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Flower-like CuS/γ-Fe_(2)O_(3) van der Waals heterostructures with highefficient electromagnetic wave absorption

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nano Research 2024年第4期17卷 3324-3333页

作者： na Lu Jingshen Xu Mengwei Yuan Genban Sun Beijing Key Laboratory of Energy Conversion and Storage materials Institution College of ChemistryBeijing Normal UniversityBeijing 100875China Center for Advanced materials Research Beijing Normal UniversityZhuhai 519087China

The escalating electromagnetic(EM)pollution issues and the demand to elevate military stealth technology make it imperative to develop cost-effective and high-performance electromagnetic wave(EMW)absorbing *** this paper,the flower-like CuS/γ-Fe_(2)O_(3) van der Waals(vdW)heterostructures have been synthesized via a facile two-step solvothermal *** flower-like CuS skeleton increases the attenuation path of EMW while reducing the material *** contents ofγ-Fe_(2)O_(3) nanoparticles anchor between the flower-like CuS nanosheets to constitute a heterogeneous structure,which enables dielectric and magnetic loss synergistically to optimize impedance matching and remarkably improve the EMW absorption *** minimum reflection loss(RLmin)is-49.36 dB with a thickness of only 1.6 mm and the effective absorption bandwidth(EAB)reaches 4.64 GHz(13.36–18 GHz).By adjusting the thickness of the absorber,the EAB can cover 96%of the GHz ***,the superior absorption of-61.53 dB at middle frequency band can be obtained by adjusting the amount of Fe_(2)O_(3) *** this study,the adjustment of EM parameters and the optimization of impedance matching have been achieved by constructing a novel vdW heterogeneous structure,which provides fresh ideas and references for the design of high-performance EMW absorbing materials.

关键词： flower-like CuS γ-Fe_(2)O_(3) van der Waals heterostructures impedance matching electromagnetic wave absorption

Microstructure and room temperature fracture toughness of Nb-Si-based alloys with Sr addition

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Rare Metals 2024年第8期43卷 3904-3912页

作者： Yong-Lin Huang Li-na Jia Bin Kong Yue-Ling Guo na Wang School of materials Science and Engineering Beihang UniversityBeijing 100191China

Nb-Si-based alloys show great potential to surpass the widely used Ni-based *** element Sr is widely applied in aluminum and magnesium alloys,but reports about the effects of Sr on Nb-Si-based alloys are quite ***,Nb-Si-based alloys with nominal compositions of Nb-15Si-24Ti-4Cr-2Al-2Hf-0/0.05/0.15Sr(at%)were prepared by directional solidification and heat *** microstructural characterization and room temperature fracture toughness of Nb-Si-based alloy were systematically *** show that all these alloys consist of Nb_5Si_3 phase embedded within Nb solid solution(Nb_(ss)) *** Nb_(5)Si_(3) phase becomes refined and more discontinuous after adding minor *** for the fracture toughness,0.05 at% and 0.15 at% Sr additions do not cause significant *** discontinuous and refining mechanism of Sr element was studied,and the analysis of toughness decreasing with Sr addition reveals that the size of Nb_(ss) phase plays a crucial role in determining the fracture toughness.

关键词： Nb-Si alloy Refinement Discontinuous Fracture toughness Nb_(ss)

Scattering-based hybrid network for facial attribute classification

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Frontiers of Computer Science 2024年第3期18卷 105-116页

作者： na LIU Fan ZHANG Liang CHANG Fuqing DUAN School of Artificial Intelligence Beijing Normal UniversityBeijing 100875China

Face attribute classification(FAC)is a high-profile problem in biometric verification and face *** recent research has been devoted to extracting more delicate image attribute features and exploiting the inter-attribute correlations,significant challenges still *** scattering transform(WST)is a promising non-learned feature *** has been shown to yield more discriminative representations and outperforms the learned representations in certain *** to the image classification task,WST can enhance subtle image texture information and create local deformation *** paper designs a scattering-based hybrid block,to incorporate frequency-domain(WST)and image-domain features in a channel attention manner(Squeezeand-Excitation,SE),termed WS-SE *** with CNN,WS-SE achieves a more efficient FAC performance and compensates for the model sensitivity of the small-scale affine *** addition,to further exploit the relationships among the attribute labels,we propose a learning strategy from a causal *** cause attributes defined using the causalityrelated information can be utilized to infer the effect attributes with a high confidence *** analysis experiments demonstrate the effectiveness of our model,and our hybrid model obtains state-of-the-art results in two public datasets.

