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MOF-derived Co9S8/MoS2 embedded in tri-doped carbon hybrids for efficient electrocatalytic hydrogen evolution

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Journal of Energy Chemistry 2020年第5期29卷 90-96页

作者： tian-tian chen Rui Wang Lin-Ke Li Zhong-Jun Li Shuang-Quan Zang College of Chemistry and Molecular Engineering Zhengzhou UniversityZhengzhou 450001HenanChina

Metal-organic framework(MOF)derived hybrid materials have been developed as an efficient non-noblemetal electrocatalysts for clean energy conversion *** this work,a Co-based MOF containing nitrogen and oxygen heteroatoms(Co-NOMOF)mixed with the thiomolybdate[Mo3S(13)]^2- nanoclusters was used to prepare the N,S,O-doped carbon encapsulating Co9S8 and MoS2(Co9S8/MoS2@NSOC)nanocomposite by one-step *** Co9S8/MoS2@NSOC nanocomposite exhibited remarkable catalytic performance for hydrogen evolution reaction(HER)with overpotential of 194 and 233 mV in 1 M KOH and 0.5 M H2SO4 solution under 10 mA cm^-2,respectively,which was ascribed to the multiheteroatom-doped hierarchical porous carbon matrix and the synergistic effect of intrinsic activity of Co9S8 and *** work provides new opportunity for developing highly efficient non-precious metal electrochemical catalysts.

关键词： Metal-organic frameworks Hydrogen evolution reaction [Mo3S13]2^-clusters Co9S8

Sulfamic acid as a cost-effective and recyclable solid acid catalyst for Friedel-Crafts alkylation of indole withα,β-unsaturated carbonyl compound and benzyl alcohol

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Chinese Chemical Letters 2011年第12期22卷 1391-1394页

作者： Jing Yang Juan Zhang tian tian chen De Mei Sun Ji Li Xue Fen Wu Henan University of Traditional Chinese Medicine Zhengzhou 450008 China Henan Chemical Industry Research Institute Co. Ltd. Zhengzhou 450052 China Institute of Chemistry Henan Academy of Science Zhengzhou 450002 China

Sulfamic acid was proved to be a cost-effective and recyclable catalyst for Friedel-Crafts type reaction of indole withα,β-unsaturated carbonyl compound and benzyl *** indoles,α,β-unsaturated carbonyl compounds and a benzyl alcohol were successfully used in this type of reaction,and the corresponding products were obtained in good to excellent yields.

关键词： Sulfamic acid Michael reaction of indole Acid catalysis Alkylation of indole with benzyl alcohol

Frost heaving and crack initiation characteristics of tunnel rock mass in cold regions under low-temperature degradation

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Journal of Mountain Science 2024年第8期21卷 2844-2854页

作者： chen Wenhua XIANG tian School of Civil Engineering Beijing Jiaotong UniversityBeijing 202303China

Water freezing in rock fractures causes volumetric expansion and fracture development through frost *** study introduces a novel analytical model to investigate how uneven freezing force and surrounding rock pressure influence fracture initiation,based on mass conservation,elasticity,and water-ice phase transition principles.A model for rock fracture initiation considering freezing temperature,uneven freezing expansion,in-situ stress,and lateral pressure was proposed based on fracture *** for stress intensity factors were developed and validated using the phase field *** effects of rock elastic modulus anisotropy and critical fracture energy density on fracture initiation were also *** results show that the values of KI and KII exhibit an upward trend as the freezing temperature,uneven expansion,in-situ stress,and lateral pressure *** uneven freezing expansion has the most significant influence on KI and KII values among these *** the uneven freezing expansion coefficient increases to 0.5,the fracture initiation mode shifts from tensile fracture to shear *** the lateral pressure coefficient increases to 1,the fracture initiation mode shifts from tensile fracture to shear *** elastic modulus anisotropy causes fractures to propagate in a clockwise direction,forming a'butterfly'*** fracture energy density an isotropy causes counterclockwise deviation in propagation direction,resulting in branching paths and an'H'-shaped pattern.

关键词： Rock fractures Fracture water Uneven freezing expansion Phase field method Initiation angle Anisotropy

Evolution of suspension bridge structural systems,design theories,and shape-finding methods:A literature survey

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第2期11卷 225-244页

作者： Wenming Zhang Genmin tian Yupeng chen Key Laboratory of Concrete and Pre-stressed Concrete Structures of Ministry of Education Southeast UniversityNanjing 210096China State Key Laboratory of Safety Durability and Healthy Operation of Long Span BridgesSoutheast UniversityNanjing 210096China

Modern suspension bridges exhibit a trend of lighter structures,more diversified structural forms,and longer spans,the latter already exceeding two *** performance under dead and live loads depends on their structural and main cable systems,while cablesupported bridges especially rely on the design analysis and construction control of the main *** literary survey systematically analyzes the research progress and state-ofthe-art status quo in the structural systems and design theories of suspension bridges,focusing on the structural systems,main cable shape analyses,live load effect analyses,and emerging lucrative research *** than 100 reliable references have been surveyed.(1)Multi-span or multi-main cable schemes appeal to increasing attention,which may become a better choice in terms of structural systems in scenarios with extremely long spans and heavy *** cable layouts,such as spatial main cables and hybrid cable-stayed suspension systems have also become feasible approaches for enhancing structural stiffness.(2)The shape-finding analysis during the construction phase is more complex and has more essential factors than that of the completed bridge *** theories combining analytical methods and finite element methods are more suitable for the shape-finding analysis of complex cable systems than any single theory of the two,especially for novel cable systems.(3)The live load effect analysis methods based on traditional deflection theory or modified/improved deflection theories still have wide applications,but the refined theory of treating hangers as discrete members is also constantly developing,which is expected to provide new ideas for more complex structural analysis under the different types of live loads and their distribution forms.

