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On construction of strong orthogonal arrays and column-orthogonal strong orthogonal arrays of strength two plus

Science China Mathematics 2025年第5期68卷 1219-1242页

作者： Bochuan Jiang Yaping Wang Fasheng Sun School of Mathematics and Statistics Beijing Jiaotong UniversityBeijing100044China Key Laboratory of Advanced Theory and Application in Statistics and Data Science Ministry of EducationSchool of StatisticsEast China Normal UniversityShanghai200062China Key Laboratory for Applied Statistics of Ministry of Education and School of Mathematics and Statistics Northeast Normal UniversityChangchun130024China

Computer experiments require space-filling designs with good low-dimensional projection *** orthogonal arrays are a type of space-filling design that provides better stratifications in low dimensions than ordinary orthogonal *** this paper,we address the problem of constructing strong orthogonal arrays and column-orthogonal strong orthogonal arrays of strength two *** methods typically rely on regular designs or specific nonregular designs as base orthogonal arrays,limiting the sizes of the final ***,we propose two general methods that are easy to implement and applicable to a wide range of base orthogonal *** methods produce space-filling designs that can accommodate a large number of factors,provide significant flexibility in terms of run sizes,and possess appealing low-dimensional projection ***,these designs are ideal for computer experiments.

关键词： computer experiment difference scheme strong orthogonal array column-orthogonality space-filling property

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Byzantine-robust distributed support vector machine

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Science China Mathematics 2025年第3期68卷 707-728页

作者： Xiaozhou Wang Weidong Liu Xiaojun Mao School of Statistics East China Normal UniversityShanghai 200062China Key Laboratory of Advanced Theory and Application in Statistics and Data Science(Ministry of Education) East China Normal UniversityShanghai 200062China School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Artificial Intelligence(Ministry of Education) Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Scientific and Engineering Computing(Ministry of Education) Shanghai Jiao Tong UniversityShanghai 200240China

The development of information technology brings diversification of data sources and large-scale data sets and calls for the exploration of distributed learning algorithms. In distributed systems, some local machines may behave abnormally and send arbitrary information to the central machine(known as Byzantine failures), which can invalidate the distributed algorithms based on the assumption of faultless systems. This paper studies Byzantine-robust distributed algorithms for support vector machines(SVMs) in the context of binary classification. Despite a vast literature on Byzantine problems, much less is known about the theoretical properties of Byzantine-robust SVMs due to their unique challenges. In this paper, we propose two distributed gradient descent algorithms for SVMs. The median and trimmed mean operations in aggregation can effectively defend against Byzantine failures. Theoretically, we show the convergence of the proposed estimators and provide the statistical error rates. After a certain number of iterations, our estimators achieve near-optimal rates. Simulation studies and real data analysis are conducted to demonstrate the performance of the proposed Byzantine-robust distributed algorithms.

关键词： Byzantine robustness convergence distributed learning support vector machine

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A model-free feature extraction procedure for interval-valued time series prediction

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Soft Computing 2025年第6期29卷 2727-2741页

作者： Tian, Wan Qin, Zhongfeng Hu, Tao School of Economics and Management Beihang University Beijing100191 China Beijing100191 China Key Laboratory of Advanced Theory and Application in Statistics and Data Science Ministry of Education Shanghai China School of Mathematical Sciences Capital Normal University Beijing100048 China

We present a novel feature extraction procedure to predict interval-valued time series by combing transfer learning and imaging approaches. Initially, we represent interval-valued time series as a bivariate point-valued time series, and then transform each time series into images by employing imaging approaches such as recurrence plot, gramian angular summation/difference field, and Markov transition field, thereby obtaining an image dataset containing four classes. Based on this dataset, we train multiple candidate feature extraction networks, specifically ResNet with varying layers. Then we choose the penultimate layer of the feature extraction networks to extract the most relevant features from the images. To formulate prediction, we integrate the extracted features into a traditional prediction model. The proposed method are evaluated on three data-generating processes as well as the S&P 500 index, and the experimental results demonstrate a notable improvement in prediction performance compared to existing methods. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： Feature Selection

