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Parametric study on contact sensors for MASW measurement-based interfacial debonding detection for SCCS

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 331-344页

作者： chen Hongbing Pang xin Gan Shiyu li Yuanyuan Gokarna Chalise Nie xin Research Institute of Urbanization and Urban Safety School of Civil and Resource EngineeringUniversity of Science and Technology BeijingBeijing 100083China Department of Civil Engineering Tsinghua UniversityBeijing 100084China Faculty of Infrastructure Engineering Dalian University of TechnologyDalian 116081China

Steel-concrete composite structures(SCCS)have been widely used as primary load-bearing components in large-scale civil *** the basis of the co-working ability of steel plate and concrete,the bonding status plays an essential role in guaranteeing the structural performance of ***,efficient non-destructive testing(NDT)on interfacial debondings in SCCS has become a prominent research ***-channel analysis of surface waves(MASW)has been validated as an effective NDT technique for interfacial debonding detection for ***,the feasibility of MASW must be validated using experimental *** study establishes a high-frequency data synchronous acquisition system with 32 channels to perform comparative verification experiments in ***,the current sensing approaches for high-frequency vibration and stress waves are ***,three types of contact sensors,namely,piezoelectric lead-zirconate-titanate(PZT)patches,accelerometers,and ultrasonic transducers,are selected for MASW ***,the selection and optimization of the force hammer head are *** experiments are carried out for the optimal selection of ultrasonic transducers,PZT patches,and accelerometers for MASW *** addition,the influence of different pasting methods on the output signal of the sensor array is *** results indicate that optimized PZT patches,acceleration sensors,and ultrasonic transducers can provide efficient data acquisition for MASW-based non-destructive *** research findings in this study lay a solid foundation for analyzing the recognition accuracy of contact MASW measurement using different sensor arrays.

关键词： steel-concrete composite structures(SCCS) interface debonding detection multi-channel analysis of surface waves(MASW) sensor selection comparative experimental study

Surgical treatment of brachiocephalic vessel involvement in Takayasu＇s arteritis

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Chinese Medical Journal 2010年第9期123卷 1122-1126页

作者： WU xin DUAN Hong-yong GU Yong-quan li Jian-xin chen Bing WANG Zhong-gao ZHANG Jian Department of Vascular Surgery Xuanwu HospitalCapital Medical UniversityBeijing 100053China

Background Takayasu＇s arteritis （TA） is a chronic idiopathic inflammatory disease that affects large and medium size arteries. The brachiocephalic trunk is the most frequently involved site in TA, and multi-vessel lesions are common. Surgical treatment includes vessel reconstruction surgery and percutaneous transluminal angioplasty （PTA）. Herein, we report our preliminary experience with surgical treatment of cerebral ischemia caused by cervical arterial lesions due to *** From January 2000 to December 2007, 38 patients with cerebral ischemia caused by cervical arterial occlusive lesions due to TA were treated surgically. There were three males and 35 females, with an age range of 15-42 years （mean 26.5 years）. All patients had operative repairs undertaken. Twenty eight patients received bypass operation and 10 patients received percutaneous transluminal angioplasty. One case with coronary stenosis received coronary artery bypass simultaneously. Patients were followed up for 11 months to eight *** There were no peri-operative deaths in cerebrovascular reconstruction patients. Symptoms of cerebral ischemia were improved or cured in 25 of 38 patients. There was a low incidence of cerebral reperfusion syndrome. Two patients died at five and seven years after surgery due to heart failure. Another 8 patients （20%） required further surgery for stenosis （5 patients） or anastomotic aneurysms （3 patients）. Percutaneous transluminal angioplasty was performed successfully for treatment of aortic and renal lesions. Repeated angioplasty for revascularization was performed in six PTA cases with restenosis after 5-24 *** When cerebral perfusion has potential to be affected by TA, a definitive corrective procedure is advised when the patient is relatively stable. Although the recurrence rate is very high, percutaneous transluminal angioplasty is the first choice procedure. Bypass operation is optimal for brachiocephalic-vessel involvement in TA. Cere

关键词： Takayasu's arteritis brain ischemia brachiocephalic trunk surgical procedures operative reperfusion syndrome

Learning Scalable Task Assignment with Imperative-Priori Conflict Resolution in Multi-UAV Adversarial Swarm Defense Problem

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Journal of Systems Science & Complexity 2024年第1期37卷 369-388页

作者： ZHAO Zhixin chen Jie xin Bin li li JIAO Keming ZHENG Yifan School of Electronics and Information Engineering Tongji UniversityShanghai 201804China Shanghai Institute of Intelligent Science and Technology Tongji UniversityShanghai 201804China School of Automation Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Autonomous Intelligent Unmanned Systems Beijing 100081China Shanghai Institute of Intelligent Science and Technology Tongji UniversityShanghai 201804China.

