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亚临界区圆柱绕流相干结构壁面模化混合RANS/LES模型

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物理学报 2024年第5期73卷 190-216页

作者：季梦尤云祥韩盼盼邱小平马乔吴凯健上海交通大学海洋工程国家重点实验室上海200240 上海君昱信息科技有限公司上海201800 上海交通大学三亚崖州湾深海科技研究院三亚572000

本文发展了一种具有壁面模化大涡模拟能力的雷诺平均纳维-斯托克斯(RANS)和大涡模拟(LES)方法的混合模型(简称WM-HRL模型),致力于对亚临界区雷诺数钝体绕流相干结构这类复杂流动现象进行高置信度的CFD解析模拟研究.该方法通过一个仅与... 详细信息

本文发展了一种具有壁面模化大涡模拟能力的雷诺平均纳维-斯托克斯(RANS)和大涡模拟(LES)方法的混合模型(简称WM-HRL模型),致力于对亚临界区雷诺数钝体绕流相干结构这类复杂流动现象进行高置信度的CFD解析模拟研究.该方法通过一个仅与当地网格空间分布尺寸有关的湍动能解析度指标参数rk即可实现从RANS到LES的无缝快速转换,并且RANS/LES混合转换区的边界位置及其各个分区(包括RANS区、LES区及RANS/LES混合转换区)对湍动能的解析能力均可通过两个指标参数nrk1-Q和nrk2-Q准则进行预先设定.通过对雷诺数Re=3900下圆柱绕流场的系列数值模拟研究,获得了能够高置信度解析并捕捉其绕流场中三维时空瞬态发展相干结构特性的湍动能解析度指标参数nrk1-Q和nrk2-Q准则的组合条件.研究表明,该WM-HRL模型不仅能够准确获取圆柱绕流场中剪切层小尺度K-H不稳定性结构的精细谱结构,而且在同一套网格系统下通过变化湍动能解析度指标参数nrk2-Q和nrk1-Q准则的组合条件,还可以精细解析圆柱绕流场中两类不同回流区的长度结构特征,及其对应的圆柱尾部近壁面处V和U形两个平均流向速度剖面的分支结构特性.

关键词：圆柱绕流相干结构 Kelvin-Helmholtz不稳定性混合RANS/LES模型

Genetically modified non-human primate models for research on neurodegenerative diseases

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Zoological Research 2024年第2期45卷 263-274页

作者： Ming-Tian pan han Zhang Xiao-Jiang Li Xiang-Yu Guo Guangdong Key Laboratory of Non-human Primate Research Guangdong-Hongkong-Macao Institute of CNS RegenerationJinan UniversityGuangzhouGuangdong 510632China

Neurodegenerative diseases(NDs)are a group of debilitating neurological disorders that primarily affect elderly populations and include Alzheimer's disease(AD),Parkinson's disease(PD),Huntington's disease(HD),and amyotrophic lateral sclerosis(ALS).Currently,there are no therapies available that can delay,stop,or reverse the pathological progression of NDs in clinical settings.As the population ages,NDs are imposing a huge burden on public health systems and affected families.Animal models are important tools for preclinical investigations to understand disease pathogenesis and test potential treatments.While numerous rodent models of NDs have been developed to enhance our understanding of disease mechanisms,the limited success of translating findings from animal models to clinical practice suggests that there is still a need to bridge this translation gap.Old World nonhuman primates(NHPs),such as rhesus,cynomolgus,and vervet monkeys,are phylogenetically,physiologically,biochemically,and behaviorally most relevant to humans.This is particularly evident in the similarity of the structure and function of their central nervous systems,rendering such species uniquely valuable for neuroscience research.Recently,the development of several genetically modified NHP models of NDs has successfully recapitulated key pathologies and revealed novel mechanisms.This review focuses on the efficacy of NHPs in modeling NDs and the novel pathological insights gained,as well as the challenges associated with the generation of such models and the complexities involved in their subsequent analysis.

