检索结果-南通市图书馆

Meta label associated loss for fine-grained visual recognition

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第6期67卷 230-247页

作者： Yanchao li Fu XIAO Hao li Qun li Shui YU School of Computer Science Nanjing University of Posts and Telecommunications School of Network Engineering Zhoukou Normal University School of Computer Science University of Technology Sydney

Recently, intensive attempts have been made to design robust models for fine-grained visual recognition, most notably are the impressive gains for training with noisy labels by incorporating a reweighting strategy into a meta-learning framework. However, it is limited to up or downweighting the contribution of an instance for label reweighting approaches in the learning process. To solve this issue, a novel noise-tolerant method with auxiliary web data is proposed. Specifically, first, the associations made from embeddings of well-labeled data with those of web data and back at the same class are measured. Next, its association probability is employed as a weighting fusion strategy into angular margin-based loss, which makes the trained model robust to noisy datasets. To reduce the influence of the gap between the well-labeled and noisy web data, a bridge schema is proposed via the corresponding loss that encourages the learned embeddings to be coherent. Lastly, the formulation is encapsulated into the meta-learning framework, which can reduce the overfitting of models and learn the network parameters to be noise-tolerant. Extensive experiments are performed on benchmark datasets, and the results clearly show the superiority of the proposed method over existing state-of-the-art approaches.

关键词： label associated loss weighting noisy samples fine-grained visual recognition noise-tolerant learning meta-learning

New insights into the pre-lithiation kinetics of single-crystalline Ni-rich cathodes for long-life li-ion batteries

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第3期9卷 556-564页

作者： Qiang Han Lele Cai Zhaofeng Yang Yanjie Hu Hao Jiang Chunzhong li Shanghai Engineering Research Center of Hierarchical Nanomaterials School of Chemical EngineeringEast China University of Science and TechnologyShanghai200237China Key Laboratory for Ultrafine Materials of Ministry of Education School of Materials Science and EngineeringEast China University of Science and TechnologyShanghai200237China

Developing single-crystalline Ni-rich cathodes is an effective strategy to improve the safety and cycle life of li-ion batteries(liBs).However,the easy-to-loss of li and O in high-temperature lithiation results in unsatisfactory ordered layered structure and ***,we demonstrate the synthesis of highly-ordered and fully-stoichiometric single-crystalline liNi_(0.83)Co_(0.12)Mn_(0.05)O_(2)(SC-NCM83)cathodes by the regulation of pre-lithiation *** well-balanced pre-lithiation kinetics have been proved to greatly improve the proportion of layered phase in the intermediate by inhibiting the formation of metastable spinel phase,which promoted the rapid transformation of the intermediate into highly-ordered layered SC-NCM83 in the subsequent lithiation *** coating a layer of li_(2)O–B_(2)O_(3),the resultant cathodes deliver superior cycling stability with 90.9%capacity retention at 1C after 300 cycles in pouch-type full *** enhancement mechanism has also been *** findings exhibit fundamental insights into the pre-lithiation kinetics process for guiding the synthesis of high-quality singlecrystalline Ni-rich cathodes.

关键词： Single-crystalline cathode Ni-rich oxides Pre-lithiation li-ion batteries Surface modification

Development of EPDM composites reinforced by CNTs@SiO_(2)for thermal protection systems of aerospace propulsion:Significant improvement in oxidation and ablation resistance properties

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第2期37卷 471-481页

作者： li WANG Jiang li Kang li Yiwei WANG Chenyang MA Science and Technology on Combustion Internal Flow and Thermal-Structure LaboratoryNorthwestern Polytechnical UniversityXi’an 710072China

Carbon Nanotubes(CNTs)reinforced Polymer-Matrix Composites(PMCs)is widely used as insulation materials in thermal protection system of aerospace ***,CNTs are prone to oxidation and have high thermal conductivities,which makes it difficult to improve the ablation resistance of insulation materials that contain ***_(2)was encapsulated onto the surface of CNTs(CNTs@SiO_(2)),which were then added to Ethylene Propylene Diene Monomer(EPDM)rubber to prepare the insulation *** analysis and ablation test were used to evaluate the resistance of the insulation materials to thermal oxidation and ***,scanning electron microscopy was performed to analyze their *** revealed that the addition of CNTs@SiO_(2)could visibly reduce the effects of hot corrosion and ablation on insulation *** C-CNTs@SiO_(2)-1 formulation had the best ablative ***,compared with the unencapsulated formulation(C-CNTs-10),the C-CNTs@SiO_(2)-1 formulation reduced the line ablation rate by 51%to 0.0130 mm/s after oxygen-acetylene ***,the ablation mechanism was investigated based on the effects of the CNTs@SiO_(2)additive on their ***,the improvement in ablation performance may be attributed to CNTs@SiO_(2)-induced decreases in thermal conductivity,improvement in the hot corrosion resistance in the char layer,and changes in the microstructure.

