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Reducing aerodynamic vibration of rigid rotors with retreating side active control avoidance

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Chinese Journal of Aeronautics 2025年第1期38卷 353-364页

作者： Weiliang LYU School of Mechanics and Aerospace Engineering Dalian University of TechnologyDalian 116024China

This paper proposes a new approach to eliminate aerodynamic lift oscillation,called the Dominant Sector Individual Blade Control(DS-IBC)method for rigid rotor *** Advancing Blade Concept(ABC)rotor model for aerodynamic analysis based on the free-wake method is ***-IBC avoids applying active control on the rotor's retreating side by employing and restricting active control inputs to a sector area of the rotor *** this sector,only primary collective and cyclic pitch control are *** blade takes turns entering the sector,creating a“relay”active control form to ensure continuous control *** method also includes outer-trim and inner-trim iteration *** show that DS-IBC can eliminate aerodynamic lift oscillation using much smaller control inputs than the sine-trim *** focusing active control on the rotor's advancing side,DS-IBC improves the effective lift-to-drag ratio and reduces the implementation difficulty of active rotor control for aerodynamic oscillation elimination,especially at a large lift-offset.

关键词： Advancing blade concept Lift-offset Rigid rotor Aerodynamic lift oscillation Dominant Sector Individual Blade Control(DS-IBC)

Tail Dependence Matrices and Tests Based on Spearman's ρ and Kendall's τ

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Acta Mathematica Sinica,English Series 2025年第2期41卷 522-546页

作者： Lingyue Zhang Dawei Lu Hengjian Cui School of Mathematical Sciences Capital Normal UniversityBeijing 100048P.R.China School of Mathematical Sciences Dalian University of TechnologyDalian 116024P.R.China

Measuring and testing tail dependence is important in finance, insurance, and risk management. This paper proposes two tail dependence matrices based on classic rank correlation coefficients,which possess the desired population properties and interpretability. Their nonparametric estimators with strong consistency and asymptotic distributions are derived using the limit theory of *** simulation and application studies show that, compared to the tail dependence matrix based on Spearman's ρ with large deviation, the Kendall-based tail dependence measure has stable variances under different tail conditions;thus, it is an effective approach to testing and quantifying tail dependence between random variables.

关键词： Tail dependence Spearman's Kendall's -statistic Copula

Synthesis of ordered mesoporous crystalline boron phosphate scaffold with double diamond surface structure

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Science China Chemistry 2025年第2期68卷 590-600页

作者： Chao Wang Wen-Duo Lu Jiao Wang Shunai Che An-Hui Lu Lu Han School of Chemical Science and Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Fine Chemicals Liaoning Key Laboratory for Catalytic Conversion of Carbon ResourcesSchool of Chemical EngineeringDalian University of TechnologyDalian 116024China School of Chemistry and Chemical Engineering Frontiers Science Center for Transformative MoleculesState Key Laboratory of Metal Matrix CompositesShanghai Key Laboratory for Molecular Engineering of Chiral DrugsShanghai Jiao Tong UniversityShanghai 200240China

Ordered mesoporous materials have received great attention due to their well-defined pore structures and potential applications in catalysis,adsorption,separation,drug delivery,*** various compositions of mesoporous solids have been successfully prepared,the preparation of crystalline non-metallic oxyacid salts with ordered mesoporosity remains a major ***,we report the synthesis of a mesoporous solid acid crystalline boron phosphate(BPO_(4))catalyst with a bicontinuous shifted double diamond(SDD)hyperbolic surface *** BPO_(4) scaffold was obtained by synergistic selfassembly in a mixed solvent of water and tetrahydrofuran using the diblock copolymer poly(ethylene oxide)-block-polystyrene as template and phosphoric acid and orthoboric acid as inorganic *** structure consists of two sets of diamond networks adjacent to each other with a mesostructural scale tetragonal symmetry(space group I4_(1)/amd)with unit cell parameters of a=80 nm and c=113 nm,which affords the scaffold a specific surface area of 44 m^(2)/*** a solid acid catalytic material,the SDD BPO_(4) scaffold exhibited excellent catalytic activity at room temperature with a conversion of furfural to 2-(dimethoxymethyl)furan over 70%and can be reused after recovery without serious loss of *** the propane oxidative dehydrogenation reaction,SDD BPO_(4) demonstrated high olefin productivity and selectivity while maintaining high reaction *** study provides ideas for the preparation of ordered mesoporous crystalline catalytic materials and demonstrates their potential for practical applications.