关键词： wavelet scattering transform causality-related learning facial attribute classification

Fixed-Time Sliding Mode Control With Varying Exponent Coefficient for Modular Reconfigurable Flight Arrays

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 514-528页

作者： Jianquan Yang Chunxi Yang Xiufeng Zhang Jing na Faculty of Mechanical and Electrical Engineering Kunming University of Science and TechnologyKunming 650500 Yunnan International Joint Laboratory of Intelligent Control and Aoolication of Advanced Equipment Kunming 650500China IEEE

The modular system can change its physical structure by self-assembly and self-disassembly between modules to dynamically adapt to task and environmental requirements. Recognizing the adaptive capability of modular systems, we introduce a modular reconfigurable flight array(MRFA) to pursue a multifunction aircraft fitting for diverse tasks and requirements,and investigate the attitude control and the control allocation problem by using the modular reconfigurable flight array as a platform. First, considering the variable and irregular topological configuration of the modular array, a center-of-mass-independent flight array dynamics model is proposed to allow control allocation under over-actuated situations. Secondly, in order to meet the stable, fast and accurate attitude tracking performance of the MRFA, a fixed-time convergent sliding mode controller with state-dependent variable exponent coefficients is proposed to ensure fast convergence rate both away from and near the system equilibrium point without encountering the singularity. It is shown that the controller also has fixed-time convergent characteristics even in the presence of external disturbances. Finally,simulation results are provided to demonstrate the effectiveness of the proposed modeling and control strategies.

关键词： Control allocation dynamic model fixed-time stabilization modular reconfigurable flight array(MRFA) sliding mode

Overcoming the na-ion conductivity bottleneck for the cost-competitive chloride solid electrolytes

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Journal of Energy Chemistry 2024年第8期95卷 1-8,I0001页

作者： Lv Hu Hui Li Fang Chen Yating Liu Jinzhu Wang Cheng ma Hefei national Research Center for Physical Sciences at the Microscale CAS Key Laboratory of Materials for Energy ConversionDepartment of Materials Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026AnhuiChina national Synchrotron Radiation Laboratory Hefei 230026AnhuiChina

Chloride solid electrolytes possess multiple advantages for the construction of safe,energy-dense allsolid-state sodium batteries,but presently the chlorides with sufficiently high cost-competitiveness for commercialization almost all exhibit low na-ion conductivities of around 10^(-5)S cm^(-1)or ***,we report a chloride solid electrolyte,na_(2.7)ZFCl_(5.3)O_(0.7),which reaches a.na.ion conductivity of 2.29×10^(-4)S cm^(-1)at 25℃without involving overly expensive raw materials such as rare-earth chlorides or na_(2)*** addition to the efficient ion transport,na_(2.7)ZrCl_(5.3)O_(0.7)also shows an excellent deformability surpassing that of the widely studied na_(3)PS_(4),na_(3)SbS_(4),and na_(2)ZrCl_(6)solid *** combination of these advantages allows the all-solid-state cell based on na_(2.7)ZrCl_(5.3)O_(0.7)and naCrO_(2)to realize stable room-temperature cycling at a much higher specific current than those based on other non-viscoelastic chloride solid electrolytes in literature(120 ma g^(-1)vs.12-55 ma g^(-1));after 100 cycles at such a high rate,the na_(2.7)ZFCl_(5.3)O_(0.7)-based cell can still deliver a discharge capacity of 80 mah g^(-1)at25℃.

关键词： All-solid-state sodium batteries Ionic conductivities Solid electrolytes Chlorides High voltage stability

Research Progress on Myocardial Protection Strategies

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Expert Review of Chinese Medical

Expert Review of Chinese Medical 2024年第1期2卷 10-14页

作者： na An ma Li Xiatian Zhao Medical Department of Qingdao University

Myocaridial protection aims to salvage myocardium from ischemia and reperfusion injury and to reduce infarct size and its *** more than 30 years of development,the concept of ischemic preconditioning has evolved into"ischemic conditioning",a term that encompasses a number of related endogenous cardioprotective strategies,which can be applied either directly to the heart(ischemic preconditioning or postconditioning)or from afar,for example to a limb(remote ischemic preconditioning,preconditioning,or postconditioning).A variety of cardioprotective therapies have shown promising results in reducing infarct size and improving clinical outcomes in patients with ischemic heart disease.

