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Weakly Approximate Diagonalization of Homomorphisms into Finite von Neumann Algebras

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Acta Mathematica Sinica,English Series 2024年第9期40卷 2187-2194页

作者： Wen hua QIAN Jun Hao SHEN Wen Ming WU School of Mathematical Sciences Chongqing Normal UniversityChongqing 401331P.R.China Department of Mathematics and Statistics University of New HampshireDurhamNH 03824USA

Let A be a unital C^(∗)-algebra and B a unital C^(∗)-algebra with a faithful traceτ.Let n be a positive *** give the definition of weakly approximate diagonalization(with respect toτ)of a unital homomorphismφ:A→Mn(B).We give an equivalent characterization of McDuff Ⅱ_(1) *** show that,if A is a unital nuclear C^(∗)-algebra and B is a type Ⅱ_(1) factor with faithful traceτ,then every unital^(∗)-homomorphism φ:A→M_(n)(B)is weakly approximately *** B is a unital simple infinite dimensional separable nuclear C^(∗)-algebra,then any finitely many elements in Mn(B)can be simultaneously weakly approximately diagonalized while the elements in the diagonals can be required to be the same.

关键词： Weakly approximately diagonalizable McDuff factors nuclear hyperfinite

Atomistic study of inverse size effect induced by interfacial plasticity in pearlitic multi-principal element alloy

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Rare Metals 2024年第7期43卷 3341-3355页

作者： Chen Yang Qiao-Sheng Xia Cun-Hong Yin Dong-Peng hua College of Mechanical Engineering Guizhou UniversityGuiyang 550025China Key Laboratory of Advanced Manufacturing Technology Ministry of EducationGuizhou UniversityGuiyang 550025China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi'an 710072China

Owing to the fine nano-laminated structure,the pearlitic multi-principal element alloy(PMPEA) exhibits excellent mechanical and tribological ***,the incomplete understanding of the size effect of its lamella thickness and the unclear understanding of the plasticity-interface interaction mechanism limit further optimization of *** this study,the FeCoNi/Ni_3Ti interface-mediated plastic deformation behavior in PMPEA and the variation of mechanical and tribological properties with lamella thickness within the nanoscale range using molecular dynamics(MD) simulation were *** results indicate that the mechanical and tribological properties of the PMPEA with lamella thicknesses below 10 nm have a significant inverse size effect,i.e.,the smaller the lamella thickness,the weaker the *** is because the plastic carrier-interface interaction mechanism changes from a strengthening mechanism that hinders dislocations to a weakening mechanism that promotes dislocations with the decreases in the lamella thickness,and the weakening effect becomes more pronounced as the lamella thickness decreases and the number of interfaces *** particular,the deformation behavior of Ni_3Ti lamellae changes from crystal-like to amorphous-like with decreasing ***,in the sample with larger lamella thickness,the occurrence of hierarchical slips in the body-centered cubic(BCC) phase due to the multiprincipal elements effect can better alleviate the stress concentration caused by the dislocation accumulation at the interface,so that the phase interface exhibits outstanding load-bearing *** the dislocation pattern in BCC phase shows a firm high-density cell,which makes the substrate exhibit a stable tribological response.

关键词： Multi-principal element alloy Nano-laminated structure Molecular dynamics simulation Nanoindentation and nanoscratch

Escape probability for isotropic emitters near Kerr black hole with astrometric

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Communications in Theoretical Physics 2024年第5期76卷 128-133页

作者： Yu-Xuan Han Qing-hua Zhu Qing-Guo huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesNo.19A Yuquan RoadBeijing 100049China Department of Physics Chongqing UniversityChongqing 401331China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study UCASHangzhou 310024China

The paper investigates the escape probability for isotropic emitters near a Kerr black *** propose a new approach to obtain the escape probability in a general manner,going beyond previous case-by-case *** approach is based on studies of the black hole shadow with astrometric observable and can be applied to emitters with an arbitrary 4-velocities and locations,even to the emitters outside of the equatorial *** also consider representative examples illustrating how escape probabilities vary with distance,velocity,and inclination ***,this new approach provides an effective method for studying escape probabilities near Kerr black holes.