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基于织构工程优化的n型Ag2Se薄膜热电性能增强研究（英文）

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Science China Materials 2025年第5期68卷 1630-1637页

作者：张新洋贺丹琪陈李莎黄同露叶先锋李浩天朱婉婷聂晓蕾余健张玉魏平赵文俞张清杰 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics Wuhan University of Technology School of Materials Science and Engineering Jiujiang University Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory

柔性热电发电技术日益被认为是为可穿戴电子设备供电的有效解决方案.然而,n型柔性薄膜的性能局限性限制了其更广泛的应用.本研究通过织构工程技术获得了高性能n型Ag2Se薄膜,在300 K时,功率因子高达2.14 mW m-1K-2.我们采用简单的蒸发镀... 详细信息

柔性热电发电技术日益被认为是为可穿戴电子设备供电的有效解决方案.然而,n型柔性薄膜的性能局限性限制了其更广泛的应用.本研究通过织构工程技术获得了高性能n型Ag2Se薄膜,在300 K时,功率因子高达2.14 mW m-1K-2.我们采用简单的蒸发镀膜技术,结合前驱体调控策略,制备了（201）取向的n型Ag2Se薄膜.实验和理论分析均表明,这种择优取向的Ag2Se薄膜具有高迁移率和高Seebeck系数.此外,纳米孔和随机面内取向结构的引入,显著散射了不同波长声子,从而使Ag2Se热导率进一步降低.最终,在363 K时,Ag2Se薄膜ZT值高达0.73.本研究不仅提出了一种调控Ag2Se薄膜晶体取向的策略方法,还为开发高性能热电薄膜材料创造了新的前景.

关键词： Ag2Se film texture engineering preferred orientation electrical properties thermoelectric performance

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The role of γ/γ interfacial spacing on the tensile behavior in lamellar TiAl alloy via molecular dynamics simulations

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Acta Mechanica Sinica 2025年第2期41卷 1-6页

作者： Xiong Zhou Shiping Wang Zhongtao Lu Xiege Huang Xiaobin Feng Jiayi Fu Wenjuan Li Pengcheng Zhai Guodong Li Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics School of ScienceWuhan University of TechnologyWuhan 430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

The lamellar microstructure is one of the most typical microstructures of TiAl *** are threeγ/γinterfaces with different microstructures in lamellarγ-TiAl *** this work,we investigated the deformation processes of lamellarγ-TiAl alloys with different interfacial spacing(λ)via uniaxial tensile loading using molecular dynamics simulations,including true twin(TT),pseudo-twin(PT),rotational boundary(RB),and the mixed structure(TT∥PT∥RB).The results show that in all lamellarγ-TiAl samples,the Shockley partial dislocation prefers to nucleate in the region between two neighboring ***,dislocations move towards,crossing theγ/γ***,the dislocation slippage leads to the destruction of the interface,resulting in cracks and structural *** the decrease ofλ,the ultimate strength slightly increases in the TT or PT structure ofγ-TiAl,which follows the Hall-Petch *** in general,the interfacial spacing has a slight effect on the ultimate strengths of these four structures ofγ-TiAl.