关键词： Neurodegeneration Non-human primate Macaque monkey Animal model Gene modification

Galerkin-based quasi-smooth manifold element(QSME)method for anisotropic heat conduction problems in composites with complex geometry

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 137-154页

作者： pan WANG Xiangcheng han Weibin WEN Baolin WANG Jun LIANG School of Civil Engineering Central South UniversityChangsha 410083China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China School of Science Harbin Institute of TechnologyShenzhen 518055Guangdong ProvinceChina

The accurate and efficient analysis of anisotropic heat conduction problems in complex composites is crucial for structural design and performance evaluation. Traditional numerical methods, such as the finite element method(FEM), often face a trade-off between calculation accuracy and efficiency. In this paper, we propose a quasi-smooth manifold element(QSME) method to address this challenge, and provide the accurate and efficient analysis of two-dimensional(2D) anisotropic heat conduction problems in composites with complex geometry. The QSME approach achieves high calculation precision by a high-order local approximation that ensures the first-order derivative continuity.The results demonstrate that the QSME method is robust and stable, offering both high accuracy and efficiency in the heat conduction analysis. With the same degrees of freedom(DOFs), the QSME method can achieve at least an order of magnitude higher calculation accuracy than the traditional FEM. Additionally, under the same level of calculation error, the QSME method requires 10 times fewer DOFs than the traditional FEM. The versatility of the proposed QSME method extends beyond anisotropic heat conduction problems in complex composites. The proposed QSME method can also be applied to other problems, including fluid flows, mechanical analyses, and other multi-field coupled problems, providing accurate and efficient numerical simulations.

关键词： anisotropic heat conduction quasi-smooth manifold element(QSME) composite with complex geometry numerical simulation finite element method(FEM)

Unstructured Road Extraction in UAV Images based on Lightweight Model

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 372-384页

作者： Di Zhang Qichao An Xiaoxue Feng Ronghua Liu Jun han Feng pan School of Automation Beijing Institute of TechnologyBeijing 100081China Tianjin Institute of Maritime Navigation Instruments Tianjin 300130China The 716th Research Institute of China Shipbuilding Group Co. LtdJiangsu 222061China

There is no unified planning standard for unstructured roads,and the morphological structures of these roads are complex and varied.It is important to maintain a balance between accuracy and speed for unstructured road extraction models.Unstructured road extraction algorithms based on deep learning have problems such as high model complexity,high computational cost,and the inability to adapt to current edge computing devices.Therefore,it is best to use lightweight network models.Considering the need for lightweight models and the characteristics of unstructured roads with different pattern shapes,such as blocks and strips,a TMB(Triple Multi-Block)feature extraction module is proposed,and the overall structure of the TMBNet network is described.The TMB module was compared with SS-nbt,Non-bottleneck-1D,and other modules via experiments.The feasibility and effectiveness of the TMB module design were proven through experiments and visualizations.The comparison experiment,using multiple convolution kernel categories,proved that the TMB module can improve the segmentation accuracy of the network.The comparison with different semantic segmentation networks demonstrates that the TMBNet network has advantages in terms of unstructured road extraction.

关键词： Unstructured road Lightweight model Triple Multi-Block(TMB) Semantic segmentation net

Compositional and Hollow Engineering of Silicon Carbide/Carbon Microspheres as High-Performance Microwave Absorbing Materials with Good Environmental Tolerance

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Nano-Micro Letters 2024年第9期16卷 128-146页

作者： Lixue Gai Yahui Wang pan Wan Shuping Yu Yongzheng Chen Xijiang han Ping Xu Yunchen Du MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001People’s Republic of China Anhui Provincial Laboratory of Advanced Laser Technology College of Electronic EngineeringNational University of Defense TechnologyHefei 230037People’s Republic of China

Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions,while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals.Herein,we have successfully implemented compositional and structural engineering to fabricate hollow SiC/C microspheres with controllable composition.The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites.The formation of hollow structure not only favors lightweight feature,but also generates considerable contribution to microwave attenuation capacity.With the synergistic effect of composition and structure,the optimized SiC/C composite exhibits excellent performance,whose the strongest reflection loss intensity and broadest effective absorption reach−60.8 dB and 5.1 GHz,respectively,and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies.In addition,the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.

