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Pressure-induced hydrogen-dominant high-temperature superconductors

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National Science Review 2024年第7期11卷 14-16页

作者： Ho-kwang Mao Shanghai Advanced research in Physical Sciences center for high Pressure Science and technology Advanced research

Recent studies of hydrogen-dominant（superhydride） materials have led to putative discoveries of near-room temperature superconductivity at high pressures. The idea started more than half-a-century ago as a by-product of the quest for metallic hydrogen for which a natural consequence of its very high Debye temperature and phonon frequency due to the very low mass of the hydrogen atoms would lead to a high superconducting critical temperature （Tc） in weak coupling Bardeen-Cooper-Schrieffer（BCS） expression.

关键词： HYDRIDE LANTHANUM

A novel method for determining the resistivity of compressed superconducting materials

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Matter and Radiation at Extremes 2024年第4期9卷 1-3页

作者： Liling Sun Qi Wu Shu Cai Yang Ding Ho-kwang Mao center for high Pressure Science and technology Advanced research Beijing 100094China Institute of Physics Chinese Academy of SciencesBeijing 100190China

The measurement of resistivity in a compressed material within a diamond anvil cell presents significant *** high-pressure exper-imental setup makes it difficult to directly measure the size changes induced by pressure in the three crystallographic directions of the *** this study,we introduce a novel and effective method that addresses these technical *** method is anticipated to offer a valuable foundation for high-pressure investigations on quantum materials,particularly those with anisotropic layered structures.

关键词： resistivity method foundation

Tuning mechanical and electrical performances of B_(4)C-TiB_(2)ceramics in a two-step spark plasma sintering process

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Journal of Advanced Ceramics 2024年第4期13卷 518-528页

作者： Jun Zhao Xingshuo Zhang Zongning Ma Dong Wang Xing Jin Songlin Ran Advanced Ceramics research center School of Materials Science and EngineeringAnhui University of TechnologyMaanshan 243002China Anhui Engineering research center for high Efficiency Intelligent Photovoltaic Module Chaohu UniversityHefei 238024China

B_(4)C–TiB_(2)is an advanced electrically conductive ceramic with excellent mechanical and electrical discharge machinable *** is challenging and rewarding to achieve highly conductive and hard B_(4)C–TiB_(2)composites at a minimum content of conductive TiB2 that has inferior hardness but double specific gravity of the B_(4)C matrix.A novel strategy was used to construct conductive networks in B_(4)C‒15 vol%TiB2 composite ceramics with B_(4)C,TiC,and amorphous B as raw materials by a two-step spark plasma sintering *** influences of particle size matching between B_(4)C and TiC on the conducting of the strategy and the microstructure were discussed based on the selective matrix grain growth *** mechanical and electrical properties were also systematically *** B_(4)C–15 vol%TiB2 composite ceramic prepared from 10.29µm B_(4)C and 0.05µm TiC powders exhibited a perfect three-dimensional interconnected conductive network with a maximum electrical conductivity of 4.25×10^(4)S/m,together with excellent mechanical properties including flexural strength,Vickers hardness,and fracture toughness of 691±58 MPa,30.30±0.61 GPa,and 5.75±0.32 MPa·m^(1/2),respectively,while the composite obtained from 3.12µm B_(4)C and 0.8µm TiC powders had the best mechanical properties including flexural strength,Vickers hardness,and fracture toughness of 827±35 MPa,32.01±0.51 GPa,and 6.45±0.22 MPa·m^(1/2),together with a decent electrical conductivity of 0.65×10^(4)S/m.

关键词： B_(4)C-TiB_(2) mechanical properties electrical conductivity conductive network

Microplastic and Heavy Metals Distributions in Urban Rivers Sediments,China

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Journal of Ocean University of China 2024年第4期23卷 1015-1025页

作者： SONG Dandan SHANG Yujun WANG Xiuli ZHUANG Yuwei GUO Hui BI Shuping HU Jianjun high and New technology research center of Henan Academy of Sciences Zhengzhou 450002China Henan Provincial Cartographic Institute Zhengzhou 450008China

This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in *** showed that the abundance of microplastics ranged from 2412±187.5 to 7638±1312items kg^(-1)dry sediment across different survey stations,with an average abundance at(4388±713)items kg^(-1)dry *** further categorization,it was found that transparent fragments were the primary color and type of microplastics *** potential ecological risk index(RI)of heavy metals in sediments suggested a low level of ecological risk within a majority of the urban rivers *** was identified as the main potential ecological risk factor in the sediments of the studied *** was a relatively good significant linear relationship between the RI of heavy metals and the abundance of microplastics,bolstering the linkage between these two environmental ***,the concentrations of heavy metals in microplastics were not dependent on their corresponding contents in *** fact,the concentration of Cu,Cd,and As in microplastics were higher than those in the *** finding confirmed that microplastics could serve as carriers of heavy metals and introduce potential risks to aquatic wildlife and human through the food chain.

