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Continuous Orbit Equivalence of Semigroup Actions

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1581-1598页

作者： Xiang Qi QIANG Cheng Jun hou School of Mathematical Science Yangzhou UniversityYangzhou 225002P.R.China

We introduce notions of continuous orbit equivalence and its one-sided version for countable left Ore semigroup actions on compact spaces by surjective local homeomorphisms,and characterize them in terms of the corresponding transformation groupoids and their operator *** particular,we show that two essentially free semigroup actions on totally disconnected compact spaces are continuously orbit equivalent if and only if there is a canonical abelian subalgebra preserving C^(∗)-isomorphism between the associated transformation groupoid C^(∗)-*** also give some examples of orbit equivalence,consider the special case of semigroup actions by homeomorphisms and relate continuous orbit equivalence of semigroup actions to that of the associated group actions.

关键词： Semigroup action continuous one-sided orbit equivalence continuous orbit equivalence groupoid C^(∗)-algebras

Pixel-level crack segmentation of tunnel lining segments based on an encoder–decoder network

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Frontiers of Structural and Civil Engineering 2024年第5期18卷 681-698页

作者： Shaokang hou Zhigang OU Yuequn HUANG Yaoru LIU State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China China Renewable Energy Engineering Institute Beijing 100120China State Key Laboratory of Stimulation and Regulation of Water Cycles in River Basins China Institute of Water Resources and Hydropower ResearchBeijing 100038China Hunan Provincial Water Resources Development&Investment Co. Ltd.Changsha 410007China

Regular detection and repair for lining cracks are necessary to guarantee the safety and stability of *** development of computer vision has greatly promoted structural health *** study proposes a novel encoder–decoder structure,CrackRecNet,for semantic segmentation of lining segment cracks by integrating improved VGG-19 into the U-Net *** image acquisition equipment is designed based on a camera,3-dimensional printing(3DP)bracket and two laser rangefinders.A tunnel concrete structure crack(TCSC)image data set,containing images collected from a double-shield tunnel boring machines(TBM)tunnel in China,was *** data preprocessing operations,such as brightness adjustment,pixel resolution adjustment,flipping,splitting and annotation,2880 image samples with pixel resolution of 448×448 were *** model was implemented by Pytorch in PyCharm processed with 4 NVIDIA TITAN V *** the experiments,the proposed CrackRecNet showed better prediction performance than U-Net,TernausNet,and *** paper also discusses GPU parallel acceleration effect and the crack maximum width quantification.

关键词： tunnel lining segment crack detection semantic segmentation convolutional neural network encoder-decoder structure

Compositionally graded high-voltage P2-type cathode with superior structural stability and redox kinetics for advanced Na-ion batteries

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Nano Research 2024年第4期17卷 2755-2762页

作者： Peiyu hou Mohan Dong Zhenbo Sun Feng Li School of Physics and Technology University of JinanJinan 250022China

Layered P2-type cathodes with high voltage,large capacity,and easy synthesis show great potential for developing sodium(Na)-ion batteries(NIBs).However,the P2–O2 phase transition makes their structural degradation and the Na^(+)/vacancy ordering lowers their redox ***,we rationally propose a compositionally graded P2-type cathode,where nickel(Ni)and manganese(Mn)fractions decrease gradually,and cobalt(Co)content increases contiguously from the inside to the outside of a secondary *** these particles,the Ni/Mn-based compound delivers high capacity and high *** the surface of particles,the Co/Mn-based solid solution offers a stable buffer *** from these synergistic effects,this graded P2-type cathode shows the elimination of P2–O2 transformation even when charged to 4.4 V,which enables good structural stability,maintaining capacity retention reaching~80%within 300 ***,the Na^(+)/vacancy ordering superstructure is further suppressed,and the Na^(+)diffusion kinetics is significantly *** proposed graded structure with optimized chemical composition offers a new perspective for eliminating the unwanted phase transition and thus enhancing the electrochemistry of high-voltage layered cathodes for advanced NIBs.

关键词： Na-ion battery P2-type cathode composition regulation phase transition redox stability

Metal-organic-framework-derived copper-based catalyst for multicomponent C-S coupling reaction

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Chinese Journal of Chemical Engineering 2024年第6期70卷 1-8页

作者： Lixin Chen Hui Zhang Linxi hou Xin Ge Key Laboratory of Synthetic and Biological Colloids Ministry of EducationSchool of Chemical and Material EngineeringJiangnan UniversityWuxi 214122China Department of Materials-Oriented Chemical Engineering School of Chemical EngineeringFuzhou UniversityFuzhou 350116China Qingyuan Innovation Laboratory Quanzhou 362801China

Copper-based metal-organic frameworks(Cu-MOFs)are a promising multiphase catalyst for catalyzing C-S coupling reactions by virtue of their diverse structures and ***,the unpleasant odor and instability of the organosulfur,as well as the mass-transfer resistance that exists in multiphase catalysis,have often limited the catalytic application of Cu-MOFs in C-S coupling *** this paper,a Cu-MOFs catalyst modified by cetyltrimethylammonium bromide(CTAB)was designed to enhance mass transfer by increasing the adsorption of organic substrates using the long alkanes of ***,elemental sulfur was used to replace organosulfur to achieve a highly efficient and atom-economical multicomponent C-S coupling reaction.