关键词： SiC/C composites Compositional engineering Hollow engineering Microwave absorption Environmental tolerance

Influence of Micro/Nano-Ti Particles on the Corrosion Behavior of AZ31-Ti Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 484-498页

作者： Jinchao Jiao Jin Zhang Yong Lian Shengli han Kaihong Zheng Fusheng pan Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 10083China Beijing Key Laboratory for Corrosion Erosion and Surface Technology Beijing 100083China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 404100China

Adding Ti particles to magnesium alloy simultaneously enhances its strength and ductility.However,how these particles influence on Mg alloy’s corrosion performance is seldom reported.The corrosion behavior of AZ31-Ti composites containing titanium nanoparticles(1.5 and 5 wt%)and micron particles(10 wt%)prepared by powder metallurgical in 3.5 wt%NaCl solution was investigated.The results indicate that Ti particles serve as the primary location for the cathodic hydrogen reduction reaction,resulting in intense galvanic corrosion between the Ti and Mg matrix.Ti nanoparticles distributed at the interface of the original AZ31 powder were in a discontinuous mesh structure,thus failing to act as a barrier against corrosion.The corrosion products with the existence of numerous cracks gradually peel off during the corrosion process and cannot protect the matrix.The average corrosion rate P_(w) of AZ31,AZ31-1.5%Ti,AZ31-5%Ti,and AZ31-10%Ti after 7 days of immersion is 27.55,105.65,283.67,and 99.35 mm/y,respectively.Therefore,AZ31-Ti composites can be considered as potential candidates for degradable fracturing tools.Otherwise,it is recommended to improve their corrosion resistance through surface treatment.

关键词： AZ31-Ti composite Nano-Ti Micro-Ti Corrosion behavior Scanning Kelvin probe force microscopy(SKPFM)

Radiation build-up and dissipation in Raman random fiber laser

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Science China(Information Sciences) 2024年第1期67卷 254-260页

作者： Shengtao LIN Zinan WANG Jiaojiao ZhanG pan WANG han WU Yifei QI Key Laboratory of Optical Fiber Sensing and Communications University of Electronic Science and Technology of China College of Electronics and Information Engineering Sichuan University

Raman random fiber laser(RRFL) is a complex physical system that arises from the distributed Raman amplification and the intrinsic stochasticity of fiber scattering.The analysis of the underlying lightwave kinetics at steady state has been the focus of considerable interest.However,the transient state,such as the RRFL build-up and dissipation,is particularly important for revealing the lightwave interaction process.Here,we investigate for the first time the RRFL dynamics at the transient state and track the RRFL temporal and spectral evolution theoretically and experimentally.Particularly,with the contribution of random distributed feedback,RRFL build-up exhibits continuous Verhulst logistic growth curves without cavity-related features,which is significantly different from the step-like growth curve of conventional fiber lasers.Furthermore,the radiation build-up duration is inversely related to the pump power,and the spectral evolution of the RRFL undergoes two phases,i.e.,from spectral density increase to spectral broadening.From the steady state to the pump switch-off state,the RRFL output power dissipates immediately,and the remaining Stokes lightwave from the Rayleigh scattering will gradually disappear after one round trip.This work provides new insights into the transient dynamic features of the RRFL.

