个数值例子验证了分数Tikhonov正则化方法的模拟效果.数值结果表明,该方法能稳定有效地处理文中反问题. 展开更多
关键词 反边值问题 分数阶椭圆方程 分数tikhonov正则化 先验和后验收敛性估计 数值模拟
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Composition Analysis and Identification of Ancient Glass Products Based on L1 Regularization Logistic Regression
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作者 Yuqiao Zhou Xinyang Xu Wenjing Ma 《Applied Mathematics》 2024年第1期51-64,共14页
In view of the composition analysis and identification of ancient glass products, L1 regularization, K-Means cluster analysis, elbow rule and other methods were comprehensively used to build logical regression, cluste... In view of the composition analysis and identification of ancient glass products, L1 regularization, K-Means cluster analysis, elbow rule and other methods were comprehensively used to build logical regression, cluster analysis, hyper-parameter test and other models, and SPSS, Python and other tools were used to obtain the classification rules of glass products under different fluxes, sub classification under different chemical compositions, hyper-parameter K value test and rationality analysis. Research can provide theoretical support for the protection and restoration of ancient glass relics. 展开更多
关键词 Glass Composition L1 regularization Logistic Regression Model K-Means Clustering Analysis Elbow Rule Parameter Verification
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改进Tikhonov正则化方法在结构激励识别与响应重构中的应用
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作者 周雪文 彭珍瑞 《机械科学与技术》 CSCD 北大核心 2024年第9期1469-1476,共8页
为了改善传递矩阵的病态性,实现利用结构有限测量信息对结构外部激励与未知响应的有效重构,提出了一种用于结构激励识别与响应重构的改进Tikhonov正则化方法。首先,基于状态空间模型构建传递矩阵,并推导结构外部激励识别与响应重构方程... 为了改善传递矩阵的病态性,实现利用结构有限测量信息对结构外部激励与未知响应的有效重构,提出了一种用于结构激励识别与响应重构的改进Tikhonov正则化方法。首先,基于状态空间模型构建传递矩阵,并推导结构外部激励识别与响应重构方程。其次,采用改进Tikhonov正则化方法改善传递矩阵的病态性,得到激励方程的正则化解,并结合结构需重构位置对应的传递矩阵重构未知加速度响应。最后,分别对平面二维桁架和简支梁进行数值仿真和试验分析,验证所提方法的可行性。结果表明所提方法能够改善传递矩阵的病态性,提高结构激励识别与响应重构的精度。 展开更多
关键词 激励识别 响应重构 状态空间 传递矩阵 正则化
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Convergent Data-Driven Regularizations for CT Reconstruction
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作者 Samira Kabri Alexander Auras +4 位作者 Danilo Riccio Hartmut Bauermeister Martin Benning Michael Moeller Martin Burger 《Communications on Applied Mathematics and Computation》 EI 2024年第2期1342-1368,共27页
The reconstruction of images from their corresponding noisy Radon transform is a typical example of an ill-posed linear inverse problem as arising in the application of computerized tomography(CT).As the(naive)solutio... The reconstruction of images from their corresponding noisy Radon transform is a typical example of an ill-posed linear inverse problem as arising in the application of computerized tomography(CT).As the(naive)solution does not depend on the measured data continuously,regularization is needed to reestablish a continuous dependence.In this work,we investigate simple,but yet still provably convergent approaches to learning linear regularization methods from data.More specifically,we analyze two approaches:one generic linear regularization that learns how to manipulate the singular values of the linear operator in an extension of our previous work,and one tailored approach in the Fourier domain that is specific to CT-reconstruction.We prove that such approaches become convergent regularization methods as well as the fact that the reconstructions they provide are typically much smoother than the training data they were trained on.Finally,we compare the spectral as well as the Fourier-based approaches for CT-reconstruction numerically,discuss their advantages and disadvantages and investigate the effect of discretization errors at differentresolutions. 展开更多
关键词 Inverse problems regularization Computerized tomography(CT) Machine learning
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Impact Force Localization and Reconstruction via ADMM-based Sparse Regularization Method
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作者 Yanan Wang Lin Chen +3 位作者 Junjiang Liu Baijie Qiao Weifeng He Xuefeng Chen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第3期170-188,共19页