关键词： microplastic heavy metals risk assessment river sediments

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Additive manufacturing of NiTi lightweight porous structures bio-mimicking coral skeleton with enhanced mechanical properties and shape memory functions

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Science China(Technological Sciences) 2024年第8期67卷 2461-2474页

作者： LIU Xin GU DongDong YUAN LuHao ZHANG Han SUN JianFeng CHEN WenXin WANG Jie SHI KeYu Jiangsu Provincial research center for Laser Additive Manufacturing of high-Performance Components College of Materials Science and TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China

Concerning the high demand for lightweight and multifunctional properties of engineering structures, the coral skeleton-inspired sheet-based(CSS) structure, which was a novel bio-mimicking coral skeleton wall-septa architecture with a unique ability to resist wave shocks was fabricated using NiTi alloy by laser powder bed fusion(LPBF) technology. The effects of laser energy density(LED) on surface morphologies, microstructures, phase transformation behavior, and mechanical properties of LPBFfabricated CSS structures were systematically investigated. The results indicated that the size deviation was predominantly governed by powder adhesion and step effect. NiTi CSS structures with LED of 71 J·mm~(-3)possessed superior compressive modulus(~400 MPa), ultimate strength(~13 MPa), and energy absorption efficiency(~69%). The compression fracture mechanism of the LPBF-fabricated NiTi CSS structures was revealed to be predominantly brittle fracture accompanied by ductile fracture. Furthermore, the Ni_4Ti_3 nanoprecipitates induced the precipitation strengthening effect, enabling better shape memory response at LED of 71 J·mm~(-3), with a recoverable strain of 3.63% and recovery ratio of 90.8%, after heating under a pre-strain of 4%. This study highlights the importance of a bionic design strategy for enhancing the mechanical properties of NiTi components and offers the possibility to tailor its functional properties.

关键词： bioinspired structures laser powder bed fusion NiTi shape memory alloy mechanical performance

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Satellite anomaly detection based on reconstruction discrepancy theory utilizing a new dual-branch reconstruction model

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Science China Technological Sciences 2024年第10期67卷 3294-3307页

作者： ZHAO HaoTian QIU Shi LIU Ming CAO XiBin research center of Satellite technology School of AstronauticsHarbin Institute of Technology

To enhance the accuracy of deep learning methods based on reconstruction discrepancy in satellite anomaly detection tasks, this study proposes a dual-branch reconstruction model(DBRM) and designs a comprehensive satellite anomaly detection framework around this model. Firstly, we introduce the temporal-channel mixer(TC-Mixer) module, which mainly comprises a self-attention layer for capturing long-range temporal dependencies in telemetry data, and two types of feed-forward networks(FFN) for extracting complex patterns in the temporal and channel dimension of telemetry data. This design endows the TC-Mixer module with robust capabilities for extracting complicated dependencies in telemetry data. Secondly, with the TC-Mixer module as the main component, we designed the DBRM. This model utilizes a shared latent representation layer, allowing the regeneration branch and forecasting branch of the DBRM to share most of the feature extraction network architecture. This approach significantly enhances the model's regression accuracy while reducing computational complexity. Thirdly, using the DBRM as the core network model, we devised a comprehensive satellite anomaly detection framework. This includes an anomaly criterion that considers the reconstruction discrepancy of both the regeneration and forecasting branches, the peak-over-threshold(POT) method for anomaly thresholding, and the MIC-based feature engineering method, etc. Finally, we conducted comparative experiments with several SOTA anomaly detection algorithms on two public and one private satellite anomaly detection datasets. The experimental results validate the effectiveness and superiority of our proposed method.