关键词： random fiber laser stimulated Raman scattering transient phenomenon nonlinear optics łinebreak biological growth dynamics

Effects of Acupotomy on Immobilization-Induced Gastrocnemius Contracture and Fibrosis in Rats via Wnt/β-Catenin Signaling

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Chinese Journal of Integrative Medicine 2024年第7期30卷 633-642页

作者： HU Rui pan Jun-kang LI Jia-hui ZhanG han LI Shao-rong ZhanG Yi School of Acupuncture-Moxibustion and Tuina Beijing University of Chinese Medicine Acupuncture Department Kunming Municipal Hospital of Traditional Chinese Medicine

Objective: To determine whether acupotomy ameliorates immobilization-induced muscle contracture and fibrosis via Wnt/β-catenin signaling pathway. Methods: Thirty Wistar rats were randomly divided into 5 groups(n=6) by a random number table, including control, immobilization, passive stretching, acupotomy, and acupotomy 3 weeks(3-w) groups. The rat model of gastrocnemius contracture was established by immobilizing the right hind limb in plantar flexion for 4 weeks. Rats in the passive stretching group received passive stretching at gastrocnemius, a daily series of 10 repetitions for 30 s each at 30-s intervals for 10 consecutive days. Rats in the acupotomy and acupotomy 3-w groups received acupotomy once and combined with passive stretching at gastrocnemius a daily series of 10 repetitions for 30 s each at 30-s intervals for 10 consecutive days. Additionally, rats in the acupotomy 3-w group were allowed to walk freely for 3 weeks after 10-day therapy. After treatment, range of motion(ROM), gait analysis [i.e., paw area, stance/swing and maximum ratio of paw area to paw area duration(Max dA/dT)], gastrocnemius wet weight and the ratio of muscle wet weight to body weight(MWW/BW) were tested. Gastrocnemius morphometric and muscle fiber cross-sectional area(CSA) were assessed by hematoxylin-eosin staining. Fibrosis-related mRNA expressions(i.e., Wnt 1, β-catenin, axin-2, α-smooth muscle actin, fibronectin, and types Ⅰ and Ⅲ collagen) were measured using real-time quantitative polymerase chain reactions. Wnt 1, β-catenin and fibronectin concentrations were measured by enzyme-linked immunosorbent assay. Types Ⅰ and Ⅲ collagen in the perimysium and endomysium were analyzed using immunofluorescence. Results: Compared with the control group, ROM, gait function, muscle weight, MWW/BW and CSA were significantly decreased in the immobilization group(all P <0.01), while protein levels of types Ⅰ and Ⅲ collagen, Wnt 1, β-catenin, fibronectin and mRNA levels of fibrosis-related genes were obviously increased(all P<0.01). Treatme

关键词： acupotomy immobilization muscle contracture muscle fibrosis Wnt/β-catenin signaling

Recent advances in bioinspired vision systems with curved imaging structures

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Rare Metals 2024年第4期43卷 1407-1434页

作者： Ze-Ping He Xun han Wen-Qiang Wu Zhang-Sheng Xu Cao-Feng pan CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro-Nano Energy and SensorBeijing Institute of Nanoenergy and NanosystemsChinese Academy of Sciences School of Nanoscience and Technology University of Chinese Academy of Sciences ZJU-hangzhou Global Scientific and Technological Innovation Center School of Micro-Nano ElectronicsZhejiang University Institute of Microscale Optoelectronics Shenzhen University

Limited by the planar imaging structure,the commercial camera needs to introduce additional optical elements to compensate for the curved focal plane to match the planar image sensor.This results in a complex and bulky structure.In contrast,biological eyes possess a simple and compact structure due to their curved imaging structure that can directly match with the curved focal plane.Inspired by the structures and functions of biological eyes,curved vision systems not only improve the image quality,but also offer a variety of advanced functions.Here,we review the recent advances in bioinspired vision systems with curved imaging structures.Specifically,we focus on their applications in implementing different functions of biological eyes,as well as the emerging curved neuromorphic imaging systems that incorporate bioinspired optical and neuromorphic processing technologies.In addition,the challenges and opportunities of bioinspired curved imaging systems are also discussed.

关键词： Bioinspired Curved vision system Compound eye Chambered eye Neuromorphic