关键词： boron phosphate mesoporous material self-assembly block copolymer catalyst

Cu3.21Bi4.79S9:Bimetal superionic strategy boosts ultrafast dynamics for Na-ion storage/extraction

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Journal of Energy Chemistry 2025年第02期 769-777页

作者： Xu Han Guoping Liu Weiqiang Kong Wenruo Li Shun Liu Luzheng Zhao Haoyuan Zhu Jiancong Guo Zhongsheng Wen Department of Materials Dalian Maritime University School of Materials and Energy Guangdong University of Technology

Traditional metal sulfides used as anodes for sodium-ion batteries are hindered by sluggish kinetics,which limits their rate *** attempts to address this issue focused on nanostructured configurations with conductive ***,these nanomaterials often suffer from low packing density and the tendency for nanoparticles to agglomerate,posing significant challenges for practical *** overcome these limitations,this study presents a novel bimetal superionic anode material Cu3.21Bi4.79S9,which effectively resolves the conflict between sluggish kinetics and micrometer-scale particle *** leveraging the vacancies created by free Cu and Bi atoms,this material forms rapid migration channels during sodium insertion and extraction,significantly reducing the migration barriers for sodium *** development of micrometer-scale Cu3.21Bi4.79S9enables ultrafast chargingdischarging capabilities,achieving a reversible capacity of 325.5 mAh g-1after 4000 cycles at a high rate of 45 C(15 A g-1).This work marks a significant advancement in the field by offering a solution to the inherent trade-off between high capacity and rate performance in coarse-grained materials,reducing the need for reliance on nanostructured configurations for next-generation high-capacity anode materials.

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New analytical solutions for free vibration of embedded magneto-electro-elastic cylindrical shells with step-wise thickness variations

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Applied Mathematics and Mechanics(English Edition) 2025年第3期46卷 447-466页

作者： Jufang JIA Huilin YIN Qinyu YU Jiabin SUN Xinsheng XU Zhenhuan ZHOU School of Mechanical Engineering and Automation Dalian Polytechnic University State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial Equipment School of Mechanics and Aerospace EngineeringDalian University of Technology State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial Equipment School of Chemical Engineering Ocean and Life SciencesDalian University of Technology

In recent years, magneto-electro-elastic(MEE) cylindrical shells with step-wise thicknesses have shown significant potential in the field of vibration energy harvesting. To aid the design of such energy harvesting devices, an accurate free vibration analysis of embedded MEE cylindrical shells with step-wise thicknesses is performed within the framework of symplectic mechanics. By using the Legendre transformation, a new known vector is defined to transform the higher-order partial differential governing equations into a set of lower-order ordinary differential equations. Therefore, the original vibration analysis is regarded as an eigen problem in the symplectic space, and analytical solutions can be represented by the symplectic series. In numerical examples, the new analytical solutions are compared with the existing results, and good agreement is observed. Furthermore, the effects of critical design parameters on free vibration characteristics are thoroughly investigated. All numerical results can serve as benchmarks for the development of other approximate or numerical methods.

关键词： analytical solution cylindrical shell with variable thickness free vibration magneto-electro-elastic (MEE) material O343 symplectic method

Analysis of Nitrate Sources in Different Rivers Flowing into the Sea Based on Nitrogen and Oxygen Isotopes

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Huanjing Kexue/Environmental Science 2025年第3期46卷 1371-1381页

作者： Xin, Zhuo-Hang Chang, Peng-Juan Liu, Zhi-Hong Song, Chang-Chun Department of Hydraulic Engineering Dalian University of Technology Dalian116024 China

The nitrogen flux from terrestrial input is the primary source of nitrogen load in estuarine areas，leading to ecological issues，such as coastal eutrophication and hypoxia. Systematically identifying the nitrogen sources from different rivers draining into the sea is a prerequisite for controlling the nitrogen pollution in estuarine areas. Based on the nitrogen and oxygen isotopes of 179 sampling sites across 12 rivers in Liaoning and Hebei Provinces，the nitrate sources of different rivers were systematically identified. Moreover，the stable isotope analysis in the R（SIAR）model was employed to quantitatively calculate the contribution rates of various pollution sources to river nitrate. The results indicated that nitrification was the primary process of nitrate transformation. For all 12 rivers，the contribution rate of animal manure and sewage ranged from 13.9% to 90.1% and that of soil nitrogen ranged from 4.3% to 54.0%. Additionally，for the Liaojiawa River，Xuanhui River，and Nanpai River in Cangzhou City，agricultural fertilizers were observed to have relatively high contribution rates，ranging from 25.2% to 64.4%. Overall，the nitrogen loads in these 12 rivers were highly disturbed by anthropogenic activities and the primary sources of nitrate varied among different rivers. Therefore implementing targeted and differentiated control measures in watershed nitrogen control and management is important. © 2025 Science Press. All rights reserved.