The multi-UAV adversary swarm defense(MUASD)problem is to defend a static base against an adversary UAV swarm by a defensive UAV *** the problem into task assignment and low-level interception strategies is a widely used ***-based approaches for task assignment are a promising *** studies on learning-based methods generally assume decentralized decision-making architecture,which is not beneficial for conflict *** contrast,centralized decision-making architecture is beneficial for conflict resolution while it is often detrimental to *** achieve scalability and conflict resolution simultaneously,inspired by a self-attention-based task assignment method for sensor target coverage problem,a scalable centralized assignment method based on self-attention mechanism together with a defender-attacker pairwise observation preprocessing(DAP-SelfAtt)is ***,an imperative-priori conflict resolution(IPCR)mechanism is proposed to achieve conflict-free ***,the IPCR mechanism is parallelized to enable efficient *** validate the algorithm,a variant of proximal policy optimization algorithm(PPO)is employed for training in scenarios of various *** experimental results show that the proposed algorithm not only achieves conflict-free task assignment but also maintains scalability,and significantly improve the success rate of defense.

关键词： Conflict resolution reinforcement learning scalability task assignment.

NHC-derived carbon-centered luminescent radicals with shortwavelength emission via suppression of Kasha's rule

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Science China Chemistry 2024年第8期67卷 2679-2685页

作者： Can chen xin li xinhua Ouyang Ying-Feng Han Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education Xi’an Key Laboratory of Functional Supramolecular Structure and MaterialsCollege of Chemistry and Materials ScienceNorthwest UniversityXi’an 710127China College of Material Engineering Fujian Agriculture and Forestry University Fuzhou 350108China

Luminescent organic radicals have garnered increasing attention owing to their versatile applications in sensing, imaging, and organic light-emitting diodes(OLEDs), attributed to their unique emission properties originating from the doublet spin ***, the natural narrow bandgap of organic free radicals typically limits their emission to the long-wavelength *** luminescent organic radicals with short-wavelength emission remains a significant challenge. Herein, a series of carbon-centered radicals with short-wavelength emission(383–476 nm) by combining N-heterocyclic carbenes with various polycyclic aromatic hydrocarbons(PAHs)(2-naphthyl, 2a~Ⅰ and 2b~Ⅰ;2-phenanthryl, 2a~Ⅱand 2b~Ⅱ;2-anthryl, 2a~Ⅲand 2b~Ⅲ;3-phenanthryl, 2a~Ⅳand 2b~Ⅳ). Theoretical calculations reveal that the introduction of PAHs significantly increases the ΔE_(D2-D1) in 2a^(Ⅰ–Ⅲ)and 2b^(Ⅰ–Ⅲ)compared to that in phenyl-derived radical congeners. Consequently, the internal transition from D2 to D1 is impeded, leading to a high yield of D2 emission and a suppressed Kasha's rule, thereby overcoming the limitations imposed by their narrow bandgap. For 2a~Ⅳ and 2b~Ⅳ, despite a moderately large ΔED2-D1value, the ΔED3-D1value exceeds 1 e V, indicating that their emission likely originates from the D3 state. Furthermore, we utilized 2a~Ⅲand 2b~Ⅲ as emissive materials in OLEDs,resulting in blue emissions with external quantum efficiencies of 7.5% and 6.5%, respectively.

关键词： N-heterocyclic carbenes luminescent organic molecules carbon-centered radicals short-wavelength emission

Tensile strength behavior of cement-stabilized dredged sediment reinforced by polypropylene fiber

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Frontiers of Structural and Civil Engineering 2024年第3期18卷 380-392页

作者： Lei LANG Jiangshan li xin chen lijun HAN Ping WANG State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicChinese Academy of SciencesWuhan 430071China Hubei Provincial Key Laboratory of Contaminated Sludge and Soil Science and Engineering Wuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

This study evaluated the feasibility of using polypropylene fiber(PF)as reinforcement in improving tensile strength behavior of cement-stabilized dredged sediment(CDS).The effects of cement content,water content,PF content and length on the tensile strength and stress–strain behavioral evolutions were evaluated by conducting splitting tensile strength ***,the micro-mechanisms characterizing the tensile strength behavior inside PF-reinforced CDS(CPFDS)were clarified via analyzing macro failure and microstructure *** results indicate that the highest tensile strengths of 7,28,60,and 90 d CPFDS were reached at PF contents of 0.6%,1.0%,1.0%,and 1.0%,exhibiting values 5.96%,65.16%,34.10%,and 35.83%higher than those of CDS,***,3 mm,PF of showed the best reinforcement *** CPFDS exhibited obvious tensile strain-hardening characteristic,and also had better ductility than *** mix factor(C_(C)^(a)/C_(w)^(b))and time parameter(q_(t0)(t))of CDS,and the reinforcement index(k_(t-PF))of CPFDS were used to establish the tensile strength prediction models of CDS and CPFDS,considering multiple *** PF“bridge effect”and associated cementation-reinforcement coupling actions inside CPFDS were mainly responsible for tensile strength behavior *** key findings contribute to the use of CPFDS as recycled engineering soils.

