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Single pair of charge-2 Dirac and charge-2Weyl phonons in GeO_(2)

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Chinese Physics B 2024年第10期33卷 141-145页

作者： Dong-Chang He Jia-Xi Liu Pei-Tao Liu Jiang-Xu Li Xing-Qiu Chen Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

The presence of a pair of Weyl and Dirac points(WP-DP)in topological semimetal states is intriguing and sought after due to the effects associated with chiral topological ***,identifying these states in real materials poses a significant *** this study,by means of first-principles calculations we predict the coexistence of charge-2 Dirac and charge-2 Weyl phonons at high-symmetry points within a noncentrosymmetric P4_(1)2_(1)2 space ***,we propose GeO_(2)as an ideal candidate for realizing these ***,we observe two distinct surface arcs that connect the Dirac and Weyl points across the entire Brillouin zone,which could facilitate their detection in future experimental *** study not only presents a tangible material for experimentalists to explore the topological properties of WP-DP states but also opens up new avenues in the quest for ideal platforms to study chiral particles.

关键词： ological phonon Weyl points Dirac points

Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

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Plasma Science and Technology 2024年第1期26卷 42-49页

作者：耿江海林果王平丁玉剑丁杨俞华 Department of Electric Power Engineering North China Electric Power UniversityBaoding 071003People’s Republic of China China Electric Power research institute Beijing 100192People’s Republic of China Xinjiang Electric Power Company research institute Urumchi 830000People’s Republic of China Shanxi Electric Power Company research institute Taiyuan 030001People’s Republic of China

Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude *** this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 *** experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical *** duration of the dark period and the critical charge of streamer-toleader transition were obtained at high *** on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader *** with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified *** the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

关键词： streamer-to-leader transition model high altitude streamer stem convective diffusion radial thermal expansion

Construction of Simple Modules over the Quantum Affine Space

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Algebra Colloquium 2024年第1期31卷 1-10页

作者： Snehashis Mukherjee Sanu Bera School of Mathematical Sciences Ramakrishna Mission Vivekananda Educational and research institute Belur Math HowrahWest Bengal 711202India

The coordinate ring O_(q)(K^(n))of quantum affine space is the K-algebra presented by generators x_(1),...,x_(n) and relations x_(i)x_(j)=q_(ij)a_(j)a_(i) for all i,*** construct simple O_(q)(K^(n))-modules in a more general setting where the parameters qij lie in a torsion subgroup of K^(*)and show that analogous results hold as in the uniparameter case.

关键词： simple module quantum affine space quantum torus polynomial identity algebra

Single-wall carbon nanotube fiber non-woven fabrics with a high electrothermal heating response

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Nano research 2024年第6期17卷 5621-5628页

作者： Xinyu Jiao Lele Xu Xinyang Sun Chao Shi Peng-Xiang Hou Chang Liu Hui-Ming Cheng Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Faculty of Materials Science and Engineering/institute of Technology for Carbon Neutrality Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Carbon nanotube(CNT)fibers have great promise for constructing multifunctional fabrics with high electrical conductivity,good electro-heating ability,excellent flexibility,and a low ***,the inter-fiber contacts in the fabric greatly reduce these advantages and limit their ***,a simple pressure-fusing method to fabricate single-wall CNT(SWCNT)fiber non-woven fabrics(NWFs)that are composed of interconnected SWCNT fibers with fused joints is reported,which have good flexibility,a low density of 0.46 g/cm^(3),a high electrical conductivity of 3.7×10^(5)S/m,and a record high specific electrical conductivity of 803(S·m^(2))/*** also showed excellent electrical heating ability,so that a temperature of~160℃was rapidly reached at a low voltage of 2 *** with their low density,the SWCNT fiber NWFs are promising for use as a heating unit for low temperature battery protection and de-icing applications.

关键词： carbon nanotube fiber nonwoven fabrics fusing electrothermal heating

Wear-resistant Ag-MAX phase 3D interpenetrating-phase composites:Processing,structure,and properties

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Nano research 2024年第2期17卷 806-819页

作者： Yu Guo Xi Xie Zengqian Liu Longchao Zhuo Jian Zhang Shaogang Wang Qiqiang Duan Qing Jia Dake Xu Weihai Xue Deli Duan Filippo Berto Zhefeng Zhang Rui Yang Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048China Electrobiomaterials institute Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)Northeastern UniversityShenyang 110819China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Chemical Engineering Materials and EnvironmentSapienza University of RomeRoma 00185Italy

Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic *** MAX(M is an early transition metal,A is an element from III or IV main groups,and X is carbon or/and nitrogen)phase ceramics display a unique combination of properties and may serve as an ideal reinforcement phase for electrical contact *** biological materials evolved in nature generally exhibit three-dimensional(3D)interpenetrating-phase architectures,which may offer useful inspiration for the architectural design of electrical contact ***,a series of bi-continuous Ag-Ti_(3)SiC_(2) MAX phase composites with high ceramic contents exceeding 50 vol.%and having micron-and ultrafine-scaled 3D interpenetrating-phase architectures,wherein both constituents were continuous and mutually interspersed,were exploited by pressureless infiltration of Ag melt into partially sintered Ti_(3)SiC_(2) *** mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural *** composites exhibited a good combination of properties with high hardness over 2.3 GPa,high flexural strength exceeding 530 MPa,decent fracture toughness over 10 MPa·m^(1/2),and good wear resistance with low wear rate at an order of 10^(-5)mm^(3)/(N·m),which were much superior compared to the counterparts made by powder metallurgy *** particular,the hardness,electrical conductivity,strength,and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron-to ultrafine-scales at equivalent ceramic *** good combination of properties along with the facile processing route makes the Ag-Ti_(3)SiC_(2)3D interpenetrating-phase composites appealing for electrical contact applicatio

关键词： three-dimensional(3D)interpenetrating-phase architecture Ag-MAX(M=early transition metal A=element from III or IV main groups and X=carbon or/and nitrogen)phase composites melt infiltration electrical contact materials mechanical

Discontinuity development patterns and the challenges for 3D discrete fracture network modeling on complicated exposed rock surfaces

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2154-2171页

作者： Wen Zhang Ming Wei Ying Zhang Tengyue Li Qing Wang Chen Cao Chun Zhu Zhengwei Li Zhenbang Nie Shuonan Wang Han Yin College of Construction Engineering Jilin UniversityChangchun130026China Liaoning nonferrous Geological Exploration and research institute Co. Shenyang110013China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China northeastern University Shenyang110819China

Natural slopes usually display complicated exposed rock surfaces that are characterized by complex and substantial terrain undulation and ubiquitous undesirable phenomena such as vegetation cover and *** study presents a systematic outcrop research of fracture pattern variations in a complicated rock slope,and the qualitative and quantitative study of the complex phenomena impact on threedimensional(3D)discrete fracture network(DFN)*** the studies of the outcrop fracture pattern have been so far focused on local variations,thus,we put forward a statistical analysis of global *** entire outcrop is partitioned into several subzones,and the subzone-scale variability of fracture geometric properties is analyzed(including the orientation,the density,and the trace length).The results reveal significant variations in fracture characteristics(such as the concentrative degree,the average orientation,the density,and the trace length)among different ***,the density of fracture sets,which is approximately parallel to the slope surface,exhibits a notably higher value compared to other fracture sets across all *** improve the accuracy of the DFN modeling,the effects of three common phenomena resulting from vegetation and rockfalls are qualitatively analyzed and the corresponding quantitative data processing solutions are ***,the 3D fracture geometric parameters are determined for different areas of the high-steep rock slope in terms of the subzone *** results show significant variations in the same set of 3D fracture parameters across different regions with density differing by up to tenfold and mean trace length exhibiting differences of 3e4 *** study results present precise geological structural information,improve modeling accuracy,and provide practical solutions for addressing complex outcrop issues.

关键词： Complicated exposed rock surfaces Discontinuity characteristic variation Three-dimensional discrete fracture network modeling Outcrop study Vegetation cover and rockfalls

Reducing the vacancies associated with ferroelectric polarization to promote photocatalytic overall water splitting

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Science China Chemistry 2024年第10期67卷 3258-3264页

作者： Haozhi Qi Yuyang Kang Jian-An Liu Lichang Yin Wenyu Zhang Shangyi Ma Jianhang Qiu Lingli Li Weijin Hu Lianzhou Wang Gang Liu institute of metal research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Nanomaterials Centre School of Chemical Engineering and Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandSt LuciaBrisbane QLD 4072Australia

Ferroelectric materials hold great promise in photocatalytic water splitting because their built-in electric field induced by the depolarization field can fulfill the separation of photogenerated ***,a number of intrinsic charged vacancy defects are simultaneously generated to screen the depolarized field for stabilizing the crystal structure,always resulting in severe recombination of photogenerated carriers and thus poor overall water splitting ***,we proposed a strategy to promote the separation and transport of photogenerated carriers of ferroelectric photocatalysts by adjusting the ferroelectric polarization and altering the coordination environment of elements to reduce the defect ***,we prepared a series of Ta-doped PbTiO_(3)with low Pb(V_(Pb))and O(V_(O))vacancy concentrations by reducing the polarization intensity and strengthening the Pb–O *** Ta-doped PbTiO_(3)shows efficient charge separation and greatly enhanced photocatalytic overall water splitting activity with the assistance of *** work highlights the importance of regulating ferroelectric polarization and vacancy defect concentration by the doping strategy in charge separation for photocatalytic water splitting.

