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Effects of Bionic Leading Edge on the Aerodynamic Performance of a Compressor Cascade at a Low Reynolds Number

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Journal of Thermal Science 2024年第4期33卷 1272-1285页

作者： xu Huafeng ZHAO Shengfeng WANG Mingyang YANG Chengwu Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing100049China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing100190China

To achieve high-performance compressor cascades at low Reynolds number(Re),it is important to organize the boundary layer transition and separation processes efficiently and *** this study,the airfoil is focused on at a 5%blade height at the root of the orthogonal blade in the downflow passage of the high-load booster *** bionics modeling design is carried out for the leading edge of the original blade cascade;the response characteristics of laminar transition and separation to blades with different leading edge shapes at low Reynolds numbers are studied by using large eddy simulations combined with Omega vortex *** findings of this study demonstrate that bionic leading edge modeling can significantly improve the aerodynamic performance of blades at low Reynolds *** blades effectively suppress the formation of separation bubbles at low Reynolds numbers and weaken or even eliminate large-scale flow separation at the trailing *** addition,the blades can weaken the vortex intensity on the blade surface,reduce the areas of high-velocity fluctuations,and minimize aerodynamic losses caused by turbulence *** results should serve as a valuable reference for the aerodynamic design and flow control of the high-load booster stage blade at low Re.

关键词： low Reynolds number booster stage bionic leading edge large eddy simulation

Fe-Zn alloy, a new biodegradable material capable of reducing RoS and inhibiting oxidative stress

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Regenerative Biomaterials 2024年第2期3卷 114-122页

作者： Shuaikang Yang Weiqiang Wang Yanan xu Yonghui Yuan Shengzhi Hao School of Materials Science and Engineering Dalian University of TechnologyDalian 116024PR China Clinical Research Center for Malignant Tumor of Liaoning Province Cancer Hospital of Dalian University of TechnologyShenyang 110042PR China

Fe-based biodegradable materials have attracted significant attention due to their exceptional mechanical properties and favorable ***,research on Fe-based materials mainly focuses on regulating the degradation ***,excessive release of Fe ions during material degrada-tion will induce the generation of reactive oxygen species(ROS),leading to oxidative stress and ***,the con-trol of RoS release and the improvement of biocompatibility for Fe-based materials are very *** this study,new Fe-Zn alloys were prepared by electrodeposition with the intention of using Zn as an antioxidant to reduce oxidative damage during alloy ***,the impact of three potential degra-dation ions(Fe^(2+),Fe^(3+),Zn^(2+))from the Fe-Zn alloy on human endothelial cell(EC)activity and migration ability was ***,cell adhesion,cell activity,ROs production and DNA damage were assessed at various locations surrounding the ***,the influence of different concentrations of Zn^(2+) in the medium on cell viability and ROS production was *** levels of ROS exhibited evident toxic effects on ECs and promoted DNA *** an antioxidant,Zn?+effectively reduced ROS production around Fe and improved the cell viability on its surface at a concentration of 0.04 mmol/*** findings demonstrate that Fe-Zn alloy can attenuate the ROS generated from Fe degradation therebyenhancingcytocompatibility.

关键词： biodegradable iron Fe-Zn alloys reactive oxygen species oxidative stress cytocompatibility

Learning to select the recombination operator for derivative-free optimization

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Science China Mathematics 2024年第6期67卷 1457-1480页

作者： Haotian Zhang Jianyong Sun Thomas Back Zongben xu School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an710049China Leiden Institute of Advanced Computer Science Leiden UniversityLeiden2333 CANetherlands

Extensive studies on selecting recombination operators adaptively,namely,adaptive operator selection(AOS),during the search process of an evolutionary algorithm(EA),have shown that AOS is promising for improving EA's performance.A variety of heuristic mechanisms for AOS have been proposed in recent decades,which usually contain two main components:the feature extraction and the policy *** feature extraction refers to as extracting relevant features from the information collected during the search *** policy setting means to set a strategy(or policy)on how to select an operator from a pool of operators based on the extracted *** components are designed by hand in existing studies,which may not be efficient for adapting optimization *** this paper,a generalized framework is proposed for learning the components of AOS for one of the main streams of EAs,namely,differential evolution(DE).In the framework,the feature extraction is parameterized as a deep neural network(DNN),while a Dirichlet distribution is considered to be the policy.A reinforcement learning method,named policy gradient,is used to train the *** case studies,the proposed framework is applied to two DEs including the classic DE and a recently-proposed DE,which result in two new algorithms named PG-DE and PG-MPEDE,*** on the Congress of Evolutionary Computation(CEC)2018 test suite show that the proposed new algorithms perform significantly better than their ***,we prove theoretically that the considered classic methods are the special cases of the proposed framework.