关键词： dredged sediment chemical stabilization fiber reinforcement splitting tensile strength micro-mechanisms

Experimental study on the size effect on the equation of state of concretes under shock loading

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Defence Technology（防务技术） 2024年第3期33卷 160-167页

作者： Mei li Jian Cui Yanchao Shi Baijian Tang xin chen Key Laboratory of Coast Civil Structural Safety of the Ministry of Education Tianjin UniversityTianjin 300072China School of Civil Engineering Suzhou University of Science and Technology1701 Binhe RoadSuzhou 215011JiangsuChina School of Civil Engineering Tianjin UniversityTianjin 300072China

Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of *** experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the *** some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one *** this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete *** mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the *** to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.

关键词： Concrete Equation of state Size effect Shock wave Fly-plate impact test

Asymmetric alkenylation reaction of benzoxazinones with diarylethylenes catalyzed by B(C_(6)F_(5))_(3)/chiral phosphoric acid

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Chinese Chemical Letters 2024年第5期35卷 135-140页

作者： Zhen liu Zhi-Yuan Ren chen Yang Xiangyi Shao li chen xin li State Key Laboratory of Elemento-Organic Chemistry Frontiers Science Center for New Organic MatterCollege of ChemistryNankai UniversityTianjin 300071China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China Zhenhai High School of Zhejiang Ningbo 315299China

Catalytic enantioselective alkenylation is an efficient method to construct chiral alkene molecules,but the asymmetric alkenylation of simple alkenes catalyzed by metal-free catalysts remains an elusive ***,we reported an asymmetric alkenylation of benzoxazinones with diarylethylenes by utilizing a B(C_(6)F_(5))_(3)/chiral phosphoric acid catalyst.A broad of benzoxazinones and diarylethylenes with electron-withdrawing and electron-donating groups were tolerated(up to 95%yield and 97.5:2.5 e.r.)in the methodology under mild reaction ***,the synthetic utility was confirmed by the scaled-up reaction and transformations of the *** mechanism was preliminarily explored by control reactions,nonlinear effect experiment and DFT calculations.

关键词： Asymmetric alkenylation Simple alkenes Benzoxazinones B(C_(6)F_(5))_(3)/chiral phosphoric acid Theoretical calculations

Efficient capture of difluorocarbene by pyridinium 1,4-zwitterionic thiolates:A concise synthesis of difluoromethylene-containing 1,4-thiazine derivatives

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Chinese Chemical Letters 2024年第4期35卷 367-370页

作者： Zhiwei chen Heyun Sheng Xue li Menghan chen xin li Qiuling Song Institute of Next Generation Matter Transformation College of Materials Science&Engineering and College of Chemical Engineering at Huaqiao UniversityXiamen 361021China Fujian University Key Laboratory of Molecule Synthesis and Function Discovery College of ChemistryFuzhou UniversityFuzhou 350108China State Key Laboratory of Organometallic Chemistry and Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

A practical method for the construction of difluoromethylene-containing 1,4-thiazine moieties using readily available diethyl bromodifluoromethanephosphonate(BrCF_(2)PO(OEt)_(2))as difluorocarbene precusor has been *** transformation features the efficient capture of difluorocarbene by pyridinium 1,4-zwitterionic thiolates.A series of structurally novel and functionalized difluoromethylene-containing 1,4-thiazine derivatives were thus synthesized in good yields.

关键词： Difluoromethylene Pyridinium 1 4-zwitterionic thiolates 1 4-Thiazine derivatives

Multiplicity of solutions for the semilinear subelliptic Dirichlet problem

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Science China Mathematics 2024年第3期67卷 475-504页

作者： Hua chen Hong-Ge chen Jin-Ning li xin liao School of Mathematics and Statistics Wuhan UniversityWuhan 430072China Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

In this paper,we study the semilinear subelliptic equation{−△Xu=f(x,u)+g(x,u)inΩ,u=0 on∂Ω,where△X=−∑m i=1 Xi∗Xi is the self-adjoint Hormander operator associated with the vector fields X=(X_(1),X_(2),...,X_(m))satisfying the Hormander's condition,f(x,u)∈C(Ω×R),g(x,u)is a Carathéodory function onΩ×R,andΩis an open bounded domain in R~n with smooth *** the perturbation from the symmetry method with the approaches involving the eigenvalue estimate and the Morse index in estimating the minimax values,we obtain two kinds of existence results for multiple weak solutions to the problem ***,we discuss the difference between the eigenvalue estimate approach and the Morse index approach in degenerate *** with the classical elliptic cases,both approaches here have their own strengths in the degenerate *** new phenomenon implies that the results in general degenerate cases would be quite different from the situations in classical elliptic cases.

关键词： degenerate elliptic equations Hormander operators perturbation method Morse index