关键词： PbTiO_(3) ferroelectric polarization vacancy defect element doping photocatalytic overall water splitting

Microstructure,elastic/mechanical and thermal properties of CrTaO_(4):A new thermal barrier material?

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Journal of Advanced Ceramics 2024年第3期13卷 373-387页

作者： Shuang Zhang Xiaohui Wang Chao Zhang Huimin Xiang Yingwei Li Cheng Fang Mingliang Li Hailong Wang Yanchun Zhou School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Civil Engineering Wuhan UniversityWuhan 430072China

CrTaO_(4)(or Cr_(0.5)Ta_(0.5)O_(2))has been unexpectedly found to play a decisive role in improving the oxidation resistance of Cr and Ta-containing refractory high-entropy alloys(RHEAs).This rarely encountered complex oxide can effectively prevent the outward diffusion of metal cations from the ***,the oxidation kinetics of CrTaO_(4)-forming RHEAs is comparable to that of the well-known oxidation resistant Cr_(2)O_(3)-and Al_(2)O_(3)-forming Ni-based ***,CrTaO_(4)has been ignored and its mechanical and thermal properties have yet to be *** fill this research gap and explore the untapped potential for its applications,here we report for the first time the microstructure,mechanical and thermal properties of CrTaO_(4)prepared by hot-press sintering of solid-state reaction synthesized *** the HAADF and ABF-STEM techniques,rutile crystal structure was confirmed and short range ordering was directly *** addition,segregation of Ta and Cr was ***,CrTaO_(4)exhibits elastic/mechanical properties similar to those of yttria stabilized zirconia(YSZ)with Young’s modulus,shear modulus,and bulk modulus of 268,107,and 181 GPa,respectively,and Vickers hardness,flexural strength,and fracture toughness of 12.2±0.44 GPa,142±14 MPa,and 1.87±0.074 MPa·m^(1/2).The analogous elastic/mechanical properties of CrTaO_(4)to those of YSZ has spurred inquiries to lucrative leverage it as a new thermal barrier *** measured melting point of CrTaO_(4)is 2103±20 *** anisotropic thermal expansion coefficients areα_(a)=(5.68±0.10)×10^(-6)K^(-1),α_(c)=(7.81±0.11)×10^(-6)K^(-1),with an average thermal expansion coefficient of(6.39±0.11)×10^(-6)K^(-1).The room temperature thermal conductivity of CrTaO_(4)is 1.31 W·m^(-1)·K^(-1)and declines to 0.66 W·m^(-1)·K^(-1)at 1473 K,which are lower than most of the currently well-known thermal barrier *** the perspective of matched thermal expansion coefficient,CrTaO_(4)per

关键词： microstructure synthesis thermal conductivity thermal expansion coefficient melting point CrTaO_(4) mechanical and thermal properties

On the Innovation,Design,Construction,and Experiments of OMEGA-Based SSPS Prototype:The Sun-Chasing Project

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Engineering 2024年第5期36卷 90-101页

作者： Baoyan Duan Yiqun Zhang Guangda Chen Ze Zhao Jianwei Mi Xun Li Lin Yang Xi Li research institute on Mechatronics Xidian UniversityXi’an 710071China research institute of Antenna Xidian UniversityXi’an 710071China

This study systematically introduces the development of the world’s first full-link and full-system ground demonstration and verification system for the OMEGA space solar power satellite(SSPS).First,the OMEGA 2.0 innovation design was ***,field-coupling theoretical models of sunlight concentration,photoelectric conversion,and transmitting antennas were established,and a systematic optimization design method was ***,a beam waveform optimization methodology considering both a high beam collection efficiency and a circular stepped beam shape was ***,a control strategy was developed to control the condenser pointing toward the sun while maintaining the transmitting antenna toward the ***,a high-efficiency heat radiator design method based on bionics and topology optimization was ***,a method for improving the rectenna array’s reception,rectification,and direct current(DC)power synthesis efficiencies is ***,high-precision measurement technology for high-accuracy beam-pointing control was ***,a smart mechanical structure was designed and ***,the developed SSPS ground demonstration and verification system has the capacity for sun tracking,a high concentration ratio,photoelectric conversion,microwave conversion and emission,microwave reception,and rectification,and thus satisfactory results were obtained.

关键词： OMEGA-SSPS Full-link and full-system Beam collection efficiency Circular stepped beam shape Smart structure Field coupling theoretical model `Beam pointing control