关键词： Lamellarγ-TiAl alloys γ/γinterface Ultimate strength Interfacial spacing

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Knowledge Transfer Across Modalities for Weakly Supervised Point Cloud Semantic Segmentation

Knowledge Transfer Across Modalities for Weakly Supervised P...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Zihan Wang Yunhang Shen Mengtian Li Ke Li Xing Sun Shaohui Lin Lizhuang Ma East China Normal University Tencent Youtu Lab Shanghai University Key Laboratory of Advanced Theory and Application in Statistics and Data Science

ISBN: (数字)9798350368741

ISBN: (纸本)9798350368758

Current weakly supervised point cloud semantic segmentation struggles with insufficient utilization of limited annotations in unimodal representation learning due to the sparse and textureless nature of point clouds. In this work, we leverage cross-modality information by transferring knowledge from image and text sources to the point cloud network. The intuition is that images contribute rich texture, color, and discriminative information, complementing point clouds to boost semantic segmentation performance. To reduce extensive computational resources for cross-modality fusion, we introduce the Multi-Scale Deformable Knowledge Transfer, an innovative training scheme that optimizes and extends the one-to-one mapping to flexible one-to-many relations between multi-modal data. Furthermore, we employ pre-trained image-text models to generate pseudo labels for point clouds and construct positive and negative samples for semantic contrastive regularization, facilitating the full exploitation of unlabeled data. The experimental results evaluated on SemanticKITTI and nuScenes demonstrate substantial improvements, achieving an average gain of 3.8% over the previous weakly supervised methods, and comparable performances to fully supervised approaches.

关键词： Point cloud compression Training Representation learning Weak supervision Three-dimensional displays Semantic segmentation Semantics Signal processing Speech processing Knowledge transfer

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Dynamics analysis of a V-shaped microcantilever based on finite difference method 8

Dynamics analysis of a V-shaped microcantilever based on fin...

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2024 8th International Conference on Mechanics, Mathematics and Applied Physics, ICMMAP 2024

作者： Zhang, Bangzhi Zhou, Xilong Yang, Changyun College of Energy and Mining Engineering Shandong University of Science and Technology Qingdao266590 China Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics Wuhan University of Technology Wuhan430070 China

The V-shaped microcantilever is advantageous for its high sensitivity and low stiffness, making it suitable as an atomic force microscope probe for characterizing the mechanical properties of soft materials. However, due to the complex geometry and the nonlinear tip-sample interaction, the analysis of the dynamic characteristics of a V-shaped microcantilever is generally difficult. In this paper, the finite difference computational formula of the governing formula and boundary conditions of a V-shaped microcantilever is derived and the analysis of its dynamic characteristics is performed. The amplitude and phase spectroscopy curves of the V-shaped microcantilever, as well as the frequency response, are obtained. The developed finite difference computational formula provides an effective approach for dynamics analysis and the optimization design for the V-shaped microcantilever. © Published under licence by IOP Publishing Ltd.

关键词： Nanocantilevers

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Customized priors for enhanced multispectral and hyperspectral image sharpening

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Information Fusion 2025年 122卷

作者： Zhang, Junkang Zhang, Haoyang Wang, Tingting Fang, Faming Zhang, Guixu Xu, Ming School of Computer Science and Technology East China Normal University Shanghai200062 China Key Laboratory of Advanced Theory and Application in Statistics and Data Science Shanghai China

In recent years, deep unfolding (DU) models have gained significant traction in multi-source image fusion applications, including remote sensing pansharpening and the integration of multispectral and hyperspectral images, owing to their enhanced interpretability. However, despite embedding physical degradation models, these DU models still rely on implicit learning for their priors, which can impede interpretability. In this paper, we present a novel image fusion model based on maximum a posterior (MAP) framework. This model enhances interpretability and fusion performance by incorporating two innovative prior modules. The first module employs codebook to capture the spectral traits of the target image, subsequently integrating these insights within our DU framework. The second module specializes in uncovering the intrinsic correlations between multi-source images, ensuring that the fusion process effectively leverages the rich, diverse information encoded within each modality. Specifically, we have effectively combined the self-similarity and cross-modal similarity paradigms into a unified cross image prior module. To counteract the redundancy present in images, we have integrated an agent mechanism that significantly simplifies the computational load of our prior module. Quantitative and qualitative experiments on multiple benchmark datasets demonstrate that the proposed method achieves more robustness and high-quality results than other state-of-the-art sharpening methods. © 2025 Elsevier B.V.