关键词： evolutionary algorithm differential evolution adaptive operator selection reinforcement learning deep learning

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Low-Rank Optimal Transport for Robust Domain Adaptation

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1667-1680页

作者： Bingrong xu Jianhua Yin Cheng Lian Yixin Su Zhigang Zeng IEEE the School of Automation Wuhan University of TechnologyWuhan 430070China Intelligent Transportation Systems Research Center Wuhan University of TechnologyWuhan 430063 Chongqing Research Institute Wuhan University of TechnologyChongqingChina the School of Artificial Intelligence and Automation Huazhong University of Science and TechnologyWuhan 430074 the Key Laboratory of Image Processing and Intelligent Control of Education Ministry of China Wuhan 430074China

When encountering the distribution shift between the source(training) and target(test) domains, domain adaptation attempts to adjust the classifiers to be capable of dealing with different domains. Previous domain adaptation research has achieved a lot of success both in theory and practice under the assumption that all the examples in the source domain are welllabeled and of high quality. However, the methods consistently lose robustness in noisy settings where data from the source domain have corrupted labels or features which is common in reality. Therefore, robust domain adaptation has been introduced to deal with such problems. In this paper, we attempt to solve two interrelated problems with robust domain adaptation:distribution shift across domains and sample noises of the source domain. To disentangle these challenges, an optimal transport approach with low-rank constraints is applied to guide the domain adaptation model training process to avoid noisy information influence. For the domain shift problem, the optimal transport mechanism can learn the joint data representations between the source and target domains using a measurement of discrepancy and preserve the discriminative information. The rank constraint on the transport matrix can help recover the corrupted subspace structures and eliminate the noise to some extent when dealing with corrupted source data. The solution to this relaxed and regularized optimal transport framework is a convex optimization problem that can be solved using the Augmented Lagrange Multiplier method, whose convergence can be mathematically proved. The effectiveness of the proposed method is evaluated through extensive experiments on both synthetic and real-world datasets.

关键词： Domain adaptation low-rank constraint noise corruption optimal transport

Sodium metals for single emitter strong coupling:Alternative plasmonic candidates beyond noble metals

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 106-117页

作者： Yi Zhang Shuying Chen Yuning Han Xiulai xu Lin Zhou National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresJiangsu Key Laboratory of Artificial Functional MaterialsCollege of Engineering and Applied SciencesNanjing UniversityNanjing 210008China School of Information and Electronic Engineering(Sussex Artificial Intelligence Institute) Zhejiang Gongshang UniversityHangzhou 310018China Department of Physics&Astronomy University College LondonLondon WC1E 6BTUK State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking UniversityBeijing 100871China

This work provides a theoretical investigation into the strong coupling between a single quantum emitter(QE)and the surface plasmons of sodium metals in two representative plasmonic systems,i.e.,the semi-infinite metal-dielectric interface and the metal nanoparticles(NPs)of monomer/dimer *** both configurations,sodium metals exhibit distinctly stronger coupling strength and lower optical loss in the optical region than their noble metal counterparts,demonstrating the ideal candidate characteristics for single-molecule-level strong couplings with distinctly facile operation *** results provide new insights into extreme light-matter interactions with potential applications in quantum information,optical sensors,quantum chemistry,etc.