关键词： Polymer-Matrix Composites(PMCs) Carbon Nanotubes(CNTs) Thermal properties Ablation Oxidation

Multi-Physics Coupled Acoustic-Mechanics Analysis and Synergetic Optimization for a Twin-Fluid Atomization Nozzle

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第3期37卷 204-223页

作者： Wenying li Yanying li Yingjie Lu Jinhuan Xu Bo Chen li Zhang Yanbiao li College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310023China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China School of Materials Science and Engineering Northwestern Polytechnical UniversityXian 710072China Guizhou Anda Aviation Forging Co. Ltd.Anshun 561005China

Fine particulate matter produced during the rapid industrialization over the past decades can cause significant harm to human ***-fluid atomization technology is an effective means of controlling fine particulate matter *** this paper,the influences of the main parameters on the droplet size,effective atomization range and sound pressure level(SPL)of a twin-fluid nozzle(TFN)are investigated,and in order to improve the atomization performance,a multi-objective synergetic optimization algorithm is presented.A multi-physics coupled acousticmechanics model based on the discrete phase model(DPM),large eddy simulation(LES)model,and Ffowcs Williams-Hawkings(FW-H)model is established,and the numerical simulation results of the multi-physics coupled acoustic-mechanics method are verified via experimental *** on the analysis of the multi-physics coupled acoustic-mechanics numerical simulation results,the effects of the water flow on the characteristics of the atomization flow distribution were obtained.A multi-physics coupled acoustic-mechanics numerical simulation result was employed to establish an orthogonal test database,and a multi-objective synergetic optimization algorithm was adopted to optimize the key parameters of the *** optimal parameters are as follows:A gas flow of 0.94 m^(3)/h,water flow of 0.0237 m^(3)/h,orifice diameter of the self-excited vibrating cavity(SVC)of 1.19 mm,SVC orifice depth of 0.53 mm,distance between SVC and the outlet of nozzle of 5.11 mm,and a nozzle outlet diameter of 3.15 *** droplet particle size in the atomization flow field was significantly reduced,the spray distance improved by 71.56%,and the SPL data at each corresponding measurement point decreased by an average of 38.96%.The conclusions of this study offer a references for future TFN research.

关键词： Twin-fluid nozzle BP neural network Multi-objective optimization Multi-physics coupled Acousticmechanics analysis Genetic algorithm

基于RBF-PSO算法的潜艇尾部结构噪声优化

在线全文

学校读者我要写书评

暂无评论

噪声与振动控制 2024年第1期44卷 199-204页

作者：李舒成张冠军柯昱照武汉理工大学船海与能源动力工程学院武汉430063 武汉理工大学高性能船舶技术教育部重点实验室武汉430063

针对潜艇尾部结构噪声突出问题,选取潜艇尾部桨轴艇耦合模型为研究对象,以潜艇尾部质量为约束条件,以纵向、横向激励力下的水下潜艇尾部辐射声功率级为优化目标,设计以尾壳板厚度、T型材结构参数(面板宽、腹板高、面板厚度、腹板厚度)... 详细信息

针对潜艇尾部结构噪声突出问题,选取潜艇尾部桨轴艇耦合模型为研究对象,以潜艇尾部质量为约束条件,以纵向、横向激励力下的水下潜艇尾部辐射声功率级为优化目标,设计以尾壳板厚度、T型材结构参数(面板宽、腹板高、面板厚度、腹板厚度)为设计变量的均匀试验设计,采用径向基函数(Radia Basis Function,RBF)神经网络构建反映设计变量与优化目标之间映射关系的代理模型,使用粒子群算法(Particle Swarm Optimization,PSO)对潜艇尾部噪声进行多目标优化。研究表明:纵向激励下潜艇尾部水下辐射声功率合成级降低3.79 dB,横向激励下潜艇尾部水下辐射声功率合成级降低1.55 d B,潜艇尾部质量降低3.424 t。将RBF-PSO算法应用于潜艇尾部结构低频噪声优化问题效果较好,可以为潜艇的结构噪声优化提供指导。

关键词：声学 RBF神经网络粒子群算法潜艇尾部噪声优化

基于POA-VMD和MPE的光纤周界入侵信号降噪方法

在线全文

学校读者我要写书评

暂无评论

激光与光电子学进展 2024年第17期16卷 141-150页

作者：马愈昭朱庆啸吕其明李猛中国民航大学电子信息与自动化学院中国民航大学空中交通管理学院

针对当下的光纤周界入侵事件复杂多变以及噪声干扰的问题，需要对光纤周界系统采集的信号进行去噪处理。首先，提出了鹈鹕算法优化的变分模态分解降噪，并引入多尺度排列熵判决机制提高抑制模态混叠与虚假分量能力，最终将筛选出的信号... 详细信息