关键词： Suspension bridges Structural system Cable analysis Shape-finding analysis Construction control and calculation Live load effect

Topologically protected entanglement switching around exceptional points

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Light(Science & Applications) 2024年第8期13卷 1631-1644页

作者： Zan Tang tian chen Xing Tang Xiangdong Zhang Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology100081 BeijingChina

The robust operation of quantum entanglement states is crucial for applications in quantum information,computing,and communications^(1–3).However,it has always been a great challenge to complete such a task because of decoherence and ***,we propose theoretically and demonstrate experimentally an effective scheme to realize robust operation of quantum entanglement states by designing quadruple degeneracy exceptional *** encircling the exceptional points on two overlapping Riemann energy surfaces,we have realized a chiral switch for entangled states with high *** to the topological protection conferred by the Riemann surface structure,this switching of chirality exhibits strong robustness against perturbations in the encircling ***,we have experimentally validated such a scheme on a quantum walk *** work opens up a new way for the application of non-Hermitian physics in the field of quantum information.

关键词： exceptional quantum Riemann

Short-time maritime target detection based on polarization scattering characteristics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 55-64页

作者： chen Shichao LUO Feng tian Min LYU Wanghan College of Computer and Information Engineering(College of Artificial Intelligence) Nanjing Tech UniversityNanjing 211816China Hangzhou Institute of Technology Xidian UniversityHangzhou 311200China

In this paper,a detection method combining Cameron decomposition based on polarization scattering characteristics in sea clutter background is ***,the Cameron decomposition is exploited to fuse the radar echoes of full polarization channels at the data *** to the artificial material structure on the surface of the target,it can be shown that the non-reciprocity of the target cell is stronger than that of the clutter ***,based on the analysis of the decomposition results,a new feature with scattering geometry characteristics in polarization domain,denoted as Cameron polarization decomposition scattering weight(CPD-SW),is extracted as the test statistic,which can achieve more detailed descriptions of the clutter scattering characteristics utilizing the difference between their scattering ***,the superiority of the proposed CPD-SW detector over traditional detectors in improving detection performance is verified by the IPIX measured dataset,which has strong stability under short-time observation in threshold detection and can also improve the separability of feature space zin anomaly detection.

关键词： sea clutter small target radar detection Cameron decomposition characteristics analysis

Design of acceleration control schedule for adaptive cycle engine based on direct simulation model

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Chinese Journal of Aeronautics 2024年第6期37卷 307-318页

作者： Keran SONG Linyuan JIA Yuchun chen tian TAN School of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China

To design the optimum acceleration control schedule for the Adaptive Cycle Engine(ACE)in the full flight envelope,this paper establishes a direct simulation model of the ACE transient *** this model,geometric parameters are used to replace the component state *** corresponding relationship between geometric parameters and component state parameters is determined by sensitivity *** geometric variables are controlled when the geometric adjustment speed exceeds the limit,and at the same time the corresponding component state parameters are *** gradient optimization algorism is used to optimize the ground acceleration process of ACE,and the control schedule in terms of operating point of compression components and corrected acceleration rate is used as the full-envelope acceleration control schedule based on the similarity *** acceleration control schedules of the triple-bypass mode and the double-bypass mode are designed in this *** acceleration processes under various flight conditions are simulated using the acceleration control *** with the acceleration process with the linear geometric adjustment schedule,the acceleration performance of ACE is improved by the acceleration control schedule,with the impulse of the acceleration process of the triple-bypass mode being increased by 8.7%-12.3% and the impulse of the double-bypass mode acceleration process being increased by 11.8%-14.1%.

关键词： Adaptive Cycle Engine(ACE) Direct simulation method Acceleration Control schedule Full flight envelope

Interfacial tribochemical kinetics: A new perspective on superlubricity of diamond-like carbon films

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Science China(Technological Sciences) 2024年第7期67卷 2050-2052页

作者： chen WeiQi MA tian-Bao State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

Friction is considered one of the primary challenges affecting the performance of machine operations and is a significant source of energy loss in industrial applications. About 30%of disposable energy is consumed by ... 详细信息

关键词： kinetics friction operations

A dynamical neural network approach for distributionally robust chance-constrained Markov decision process

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Science China Mathematics 2024年第6期67卷 1395-1418页

作者： tian Xia Jia Liu Zhiping chen School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an710049China

In this paper,we study the distributionally robust joint chance-constrained Markov decision *** the logarithmic transformation technique,we derive its deterministic reformulation with bi-convex terms under the moment-based uncertainty *** cope with the non-convexity and improve the robustness of the solution,we propose a dynamical neural network approach to solve the reformulated optimization *** results on a machine replacement problem demonstrate the efficiency of the proposed dynamical neural network approach when compared with the sequential convex approximation approach.

关键词： Markov decision process chance constraints distributionally robust optimization moment-based ambiguity set dynamical neural network