In practice,simultaneous impact localization and time history reconstruction can hardly be achieved,due to the illposed and under-determined problems induced by the constrained and harsh measuring conditions.Although ... In practice,simultaneous impact localization and time history reconstruction can hardly be achieved,due to the illposed and under-determined problems induced by the constrained and harsh measuring conditions.Although l_(1) regularization can be used to obtain sparse solutions,it tends to underestimate solution amplitudes as a biased estimator.To address this issue,a novel impact force identification method with l_(p) regularization is proposed in this paper,using the alternating direction method of multipliers(ADMM).By decomposing the complex primal problem into sub-problems solvable in parallel via proximal operators,ADMM can address the challenge effectively.To mitigate the sensitivity to regularization parameters,an adaptive regularization parameter is derived based on the K-sparsity strategy.Then,an ADMM-based sparse regularization method is developed,which is capable of handling l_(p) regularization with arbitrary p values using adaptively-updated parameters.The effectiveness and performance of the proposed method are validated on an aircraft skin-like composite structure.Additionally,an investigation into the optimal p value for achieving high-accuracy solutions via l_(p) regularization is conducted.It turns out that l_(0.6)regularization consistently yields sparser and more accurate solutions for impact force identification compared to the classic l_(1) regularization method.The impact force identification method proposed in this paper can simultaneously reconstruct impact time history with high accuracy and accurately localize the impact using an under-determined sensor configuration. 展开更多
关键词 Impact force identification Non-convex sparse regularization Alternating direction method of multipliers Proximal operators
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Enhanced Differentiable Architecture Search Based on Asymptotic Regularization
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作者 Cong Jin Jinjie Huang +1 位作者 Yuanjian Chen Yuqing Gong 《Computers, Materials & Continua》 SCIE EI 2024年第2期1547-1568,共22页
In differentiable search architecture search methods,a more efficient search space design can significantly improve the performance of the searched architecture,thus requiring people to carefully define the search spa... In differentiable search architecture search methods,a more efficient search space design can significantly improve the performance of the searched architecture,thus requiring people to carefully define the search space with different complexity according to various operations.Meanwhile rationalizing the search strategies to explore the well-defined search space will further improve the speed and efficiency of architecture search.With this in mind,we propose a faster and more efficient differentiable architecture search method,AllegroNAS.Firstly,we introduce a more efficient search space enriched by the introduction of two redefined convolution modules.Secondly,we utilize a more efficient architectural parameter regularization method,mitigating the overfitting problem during the search process and reducing the error brought about by gradient approximation.Meanwhile,we introduce a natural exponential cosine annealing method to make the learning rate of the neural network training process more suitable for the search procedure.Moreover,group convolution and data augmentation are employed to reduce the computational cost.Finally,through extensive experiments on several public datasets,we demonstrate that our method can more swiftly search for better-performing neural network architectures in a more efficient search space,thus validating the effectiveness of our approach. 展开更多
关键词 Differentiable architecture search allegro search space asymptotic regularization natural exponential cosine annealing
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Trigonometric Regularization and Continuation Method Based Time-Optimal Control of Hypersonic Vehicles
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作者 LIN Yujie HAN Yanhua 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第S01期52-59,共8页