关键词： sodium metals plasmonics single quantum emitter strong coupling pseudomode

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Effect of fore/aft-loaded rotor on compressor stability under inlet circumferential distortion

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Chinese Journal of Aeronautics 2024年第5期37卷 199-213页

作者： Dakun SUN Benhao GU Fangfei NING Dengke xu Xiaofeng SUN School of Energy and Power Engineering Beihang UniversityBeijing 102206China Research Institute of Aero-engine Beihang UniversityBeijing 102206China

A modified small perturbation stability prediction model for axial compressors with circumferential inlet distortions is established and applied to investigate the effect of fore/aft-loaded rotor on compressor stability under circumferentially distorted inlet *** inlet total pressure distribution downstream of the distortion screen is measured in experiments and employed for simulations which are implemented via time-space spectral *** stall inception prediction results via the stability model indicate that the compressor with aft-loaded rotor not only performs better in terms of stability under uniform inlet,but also maintains a larger stability margin under circumferentially distorted *** experiments for compressors with fore-loaded and aft-loaded rotor are respectively carried *** results validate the reliability of numerical simulations and the predicted conclusion that the aft-loaded rotor is beneficial for compressor ***,the ability of the developed theoretical model for compressor stability prediction under circumferential distortions is *** addition,dynamic pressure signals at rotor tip measured in experiments illustrate that the circumferential distortion has little effect on the compressor stall pattern.

关键词： Axial compressor stability Inlet distortion Blade loading Small perturbation Time-space spectral method

Polyethylenimine-modified graphene quantum dots promote endothelial cell proliferation

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Regenerative Biomaterials 2024年第2期3卷 137-146页

作者： Qirong xu Chen Li Xiangyan Meng Xinghong Duo Yakai Feng School of Chemistry and Chemical Engineering Qinghai University for NationalitiesXining 810007PR China Key Laboratory of National Ethnic Affairs Commission of Resource Chemistry and Ecological Environment Protection on Qinghai-Tibet Plateau Xining 810007PR China institute of Disaster and Emergency Medicine Tianjin UniversityTianjin 300072PR China School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350PR China Key Laboratory of Systems Bioengineering(Ministry of Education) Tianjin UniversityTianjin 300072PR China

Endothelial cell proliferation plays an important role in angiogenesis and treatment of related *** aim of this study was to evaluate the effect of polyethylenimine(PEI)-modified graphene quantum dots(GQDs)gene vectors on endothelial cell *** GQDs-cationic polymer gene vectors were synthesized by amidation reaction,and used to deliver pzNF580 gene to Human umbilical vein endothelial cells(HUVECs)for promoting their *** chemical modification of GQDs can ad-just gene vectors'surface properties and charge distribution,thereby enhancing their interaction with gene molecules,which could effectively compress the pZNF580 *** CCK-8 assay showed that the cell viability was higher than 80%at higher vector concentration(40μg/mL),demonstrating that the GQDs-cationic polymer gene vectors and their gene complex nanoparticles(NPs)having low *** results of the live/dead cell double staining assay were consistent with those of the CCK-8 assay,in which the cell viability of the A-GQDs/pZNF580(94.38±6.39%),C-GQDs-PEI-polylactic acid-co-polyacetic acid(PLGA)/pZNF580(98.65±6.60%)and N-GQDs-PEI-PLGA/pZNF580(90.08±1.60%)groups was significantly higher than that of the Lipofectamine 2000/pzNF580(71.98±3.53%)positive treatment *** results of transfection and western blot experiments showed that the vector significantly enhanced the delivery of plasmid to HUVECs and increased the expression of pZNF580 in *** addition,the gene NPs better promote endothelial cell migration and *** cell migration rate and proliferation ability of C-GQDs-PEI-PLGA/pZNF580 and N-GQDs-PEI-PLGA/pZNF580 treatment groupS were higher than those of Lipofectamine 2000/pDNA treatment *** GQDs possess the potential to serve as efficient gene *** tightly bind gene molecules through charge and other non-covalent interactions,significantly improving the effciency of gene delivery and ensuring the smooth release of genes with

关键词： graphene quantum dots polyethylenimine ZNF580 gene endothelial cell proliferation

Sulfur vacancies and heterogeneous interfaces promote high performance sodium storage of bimetallic chalcogenide hollow nanospheres

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Journal of Energy Chemistry 2024年第8期95卷 596-610,I0013页

作者： Shiyue Cao Xiaoting xu Qiming Liu Huijuan Zhu Ting Hu Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education School of Physics and TechnologyWuhan UniversityWuhan 430072HubeiChina