关键词： Miocene

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ON STOCHASTIC CONTROL PROBLEMS WITH HIGHER-ORDER MOMENTS

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SIAM Journal on Control and Optimization 2025年第3期63卷 1560-1589页

作者： Wang, Yike Liu, Jingzhen Bensoussan, Alain Cedric Yiu, Ka-Fai Wei, Jiaqin School of Finance Chongqing Technology and Business University Chongqing China China Institute for Actuarial Science Central University of Finance and Economics Beijing China SNaveen Jindal School of Management University of Texas at Dallas DallasTX75080 United States Department of Applied Mathematics Hong Kong Polytechnic University Hong Kong Key Laboratory of Advanced Theory and Application in Statistics and Data Science-MOE School of Statistics East China Normal University Shanghai China

In this paper, we focus on a class of time-inconsistent stochastic control problems, where the objective function includes the mean and several higher-order central moments of the terminal value of state. To tackle the time-inconsistency, we seek both the closed-loop and the open-loop Nash equilibrium controls as time-consistent solutions. We establish a partial differential equation (PDE) system for deriving a closed-loop Nash equilibrium control, which does not include the equilibrium value function and is different from the extended Hamilton-Jacobi-Bellman (HJB) equations as in Bj\" ork, Khapko, and Murgoci [Finance Stoch., 21 (2017), pp. 331-360]. We show that our PDE system is equivalent to the extended HJB equations that seem difficult to solve for our higher-order moment problems. In deriving an open-loop Nash equilibrium control, due to the nonseparable higher-order moments in the objective function, we make some moment estimates in addition to the standard perturbation argument for developing a maximum principle. Then, the problem is reduced to solving a flow of forward-backward stochastic differential equations. In particular, we investigate linear controlled dynamics and some objective functions affine in the mean. The closed-loop and the open-loop Nash equilibrium controls are identical, which are independent of the state value, the random path, and the preference on the odd-order central moments. By sending the highest order of central moments to infinity, we obtain the time-consistent solutions to some control problems whose objective functions include some penalty functions for deviation. © 2025 Society for Industrial and Applied Mathematics.

关键词： Stochastic control systems

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Damage characteristics of low-velocity impact of hybrid laminates made of thick- and thin-plies

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Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica 2025年第5期42卷 2595-2606页

作者： Zheng, Kaidong Chen, Hongda Cai, Wei Cao, Dongfeng Hu, Haixiao Li, Ruiqi Li, Shuxin National Energy Key Laboratory for New Hydrogen-ammonia Energy Technologies Foshan Xianhu Laboratory Foshan528200 China State Key Laboratory of Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics Wuhan University of Technology Wuhan430070 China Institute of Advanced Materials and Manufacturing Technology Wuhan University of Technology Wuhan430070 China

The ply level hybridization design employs multiple thin layers instead of a single thick layer, resulting in an increased complexity of the interface. To investigate the hybrid effect between thick and thin plies of laminated composites subjected to low-velocity impact loading, two hybrid laminates were designed based on the quasi-isotropic stacking sequence. The low-velocity impact (LVI) tests including the baseline laminate and hybrid laminates were carried out. The ultrasonic C-scan and de-ply technology were respectively used to make a nondestructive and destructive detection on laminates with impact damages. Impact damages were qualitatively and quantitatively evaluated based on the detection results. Subsequently, the performances and failure modes of compression after impact (CAI) were analyzed. Experimental results show that hybrid design of thick- and thin- plies makes full use of the damage suppression characteristics of thin-ply composite, improves the impact damage resistance of composite structures, reduces the projected delamination area and total interface delamination area, shortens the distance between the largest single delamination and the neutral layer, and significantly improves the CAI strength of composite structures. The outputs of this experimental research serves as an indication for the optimal design and safety evaluation of hybrid structures. © 2025 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.

关键词： Delamination

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