Aiming at the time-optimal control problem of hypersonic vehicles(HSV)in ascending stage,a trigonometric regularization method(TRM)is introduced based on the indirect method of optimal control.This method avoids analy... Aiming at the time-optimal control problem of hypersonic vehicles(HSV)in ascending stage,a trigonometric regularization method(TRM)is introduced based on the indirect method of optimal control.This method avoids analyzing the switching function and distinguishing between singular control and bang-bang control,where the singular control problem is more complicated.While in bang-bang control,the costate variables are unsmooth due to the control jumping,resulting in difficulty in solving the two-point boundary value problem(TPBVP)induced by the indirect method.Aiming at the easy divergence when solving the TPBVP,the continuation method is introduced.This method uses the solution of the simplified problem as the initial value of the iteration.Then through solving a series of TPBVP,it approximates to the solution of the original complex problem.The calculation results show that through the above two methods,the time-optimal control problem of HSV in ascending stage under the complex model can be solved conveniently. 展开更多
关键词 hypersonic vehicle(HSV) optimal control trigonometric regularization method(TRM) continuation method
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高阶数值导数的分数阶Tikhonov正则化方法
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作者 张龙 《理论数学》 2024年第7期53-60,共8页
在本文中,我们关注高阶数值导数问题,该问题是不适定的。为了解决这一反问题,我们提出了分数阶Tikhonov正则化方法,用于从一维噪声数据中计算高阶数值导数。本文先用Fourier变换求出问题的精确解,再用分数阶Tikhonov正则化方法构造出问... 在本文中,我们关注高阶数值导数问题,该问题是不适定的。为了解决这一反问题,我们提出了分数阶Tikhonov正则化方法,用于从一维噪声数据中计算高阶数值导数。本文先用Fourier变换求出问题的精确解,再用分数阶Tikhonov正则化方法构造出问题的正则化解,最后讨论了先验正则化参数选择规则下精确解与正则化近似解的误差估计。 展开更多
关键词 数值微分 反问题 分数阶tikhonov正则化 误差估计
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Low-Rank Multi-View Subspace Clustering Based on Sparse Regularization
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作者 Yan Sun Fanlong Zhang 《Journal of Computer and Communications》 2024年第4期14-30,共17页
Multi-view Subspace Clustering (MVSC) emerges as an advanced clustering method, designed to integrate diverse views to uncover a common subspace, enhancing the accuracy and robustness of clustering results. The signif... Multi-view Subspace Clustering (MVSC) emerges as an advanced clustering method, designed to integrate diverse views to uncover a common subspace, enhancing the accuracy and robustness of clustering results. The significance of low-rank prior in MVSC is emphasized, highlighting its role in capturing the global data structure across views for improved performance. However, it faces challenges with outlier sensitivity due to its reliance on the Frobenius norm for error measurement. Addressing this, our paper proposes a Low-Rank Multi-view Subspace Clustering Based on Sparse Regularization (LMVSC- Sparse) approach. Sparse regularization helps in selecting the most relevant features or views for clustering while ignoring irrelevant or noisy ones. This leads to a more efficient and effective representation of the data, improving the clustering accuracy and robustness, especially in the presence of outliers or noisy data. By incorporating sparse regularization, LMVSC-Sparse can effectively handle outlier sensitivity, which is a common challenge in traditional MVSC methods relying solely on low-rank priors. Then Alternating Direction Method of Multipliers (ADMM) algorithm is employed to solve the proposed optimization problems. Our comprehensive experiments demonstrate the efficiency and effectiveness of LMVSC-Sparse, offering a robust alternative to traditional MVSC methods. 展开更多
关键词 CLUSTERING Multi-View Subspace Clustering Low-Rank Prior Sparse regularization
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3D density inversion of gravity gradient data using the extrapolated Tikhonov regularization 被引量:4
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作者 刘金钊 柳林涛 +1 位作者 梁星辉 叶周润 《Applied Geophysics》 SCIE CSCD 2015年第2期137-146,273,共11页