关键词： ischemia/reperfusion injury myocaridial protection myocardial infarction research progress

High-current pulsed electron beam modification on microstructure and performance of Cu/CuW diffusion bonding joints

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Rare Metals 2024年第6期43卷 2819-2831页

作者： Na.na.Tian Cong-Lin Zhang Peng Lyu Jin-Tong Guan Jie Cai Qing-Feng Guan Shun Guo School of materials Science and Engineering Jiangsu UniversityZhenjiang 212013China School of material Science and Engineering Yancheng Institute of TechnologyYancheng 221051China Engineering Institute of Advanced manufacturing and Modern Equipment Technology Jiangsu UniversityZhenjiang 212013China

This study investigates the influence of high-current pulsed electron beam(HCPEB)modification on the microstructure and shear strength of Cu/CuW *** solid-state diffusion bonding of modified-Cu(MCu)and modified-CuW(M-CuW)was achieved by HCPEB modification pretreatment at a temperature of 800-900℃and a pressure of 5 MPa for 10-50 *** demonstrate that HCPEB modification facilitates the dissolution of W and Cu,resulting in the formation of a Cu_(0.4)W_(0.6)solid solution and thus enhancing the uniform distribution of ***,HCPEB-induced defects play a beneficial role in promoting the diffusion process by providing fast diffusion paths for *** optimal joints with the maximum shear strength of 213.7 MPa were obtained through bonding M-Cu and M-CuW at 900℃and 5 MPa for 30 min,which attributes to the combined effects of fine-grained strengthening and solid solution ***,the application of HCPEB modification showcases its effectiveness in promoting element diffusion and enhancing the mechanical performance of the joints.

关键词： HCPEB Element diffusion Shear strength Crystal defects Surface modification

Preparation of yttrium oxide coating with enhanced thermal shock resistance on refractories used for titanium alloy melting and casting

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Journal of Iron and Steel Research International 2024年第6期31卷 1411-1422页

作者： Ao Chen Yan ma Zhou-fu Wang Hao Liu Xi-tang Wang Sen-na Chen Chen-xin Zhang Zi-yi Tang Wei-dong Fu Wei Cheng The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Xiangyang Juli High Technology material Co. Ltd.Xiangyang 441705HubeiChina Xiangyang Public Inspection and Testing Center Xiangyang 441000HubeiChina

In order to enhance the service life of refractories for melting and casting of titanium alloy,preparation of yttrium oxide coatings on the refractories surface is an effective *** improvement of thermal shock stability of the coating is beneficial to its spalling resistance during the high-temperature service,and the available slurry with good performance is the *** effects of the varieties and contents of dispersant(sodium tripolyphosphate,sodium hexametaphosphate,sodium pyrophosphate,citric acid and polycarboxylate ammonium salt)and binder(aluminum dihydrogen phosphate,zirconium acetate and yttria sol)on the stability,rheological and thixotropic properties of yttrium oxide waterbased slurry were investigated,and the effects of slurry composition design on the thermal shock resistance of the coating were *** results showed that the introduction of polycarboxylate ammonium salt as dispersant significantly improved the stability of the slurry,and the varieties of the binders had significant effects on the dispersibility of the *** aluminum dihydrogen phosphate and polycarboxylate ammonium salt were used as binder and dispersant,respectively,the slurry had better stability,suitable rheological and thixotropic *** using aluminum dihydrogen phosphate as binder,the coating had good thermal shock resistance and no obvious cracks were observed for the coating after thermal shock,which was attributed to the yttrium aluminate binding phase generated in the *** effective method was provided for preparing yttrium oxide coatings with enhanced thermal shock resistance applied in the process of titanium alloy melting and casting.

关键词： Yttrium oxide-Slurry Stability Rheological property Thixotropic property-Coating Thermal shock resistance

Dynamic Response Impact of Vehicle Braking on Simply Supported Beam Bridges with Corrugated Steel Webs Based on Vehicle-Bridge Coupled Vibration Analysis

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 3467-3493页

作者： Yan Wang Siwen Li na Wei School of Civil Engineering Zhengzhou UniversityZhengzhou450001China

A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle *** modeling and solution of bridge vibrations induced by vehicle deceleration are realized using this *** method’s validity and reliability are substantiated through numerical examples.A simply supported beam bridge with a corrugated steel web is taken as an example and the effects of parameters such as the initial vehicle speed,braking acceleration,braking location,and road surface roughness on the mid-span displacement and impact factor of the bridge are *** results show that vehicle braking significantly amplifies mid-span displacement and impact factor responses in comparison to uniform vehicular motion across the ***,the influence of wheelto-bridge friction forces is of particular significance and cannot be *** the vehicle initiates braking near the middle of the span,both the mid-span displacement and impact factor of the bridge exhibit substantial increases,further escalating with higher braking *** favorable road surface conditions,the midspan displacement and the impact factor during vehicle braking may exceed the design values stipulated by *** is important to note that road surface roughness exerts a more pronounced effect on the impact factor of the bridge in comparison to the effects of vehicle braking.

关键词： Corrugated steel web girder bridges simply supported beam bridges vehicle-bridge coupled vibration braking impact factor