针对当下的光纤周界入侵事件复杂多变以及噪声干扰的问题，需要对光纤周界系统采集的信号进行去噪处理。首先，提出了鹈鹕算法优化的变分模态分解降噪，并引入多尺度排列熵判决机制提高抑制模态混叠与虚假分量能力，最终将筛选出的信号组成重构信号，实现整个信号的去噪。实验结果表明，在双Mach-Zehnder光纤周界传感系统判别入侵的过程中，信号去噪方面有了明显的改善，以去噪信噪比、相关系数、降噪后信号的均方根误差为降噪性能评价指标，本文所提方法与现有的集合经验模态分解-相关系数和互补集合经验模态分解-相关系数方法相比去噪信噪比有所降低，相关系数明显提高，去噪信号的均方根误差略有减少。该算法不仅能够更好地消除光纤周界系统采集信号的噪声，还最大程度地保留了信号的特征信息。

关键词：光纤传感鹈鹕优化算法变分模态分解多尺度排列熵

同方期刊数据库

APF-GAN:Exploring asymmetric pre-training and fine-tuning strategy for conditional generative adversarial network

在线全文

学校读者我要写书评

暂无评论

Computational Visual Media 2024年第1期10卷 187-192页

作者： Yuxuan li lingfeng Yang Xiang li College of Computer Science Nankai UniversityTianjinChina School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjingChina

The use of generative adversarial network(GAN)-based models for the conditional generation of image semantic segmentation has shown promising results in recent ***,there are still some limitations,including limited diversity of image style,distortion of detailed texture,unbalanced color tone,and lengthy training *** address these issues,we propose an asymmetric pre-training and fine-tuning(APF)-GAN model.

关键词： tuning network asymmetric

A Long-Time-Step-Permitting Tracer Transport Model on the Regular Latitude–Longitude Grid

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第3期41卷 493-508页

作者： Jianghao li li DONG Key Laboratory of Earth System Modeling and Prediction China Meteorological AdministrationBeijing 100081China State key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric Physics(IAP)Chinese Academy of SciencesBeijing 100029China State Key Laboratory of Severe Weather(LaSW) Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

If an explicit time scheme is used in a numerical model, the size of the integration time step is typically limited by the spatial resolution. This study develops a regular latitude–longitude grid-based global three-dimensional tracer transport model that is computationally stable at large time-step sizes. The tracer model employs a finite-volume flux-form semiLagrangian transport scheme in the horizontal and an adaptively implicit algorithm in the vertical. The horizontal and vertical solvers are coupled via a straightforward operator-splitting technique. Both the finite-volume scheme's onedimensional slope-limiter and the adaptively implicit vertical solver's first-order upwind scheme enforce monotonicity. The tracer model permits a large time-step size and is inherently conservative and monotonic. Idealized advection test cases demonstrate that the three-dimensional transport model performs very well in terms of accuracy, stability, and efficiency. It is possible to use this robust transport model in a global atmospheric dynamical core.

关键词： tracer transport numerical stability latitude–longitude grid

Crack propagation and damage evolution of metallic cylindrical shells under internal explosive loading

在线全文

学校读者我要写书评

暂无评论

DEFENCE TECHNOLOGY 2024年第9期39卷 133-146页

作者： Luo, Yusong li, Weibing li, Junbao li, Wenbin Wang, Xiaoming Nanjing Univ Sci & Technol ZNDY Ministerial Key Lab Nanjing 210094 Peoples R China

This paper investigates the three-dimensional crack propagation and damage evolution process of metallic column shells under internal explosive loading. The calibration of four typical failure parameters for 40CrMnSiB steel was conducted through experiments and subsequently applied to simulations. The numerical simulation results employing the four failure criteria were compared with the differences and similarities observed in freeze-recovery tests and ultra-high-speed tests. This analysis addressed the critical issue of determining failure criteria for the fracture of a metal shell under internal explosive loads. Building upon this foundation, the damage parameter Dc, linked to the cumulative crack density, was defined based on the evolution characteristics of a substantial number of cracks. The relationship between the damage parameter and crack velocity over time was established, and the influence of the internal central pressure on the damage parameter and crack velocity was investigated. Variations in the fracture modes were found under different failure criteria, with the principal strain failure criterion proving to be the most effective for simulating 3D crack propagation in a pure shear fracture mode. Through statistical analysis of the shell penetration fracture radius data, it was determined that the fracture radius remained essentially constant during the crack evolution process and could be considered a constant. The propagation velocity of axial cracks ranged between 5300 m/s and 12600 m/s, surpassing the Rayleigh wave velocity of the shell material and decreasing linearly with time. The increase in shell damage exhibited an initial rapid phase, followed by deceleration, demonstrating accelerated damage during the propagation stage of the blast wave and decelerated damage after the arrival of the rarefaction wave. This study provides an effective approach for investigating crack propagation and damage evolution. The derived crack propagation and damag

关键词： Internal explosive loading Failure criterion Crack propagation Damage evolution Freeze-recovery test INTERMEDIATE PHASE SHEAR-BAND STEEL FRAGMENTATION DEFORMATION MECHANISM