We use the extrapolated Tikhonov regularization to deal with the ill-posed problem of 3D density inversion of gravity gradient data. The use of regularization parameters in the proposed method reduces the deviations b... We use the extrapolated Tikhonov regularization to deal with the ill-posed problem of 3D density inversion of gravity gradient data. The use of regularization parameters in the proposed method reduces the deviations between calculated and observed data. We also use the depth weighting function based on the eigenvector of gravity gradient tensor to eliminate undesired effects owing to the fast attenuation of the position function. Model data suggest that the extrapolated Tikhonov regularization in conjunction with the depth weighting function can effectively recover the 3D distribution of density anomalies. We conduct density inversion of gravity gradient data from the Australia Kauring test site and compare the inversion results with the published research results. The proposed inversion method can be used to obtain the 3D density distribution of underground anomalies. 展开更多
关键词 extrapolated tikhonov regularization depth weighting gravity gradient tensor eieenvector
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利用GPS垂直位移反演区域陆地水储量变化的TSVD-Tikhonov正则化方法 被引量:1
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作者 钟波 李贤炮 +2 位作者 李建成 汪海洪 丁剑 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2023年第3期997-1014,共18页
利用GPS垂直位移反演区域陆地水储量变化(TWSC)属于典型的病态问题,其关键是如何进行稳定求解并提高反演结果的精度和可靠性.本文引入TSVD-Tikhonov组合正则化方法对利用GPS垂直位移反演区域TWSC的病态问题进行求解,并以四川省TWSC反演... 利用GPS垂直位移反演区域陆地水储量变化(TWSC)属于典型的病态问题,其关键是如何进行稳定求解并提高反演结果的精度和可靠性.本文引入TSVD-Tikhonov组合正则化方法对利用GPS垂直位移反演区域TWSC的病态问题进行求解,并以四川省TWSC反演为例进行分析与验证.首先,通过数值模拟对TSVD、Tikhonov和TSVD-Tikhonov正则化方法采用不同正则化参数选取策略(RMSE最小准则、GCV法和L-curve法)进行反演,结果显示基于TSVD-Tikhonov正则化反演的TWSC比单独使用TSVD或Tikhonov正则化反演结果的精度和可靠性更高,这三种正则化方法反演2005年1月至12月的TWSC差值的平均STD分别为14.97 mm、7.03 mm和5.04 mm.其次,利用中国地壳运动观测网络(CMONOC)的72个GPS测站的垂直位移数据,基于TSVD-Tikhonov正则化反演了四川省2010年12月至2021年2月的TWSC时间序列,结果表明GPS反演的TWSC与GRACE/GFO Mascon模型(JPL、CSR和GSFC)的空间分布特征及季节性变化符合较好,但其TWSC信号的振幅比GRACE/GFO Mascon模型更强.最后,采用广义三角帽方法(GTCH)融合不同类型的降水、蒸散发和径流数据,并根据水量平衡方程计算的dTWSC/dt序列(PER-dS/dt)对GPS反演的dTWSC/dt序列(GPS-dS/dt)和GRACE/GFO Mascon模型融合的dTWSC/dt序列(GRACE/GFO-dS/dt)进行验证,结果表明这三类dTWSC/dt序列的季节性变化符合较好,平滑后GPS-dS/dt和GRACE/GFO-dS/dt序列与PER-dS/dt序列的相关系数分别为0.78和0.87,但GPS相比GRACE/GFO对降水变化的响应更为敏感.本文研究证明了TSVD-Tikhonov组合正则化方法能够提高GPS垂直位移反演区域TWSC的精度和可靠性,同时也表明GPS观测数据对局部水质量负荷变化更为敏感,可作为GRACE/GFO反演区域TWSC的有益补充. 展开更多
关键词 GPS垂直位移 区域陆地水储量变化 TSVD-tikhonov正则化 广义三角帽方法 GRACE/GFO 四川省
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Application of Tikhonov regularization method to wind retrieval from scatterometer data Ⅱ: cyclone wind retrieval with consideration of rain 被引量:6
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作者 钟剑 黄思训 +2 位作者 费建芳 杜华栋 张亮 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第6期263-268,共6页
According to the conclusion of the simulation experiments in paper I, the Tikhonov regularization method is applied to cyclone wind retrieval with a rain-effect-considering geophysical model function (called CMF+Rai... According to the conclusion of the simulation experiments in paper I, the Tikhonov regularization method is applied to cyclone wind retrieval with a rain-effect-considering geophysical model function (called CMF+Rain). The CMF+Rain model which is based on the NASA scatterometer-2 (NSCAT2) GMF is presented to compensate for the effects of rain on cyclone wind retrieval. With the multiple solution scheme (MSS), the noise of wind retrieval is effectively suppressed, but the influence of the background increases. It will cause a large wind direction error in ambiguity removal when the background error is large. However, this can be mitigated by the new ambiguity removal method of Tikhonov regularization as proved in the simulation experiments. A case study on an extratropical cyclone of hurricane observed with SeaWinds at 25-km resolution shows that the retrieved wind speed for areas with rain is in better agreement with that derived from the best track analysis for the GMF+Rain model, but the wind direction obtained with the two-dimensional variational (2DVAR) ambiguity removal is incorrect. The new method of Tikhonov regularization effectively improves the performance of wind direction ambiguity removal through choosing appropriate regularization parameters and the retrieved wind speed is almost the same as that obtained from the 2DVAR. 展开更多