Transition metal sulfides have high theoretical capacities and are considered as potential anode materials for sodium-ion ***,due to low inherent conductivity and significant volume expansion,the electrochemical performance is greatly *** this study,a nickel/manganese sulfide material(Ni_(0.96)S_(x)/MnS_(y)-NC)with adjustable sulfur vacancies and heterogeneous hollow spheres was prepared using a simple *** introduction of a concentration-adjustable sulfur vacancy enables the generation of a heterogeneous interface between bimetallic sulfide and sulfur *** interface collectively creates an internal electric field,improving the mobility of electrons and ions,increasing the number of electrochemically active sites,and further optimizing the performance of Na~+*** direction of electron flow is confirmed by Density functional theory(DFT)*** hollow nano-spherical material provides a buffer for expansion,facilitating rapid transfer *** innovative discovery involves the interaction between the ether-based electrolyte and copper foil,leading to the formation of Cu_9S_5,which grafts the active material and copper current collector,reinforcing mechanical *** results in a new heterostructure of Cu_9S_5 with Ni_(0.96)S_(x)/MnS_(y),contributing to the stabilization of structural integrity for long-cycle ***,Ni_(0.96)S_(x)/MnS_(y)-NC exhibits excellent electrochemical properties following our modification *** stability performance,Ni0_(.96)S_(x)/MnS_(y)-NC demonstrates an average decay rate of 0.00944%after 10,000 cycles at an extremely high current density of 10000 mA g^(-1),A full cell with a high capacity of 304.2 mA h g^(-1)was also successfully assembled by using Na_(3)V_(2)(PO_(4))_(3)/C as the *** study explores a novel strategy for interface/vacancy co-modification in the fabrication of high-performance sodium-ion batteries electrode.

关键词： Sulfur vacancies Heterogeneous interface Interactions Sodium ion batteries

Spatiotemporal variation of rainy season span and precipitation recorded by lacustrine laminated pollen in the Tibetan Plateau during the past two millennia

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Science China Earth Sciences 2024年第3期67卷 789-801页

作者： Anning CUI Houyuan LU Juzhi HOU Xingqi LIU Deke xu Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Group of Alpine Paleoecology and Human Adaptation State Key Laboratory of Tibetan Plateau Earth SystemResources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Capital Normal University College of Resource Environment and Tourism Beijing 100048China

The quantitative reconstruction of the length of the rainy season and precipitation on the Tibetan Plateau(TP) is crucial for revealing the spatiotemporal evolution of the Westerlies and Asian summer monsoon, as well as its ecological and environmental effects. Accurately determining the start and end times of the rainy season on the Plateau remains *** study determined the start and end times of the rainy season in different locations on the Plateau by identifying precipitation inflection points. We calculated the duration and precipitation amount of the rainy season and established a transfer function between the modern pollen assemblages and them. Then, we reconstructed the rainy season variations in Kusai Lake(northern TP) and Jiang Co(central TP) during the past two millennia. The results showed that, the rainy season precipitation in Kusai Lake recorded five periods of high precipitation: AD 580–680, 1000–1100, 1200–1450, 1550–1780, and 1920–present, corresponding to the stages with long rainy season. The rainy season precipitation sequence in Jiang Co recorded four periods of high precipitation: AD 80–500, 800–950, 1250–1450, and 1780–present, which is consistent with the long rainy season before AD 1000 but unclear afterward. Spatially, rainy season precipitation on the Plateau exhibited four patterns: “wet in both north and south” may be related to abnormally strong summer monsoons;“dry in both north and south” likely associated with weak Westerly wind and weak summer monsoon;“wet in the south and dry in the north” linked to strong summer monsoon and weak Westerly wind;and “dry in the south and wet in the north” connected to weak summer monsoon and strong Westerly wind. This study revealed the spatiotemporal evolution pattern of the rainy season onset and end, duration, and precipitation amount on the Plateau over the past two millennia. It provides natural background support for further understanding the coupling between Westerly wind and Asia

关键词： Tibetan Plateau Past two millennia Rainy season length Rainy season precipitation Quantitative reconstruction