关键词： Kerr black hole photon escape probability isotropic emitters

Neutron irradiation influence on high-power thyristor device under fusion environment

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Nuclear Science and Techniques 2024年第4期35卷 65-81页

作者： Wei Tong hua Li Meng Xu Zhi-Quan Song Bo Chen School of Electrical Engineering and Automation Hefei University of TechnologyHefei 230009China Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

Because of their economy and applicability,high-power thyristor devices are widely used in the power supply systems for large fusion *** high-dose neutrons produced by deuterium–tritium(D–T)fusion reactions are irradiated on a thyristor device for a long time,the electrical characteristics of the device change,which may eventually cause irreversible *** this study,with the thyristor switch of the commutation circuit in the quench protection system(QPS)of a fusion device as the study object,the relationship between the internal physical structure and external electrical parameters of the irradiated thyristor is ***,a series of targeted thyristor physical simulations and neutron irradiation experiments are conducted to verify the accuracy of the theoretical *** addition,the effect of irradiated thyristor electrical characteristic changes on the entire QPS is studied by accurate simulation,providing valuable guidelines for the maintenance and renovation of the QPS.

关键词： Fusion device Neutron irradiation effects Thyristor Quench protection

Electrochemically recycling degraded superalloy and valorizing CO_(2)in the aff ordable borate-modified molten electrolyte

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Tungsten 2024年第2期6卷 382-393页

作者： Xiang Chen Yuan Sun Long Wang Xin Qu Yan Zhao Hong-Wei Xie Di-hua Wang hua-Yi Yin Key Laboratory for Ecological Metallurgy of Multimetallic Mineral of Ministry of Education School of MetallurgyNortheastern UniversityShenyang 110819China Institute of Metal Research Chinese Academy of ScienceShenyang 110016China School of Resource and Environmental Science Wuhan UniversityWuhan 430072China

Integrating electrochemical reduction of CO_(2)and electrochemical oxidation to recycle degraded superalloys is a promising solution to ease resource scarcity and safeguard environmental ***,we propose an electrochemical technique for the conversion of bulk superalloy scraps and CO_(2)into oxide powder at the anode and solid carbon at the cathode,*** particular,a borax-modifi ed CaCl_(2)-based molten salt electrolyte is used for enhancing the electrochemical oxidation of superalloy *** a temperature of 700℃and a voltage of 2.8 V,90.55 wt.%of alloy scraps were oxidized in a molten CaCl_(2)–NaCl–CaCO_(3)–Na_(2)B_(4)O_(7)with an acid–base ratio(K_(a/b))of *** synergy of Cl−and B_(4)O_(7)2−of electrolyte prevents the passivation of the alloy anode and enables continuous ***,the Ni and Co in the anode products are recovered by sulfation roasting with recovery efficiencies of 85.58%and 95.27%for Ni and Co,***,modulating the alkalinity of the electrolyte for enhancing oxidation/pulverization of alloy scrap anode provides new insight into electrochemically recovering superalloy scraps.

关键词： Superalloy scraps Recycling Molten salt Alkalinity Electrochemical oxidation Cobalt

The largest CPIES array in the marginal sea:abundant dynamics in the northeast South China Sea

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Acta Oceanologica Sinica 2024年第1期43卷 135-137页

作者： hua Zheng Xiao-hua Zhu Min Wang Ruixiang Zhao Chuanzheng Zhang Feng Nan Fei Yu Institute of Polar and Ocean Technology Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China National Marine Environmental Monitoring Center Dalian 116023China Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Laboratory for Ocean and Climate Dynamics Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China

The South China Sea(SCS)is a marginal sea connecting the Pacific and Indian oceans and has gained much attention in recent *** dynamics in the northeast SCS are considerably influenced by topography,monsoons,tropical ... 详细信息

关键词： northeast marginal abundant

Cr-catalyzed allylic C(sp^(3))–H addition to aldehydes enabled by photoinduced ligand-to-metal charge transfer

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Science China Chemistry 2024年第5期67卷 1589-1595页

作者： Xianrong Zeng Feng-hua Zhang Runchen Lai Xiaoyu Lin Zhaobin Wang Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province Department of ChemistrySchool of Science and Research Center for Industries of the FutureWestlake UniversityHangzhou 310030China Institute of Natural Sciences Westlake Institute for Advanced StudyHangzhou 310024China Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province Instrumentation and Service Center for Molecular SciencesWestlake UniversityHangzhou 310024China