关键词： Design Copper-based metal-organic frameworks (Cu-MOFs) Adsorption C-S coupling reaction Multiphase reaction

A molecular insight into coke formation process of vacuum residue in thermal cracking reaction

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Petroleum Science 2024年第3期21卷 2130-2138页

作者： Ji-Guang Li Xin Guo Huan-Di hou Heavy Oil Processing Department Sinopec Research Institute of Petroleum Processing Co.LtdBeijing100083China

Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with various reaction time were performed to evaluate the coke formation *** total yields of ideal components including naphtha,atmospheric gas oil(AGO)and vacuum gas oil(VGO)of thermal cracking reactions increased from 10.89%to 40.81%,and the conversion ratios increased from8.05%to 43.33%with increasing the reaction time from 10 to 70 *** asphaltene content increased from 12.14%to a maximum of 22.39%and then decreased,and this maximum of asphaltene content occurred at the end of the coking induction *** asphaltenes during the coking induction period,at the end and after coking induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for coke formation process,and the coke formation pathways were discussed to reveal the coke formation process at molecular level.

关键词： Vacuum residue Thermal cracking Asphaltene Coking induction period Sulfur Nitrogen

Investigation of high rate mechanical flow followed by ignition for high-energy propellant under dynamic extrusion loading

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Defence Technology（防务技术） 2024年第2期32卷 336-347页

作者： Liying Dong Yanqing Wu Kun Yang Xiao hou State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident ***, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 22.3 MPa to 28.6 MPa, the critical value of effective plastic work required for ignition is shortened from 1280 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.

关键词： NEPE propellant Crevice extrusion Shear flow Sample thickness Ignition reaction

Direct Conversion of Methane to Propylene

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Research 2024年第2期2023卷 463-472页

作者： Yunpeng hou Yuxiang Lan Chao Qian Shaodong Zhou College of Chemical and Biological Engineering Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture TechnologyZhejiang University310027 HangzhouP.R.China Zhejiang Provincial Innovation Center of Advanced Chemicals Technology Institute of Zhejiang University-Quzhou324000 QuzhouP.R.China

Nonoxidative coupling of methane exhibits promising prospect in that it affords value-added hydrocarbons and hydrogen with high atom ***,challenge remains in direct,selective conversion of methane to more valuable hydrocarbons like *** current work presents a catalyst with well-dispersed Ta atoms anchored by graphitic C_(3)N_(4)-supported *** a catalyst is able to convert methane selectively to ethylene and propylene at a relatively low temperature(350℃).The conception of the active center and construction of the catalyst have been described,and the origins of the catalytic performance are discussed.

关键词： methane catalyst hydrocarbons

Terminal attitude selection method of missile attack aircraft

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Chinese Journal of Aeronautics 2024年第2期37卷 385-400页

作者： Peng hou Yang PEI Yuxue GE Mengjie ZHU School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Research Department Shanghai Electro-Mechanical Engineering InstituteShanghai 201108China

The appropriate terminal attitude of missile is important to improve the damage effectiveness of fragmentation warhead against aircraft *** this paper,three missile terminal attitude selection methods are proposed to solve the problem of terminal attitude selection in different situations according to their respective evaluation *** MVE-based method uses the damage probability of each detonation point around the aircraft at a given attitude of missile to calculate the Mean Volume of Effectiveness(MVE)at the corresponding attitude,and then uses the MVE for different attitudes to select the terminal strike *** detonation position-based method addresses the case where the missile detonation position can be assessed in *** the effects of missile guidance errors and fuze activation position errors,Monte Carlo simulations are used to calculate the damage probability of aircraft with different strike attitudes,from which the terminal strike attitude is *** BP-ANN model-based method uses the constructed Back Propagation Artificial Neural Network(BP-ANN)model instead of simulation to calculate the evaluation indexes in the corresponding cases of MVE-based method and Detonation position-based method,which can improve the efficiency of attitude *** are conducted for different scenarios to verify the feasibility and effectiveness of the proposed method.

关键词： Aircraft vulnerability Attitude selection BP-ANN Damage probability Damage effectiveness

Dual Frequency Transformer for Efficient SDR-to-HDR Translation

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Machine Intelligence Research 2024年第3期21卷 538-548页

作者： Gang Xu Qibin hou Ming-Ming Cheng Tianjin Media Computing Center College of Computer ScienceNankai UniversityTianjin300000China

The SDR-to-HDR translation technique can convert the abundant standard-dynamic-range (SDR) media resources to high-dynamic-range (HDR) ones, which can represent high-contrast scenes, providing more realistic visual experiences. While recent vision Transformers have achieved promising performance in many low-level vision tasks, there are few works attempting to leverage Transformers for SDR-to-HDR translation. In this paper, we are among the first to investigate the performance of Transformers for SDR-to-HDR translation. We find that directly using the self-attention mechanism may involve artifacts in the results due to the inappropriate way to model long-range dependencies between the low-frequency and high-frequency components. Taking this into account, we advance the self-attention mechanism and present a dual frequency attention (DFA), which leverages the self-attention mechanism to separately encode the low-frequency structural information and high-frequency detail information. Based on the proposed DFA, we further design a multi-scale feature fusion network, named dual frequency Transformer (DFT), for efficient SDR-to-HDR translation. Extensive experiments on the HDRTV1K dataset demonstrate that our DFT can achieve better quantitative and qualitative performance than the recent state-of-the-art methods. The code of our DFT is made publicly available at https://***/CS-GangXu/DFT.

关键词： Standard-dynamic-range to high-dynamic-range(SDR-to-HDR)translation Transformer dual frequency attention(DFA) frequency-aware feature decomposition efficient model