关键词 SCATTEROMETER tikhonov regularization cyclone wind retrieval rain effects
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基于分数阶Tikhonov正则化的激光吸收光谱燃烧场二维重建光路优化研究 被引量:1
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作者 庞维煦 李宁 +4 位作者 黄孝龙 康杨 李灿 范旭东 翁春生 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第3期277-287,共11页
为探究基于激光吸收光谱技术的燃烧场二维测量光路布置方式,实现有限投影下更精确的燃烧场二维重建,根据分数阶微积分理论,提出一种基于分数阶Tikhonov正则化的光路优化方法.将经典的整数阶Tikhonov正则化推广到分数阶模式,建立了基于... 为探究基于激光吸收光谱技术的燃烧场二维测量光路布置方式,实现有限投影下更精确的燃烧场二维重建,根据分数阶微积分理论,提出一种基于分数阶Tikhonov正则化的光路优化方法.将经典的整数阶Tikhonov正则化推广到分数阶模式,建立了基于分数阶Tikhonov正则化的光路设计目标函数.利用遗传算法分析(0,1)范围内不同阶数的计算结果,得到最佳光路布置方式.采用近红外波段7185.6 cm^(-1)的H_(2)O特征吸收谱线结合20条测试光路对10×10离散化网格区域进行计算,对比分析五种光路布置方式对多种分布模型的重建结果,结果表明,基于分数阶Tikhonov正则化的光路布置方式具有最佳重建效果.研究结果对有限投影条件下激光吸收光谱二维测量光路的优化设计理论研究具有重要意义,可以促进激光吸收光谱技术在复杂发动机燃烧场二维重建及燃烧效率提升方面的应用. 展开更多
关键词 激光吸收光谱 二维重建 分数阶tikhonov正则化 光路优化
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Some studies on the Tikhonov regularization method with additional assumptions for noise data 被引量:3
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作者 贺国强 尹秀玲 《Journal of Shanghai University(English Edition)》 CAS 2007年第2期126-131,共6页
In this paper, the Tikhonov regularization method was used to solve the nondegenerate compact hnear operator equation, which is a well-known ill-posed problem. Apart from the usual error level, the noise data were sup... In this paper, the Tikhonov regularization method was used to solve the nondegenerate compact hnear operator equation, which is a well-known ill-posed problem. Apart from the usual error level, the noise data were supposed to satisfy some additional monotonic condition. Moreover, with the assumption that the singular values of operator have power form, the improved convergence rates of the regularized solution were worked out. 展开更多
关键词 ill-posed equation tikhonov regularization method monotonic condition convergence rates
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Bathymetry inversion using the modifi ed gravitygeologic method:application of the rectangular prism model and Tikhonov regularization 被引量:5
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作者 Xing Jian Chen Xin-Xi Ma Long 《Applied Geophysics》 SCIE CSCD 2020年第3期377-389,共13页
Bathymetry data are usually obtained via single-beam or multibeam sounding;however,these methods exhibit low efficiency and coverage and are dependent on various parameters,including the condition of the vessel and se... Bathymetry data are usually obtained via single-beam or multibeam sounding;however,these methods exhibit low efficiency and coverage and are dependent on various parameters,including the condition of the vessel and sea state.To overcome these limitations,we propose a method for marine bathymetry inversion based on the satellite altimetry gravity anomaly data as a modification of the gravity-geologic method(GGM),which is a conventional terrain inversion method based on gravity data.In accordance with its principle,the modified method adopts a rectangular prism model for modeling the short-wavelength gravity anomaly and the Tikhonov regularization method to integrate the geophysical constraints,including the a priori water depth data and characteristics of the sea bottom relief.The a priori water depth data can be obtained based on the measurement data obtained from a ship,borehole information,etc.,and the existing bathymetry/terrain model can be considered as the initial model.Marquardt’s method is used during the inversion process,and the regularization parameter can be adaptively determined.The model test and application to the West Philippine Basin indicate the feasibility and eff ectiveness of the proposed method.The results indicate the capability of the proposed method to improve the overall accuracy of the water depth data.Then,the proposed method can be used to conduct a preliminary study of the ocean depths.Additionally,the results show that in the improved GGM,the density diff erence parameter has lost its original physical meaning,and it will not have a great impact on the inversion process.Based on the boundedness of the study area,the inversion result may exhibit a lower confi dence level near the margin than that near the center.Furthermore,the modifi ed GGM is time-and memory-intensive when compared with the conventional GGM. 展开更多