关键词： anomaly detection reconstruction discrepancy dual-branch reconstruction model (DBRM) satellite telemetry data time series

highly efficient 1D p-Te/2D n-Bi_(2)Te_(3) heterojunction self-driven broadband photodetector

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Nano research 2024年第3期17卷 1864-1874页

作者： Chenchen Zhao Dongbo Wang Jiamu Cao Zhi Zeng Bingke Zhang Jingwen Pan Donghao Liu Sihang Liu Shujie Jiao Tianyuan Chen Gang Liu Xuan Fang Liancheng Zhao Jinzhong Wang School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China School of Astronautics Harbin Institute of TechnologyHarbin 150001China center for high Pressure Science and technology Advanced research Shanghai 201203China State Key Laboratory of high Power Semiconductor Lasers Changchun University of Science and TechnologyChangchun 130022China

Broadband photodetectors with self-driven functions have attracted intensive scientific interest due to their low energy consumption and high optical ***,high-performance broadband self-driven photodetectors are still a significant challenge due to the complex fabrication processes,environmental toxicity,high production costs of traditional 3D semiconductor materials and sharply raised contact resistance,severe interfacial recombination of 2D materials and 2D/3D mixed dimension ***,1D p-Te/2D n-Bi_(2)Te_(3) heterojunctions are constructed by the simple and low-cost hydrothermal method.1D p-Te/2D n-Bi_(2)Te_(3) devices are applied in photoelectrochemical(PEC)photodetectors,with their high performance attributed to the good interfacial contacts reducing interface *** device demonstrated a broad wavelength range(365–850 nm)with an Iph/Idark as high as *** R_(i),D^(*),and external quantum efficiency(EQE)values of the device were as high as 12.07 mA/W,5.87×10^(10) Jones,and 41.05%,respectively,which were significantly better than the performance of the prepared Bi_(2)Te_(3) and Te devices.A comparison of the freshly fabricated device and the device after 30 days showed that 1D p-Te/2D n-Bi_(2)Te_(3) had excellent stability with only 18.08%decay of *** is anticipated that this work will provide new emerging material for future design and preparation of a high-performance self-driven broadband photodetector.

关键词： topological insulating states interfacial recombination self-driven 1D p-Te/2D n-Bi_(2)Te_(3) photodetector

An efficient stiffness analysis model based on shear deformation theory for flexible skin shear variable-sweep wing

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Chinese Journal of Aeronautics 2024年第10期37卷 445-458页

作者： Yue BAI Guang YANG Hong XIAO Hongwei GUO Rongqiang LIU Bei LIU State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China China Aerodynamics research and Development center Institute of High-Speed AerodynamicsMianyang 621000China

Fixed-wing aircraft cannot maintain optimal aerodynamic performance at different flight *** a type of morphing aircraft,the shear variable-sweep wing(SVSW)can dramatically improve its aerodynamic performance by altering its shape to adapt to various flight *** order to achieve smooth continuous shear deformation,SVSW’s skin adopts a flexible composite skin design instead of traditional aluminum alloy ***,this also brings about the non-linear difficulty in stiffness modeling and *** this research,a new SVSW design and efficient stiffness modeling method are *** on shear deformation theory,the flexible composite skin is equivalently modeled as diagonally arranged nonlinear springs,simulating the elastic force interaction between the skin and the *** shear loading tests of flexible composite skin,the accuracy of this flexible composite skin modeling method is *** SVSW stiffness model was established,and its accuracy was verified through static loading *** effects of root connection,sweep angles,and flexible composite skin on the SVSW stiffness are ***,considering three typical flight conditions of SVSW:low-speed flow(Ma=0.3,Re=5.8210^(6)),transonic flow(Ma=0.9,Re=3.4410^(6)),and supersonic flow(Ma=3,Re=7.5110^(6)),the stiffness characteristics of SVSW under flight conditions were *** calculated results guide the application of SVSW.

关键词： Shear variable-sweep wing(SVSW) Flexible composite skin Morphing mechanism Stiffness analysis Loading tests Structure

Numerical investigation on thermomechanical behavior of alumina–calcium hexaluminate refractories for purging plug

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Journal of Iron and Steel research International 2024年第2期31卷 389-400页

作者： Li-ping Pan Ya-wei Li Fang-guan Tan Yi-chen Chen Yang-fan Xu Zhu He Bao-kuan Li The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina National-Provincial Joint Engineering research center of high Temperature Materials and Lining technology Wuhan University of Science and TechnologyWuhan430081HubeiChina

Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ***–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining *** thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling *** with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically *** results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 *** thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,*** addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the ***,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.

关键词： Purging plug Thermomechanical damage Refractory Design of experiments method Stress