Photoinduced ligand-to-metal charge transfer(LMCT) has emerged as an effective strategy for synthesizing organic molecules in a sustainable manner. However, the majority of existing reports on selective C(sp^(3))–H bond functionalization via photoinduced LMCT focus on the use of late transition metals or rare-earth metals for radical additions or cross-couplings. In contrast, the utilization of photoinduced LMCT with 3d early transition metals poses a significant challenge. Herein, we describe an unprecedented approach to allylic C(sp^(3))–H addition to aldehydes, employing chromium(Cr) complexes as catalysts through visible-light-induced LMCT. By investigating the reaction pathway through various mechanistic studies, including radical trapping, kinetic isotope effect(KIE) analysis, and transient absorption spectroscopy, valuable insights have been gained. The proposed mechanism suggests the intermediacy of bromine radicals through homolysis of the Cr–Br bond. Notably, this protocol expands our understanding of the photochemical properties of earth-abundant Cr complexes.

关键词： Cr catalysis photoinduced ligand-to-metal charge transfer hydrogen-atom transfer carbonyl addition

Effect of Mo and cold forging deformation on strength and ductility of cobalt-based alloy L605

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Journal of Iron and Steel Research International 2024年第7期31卷 1811-1823页

作者： Zhong-lin Wang Zhi-hua Gong Quan Li Han-sheng Bao School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014017Inner MongoliaChina Institute of Special Steels Central Iron and Steel Research Institute Co.Ltd.Beijing 100081China

Mo element was added to cobalt-based alloy L605,and cold forging deformation was *** effects of the addition and cold forging deformation on the microstructure and mechanical properties of the alloy were studied by thermodynamic calculation,electron backscatter diffraction,transmission electron microscopy,and X-ray *** stacking fault energy(SFE)of the alloy decreased after the addition,and the formation of stacking faults and intersections were promoted to improve the strength and *** tensile strength of the alloy with Mo increased from 1190 to 1702 MPa after 24%cold deformation,producing significant work *** strengthening mechanism is strain-induced martensitic transformation(SIMT)and deformation *** alloy,combined with Mo and after 24%deformation,had both high strength and ductility in comparison with the original cobalt-based alloy *** is attributed to the lower SFE which caused the increase in stacking fault *** the tensile process,theε-hcp phase was easily generated at the stacking fault to reduce the stress concentration and increase the *** SIMT by adjusting the density of stacking faults can improve the mechanical properties of cobalt-based ***ε-hcp phase,the interaction between deformation twins and dislocations,and the interaction between e-hcp phases during cold forging deformation caused local stress concentration,lowering ductility and toughness.

关键词： Cobalt-based alloy-Stacking fault energy Strain-induced martensitic transformation Deformation twin Cold forging deformation

A Secure Mutual Authentication Protocol Based on Visual Cryptography Technique for IoT-Cloud

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Chinese Journal of Electronics 2024年第1期33卷 43-57页

作者： Brou Bernard Ehui Chen CHEN Shirui WANG hua GUO Jianwei LIU School of Cyber Sciences and Technology Beihang University State Key Laboratory of Software Development Environment Beihang University Sino-French Engineering School Beihang University Beihang Hangzhou Innovation Institute Yuhang

Because of the increasing number of threats in the IoT cloud, an advanced security mechanism is needed to guard data against hacking or attacks. A user authentication mechanism is also required to authenticate the user accessing the cloud services. The conventional cryptographic algorithms used to provide security mechanisms in cloud networks are often vulnerable to various cyber-attacks and inefficient against new attacks. Therefore,developing new solutions based on different mechanisms from traditional cryptography methods is required to protect data and users’ privacy from attacks. Different from the conventional cryptography method, we suggest a secure mutual authentication protocol based on the visual cryptography technique in this paper. We use visual cryptography to encrypt and decrypt the secret images. The mutual authentication is based on two secret images and *** user requests the ticket from the authentication server(AS) to obtain the permission for accessing the cloud services. Three shared secret keys are used for encrypting and decrypting the authentication process. We analyze the protocol using the Barrows-Abadi-Needham(BAN)-logic method and the results show that the protocol is robust and can protect the user against various attacks. Also, it can provide a secure mutual authentication mechanism.

关键词： Visualization Cloud computing Data privacy Protocols Biometrics (access control) Authentication Resists