关键词 BATHYMETRY GRAVITY INVERSION tikhonov regularization
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A modified Tikhonov regularization method for a Cauchy problem of a time fractional diffusion equation 被引量:1
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作者 CHENG Xiao-liang YUAN Le-le LIANG Ke-wei 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2019年第3期284-308,共25页
In this paper,we consider a Cauchy problem of the time fractional diffusion equation(TFDE)in x∈[0,L].This problem is ubiquitous in science and engineering applications.The illposedness of the Cauchy problem is explai... In this paper,we consider a Cauchy problem of the time fractional diffusion equation(TFDE)in x∈[0,L].This problem is ubiquitous in science and engineering applications.The illposedness of the Cauchy problem is explained by its solution in frequency domain.Furthermore,the problem is formulated into a minimization problem with a modified Tikhonov regularization method.The gradient of the regularization functional based on an adjoint problem is deduced and the standard conjugate gradient method is presented for solving the minimization problem.The error estimates for the regularized solutions are obtained under Hp norm priori bound assumptions.Finally,numerical examples illustrate the effectiveness of the proposed method. 展开更多
关键词 CAUCHY problem time-fractional diffusion equation a MODIFIED tikhonov regularization METHOD CONJUGATE gradient METHOD error estimates
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Representing surface wind stress response to mesoscale SST perturbations in western coast of South America using Tikhonov regularization method 被引量:2
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作者 CUI Chaoran ZHANG Rong-Hua +1 位作者 WANG Hongna WEI Yanzhou 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2020年第3期679-694,共16页
Interaction between mesoscale perturbations of sea surface temperature(SSTmeso)and wind stress(WSmeso)has great influences on the ocean upwelling system and turbulent mixing in the atmospheric boundary layer.Using dai... Interaction between mesoscale perturbations of sea surface temperature(SSTmeso)and wind stress(WSmeso)has great influences on the ocean upwelling system and turbulent mixing in the atmospheric boundary layer.Using daily Quik-SCAT wind speed data and AMSR-E SST data,SSTmeso and WSmeso fields in the western coast of South America are extracted by using a locally weighted regression method(LOESS).The spatial patterns of SSTmeso and WSmeso indicate strong mesoscale SST-wind stress coupling in the region.The coupling coefficient between SSTmeso and WSmeso is about 0.0095 N/(m^2·℃)in winter and 0.0082 N/(m^2·℃)in summer.Based on mesoscale coupling relationships,the mesoscale perturbations of wind stress divergence(Div(WSmeso))and curl(Curl(WSmeso))can be obtained from the SST gradient perturbations,which can be further used to derive wind stress vector perturbations using the Tikhonov regularization method.The computational examples are presented in the western coast of South America and the patterns of the reconstructed WS meso are highly consistent with SSTmeso,but the amplitude can be underestimated significantly.By matching the spatially averaged maximum standard deviations of reconstructed WSmeso magnitude and observations,a reasonable magnitude of WSmeso can be obtained when a rescaling factor of 2.2 is used.As current ocean models forced by prescribed wind cannot adequately capture the mesoscale wind stress response,the empirical wind stress perturbation model developed in this study can be used to take into account the feedback effects of the mesoscale wind stress-SST coupling in ocean modeling.Further applications are discussed for taking into account the feedback effects of the mesoscale coupling in largescale climate models and the uncoupled ocean models. 展开更多
关键词 MESOSCALE AIR-SEA coupling tikhonov’s regularization method WESTERN COAST of South AMERICA
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