关键词： Eutrophication

Energy-Efficient D2D-Aided Dual UAV Data Collection

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Chinese Journal of Electronics 2025年第1期34卷 176-185页

作者： Qiulei Huang Wei Wang Zhaohui Song Nan Zhao School of Information and Communication Engineering Dalian University of Technology Space Information Research Institute Hangzhou Dianzi University

Aided by device-to-device(D2D) connections, unmanned aerial vehicle(UAV) can significantly enhance the coverage of wireless communications. In this paper, we consider a data collection system with the assistance of D2D, where two fixed-wing UAVs as aerial base stations cooperatively serve the ground devices. To accommodate more devices, we propose two effective algorithms to establish the multi-hop D2D connections. Then, the user scheduling, UAV trajectory, and transmit power are jointly optimized to maximize the energy efficiency, which is a non-convex problem. Accordingly, we decompose it into three subproblems. The scheduling optimization is first converted into a linear programming. Then, the trajectory design and the transmit power optimization are reformulated as two convex problems by the Dinkelbach method. Finally, an iterative algorithm is proposed to effectively solve the original problem. Simulation results are presented to verify the effectiveness of the proposed scheme.

关键词： Wireless communication Simulation Data collection Autonomous aerial vehicles Linear programming Energy efficiency Trajectory Device-to-device communication Iterative methods Optimization

Performance and electromagnetic mechanism of radar-and infraredcompatible stealth materials based on photonic crystals

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International Journal of Minerals,Metallurgy and Materials 2025年第3期32卷 710-717页

作者： Yanming Liu Xuan Yang Lixin Xuan Weiwei Men Xiao Wu Yuping Duan AVIC Research Institute for Special Structures of Aeronautical Composite Ji’nan 250023China Aviation Key Lab of Science and Technology on High Performance Electromagnetic Windows Ji’nan 250023China Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116085China

Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared ***,they can be detected by various technologies,considerably threatening weapon ***,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic *** radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon *** composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 *** average infrared emissivity of the proposed design is 0.1063,indicating good stealth *** theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared *** stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is *** work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.

关键词： microwave absorption infrared stealth photonic crystal compatible stealth

Electrochemical conversion of methane to bridge the gap in the artificial carbon cycle

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Journal of Energy Chemistry 2025年第1期100卷 286-308页

作者： Yuhao Peng Yuefeng Song Ihar Razanau Juanxiu Xiao Wei Xiao Di Hu Guoxiong Wang College of Chemistry and Molecular Sciences Hubei Key Laboratory of Electrochemical Power SourcesWuhan UniversityWuhan 430072HubeiChina State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyiChEM(Collaborative Innovation Center of Chemistry for Energy Materials)Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Laboratory of Physical-Chemical Technologies SSPA Scientific and Practical Materials Research Centre of NAS of BelarusMinsk 220072Belarus State Key Laboratory of Marine Resources Utilization in South China Sea Collaborative Innovation Center of Marine Science and TechnologySchool of Marine Science and EngineeringHainan UniversityHaikou 570228HainanChina Department of Chemical and Environmental Engineering University of Nottingham Ningbo ChinaNingbo 315100ZhejiangChina

Methane, an abundant one-carbon(C_(1)) resource, is extensively used in the industrial production of vital fuels and value-added chemicals. However, current industrial methane conversion technologies are energy-and carbon-intensive, mainly due to the high activation energy required to break the inert C–H bond, low selectivity, and problematic side reactions, including CO_(2)emissions and coke deposition. Electrochemical conversion of methane(ECM) using intermittent renewable energy offers an attractive solution, due to its modular reactor design and operational flexibility across a broad spectrum of temperatures and pressures. This review emphasizes conversion pathways of methane in various reaction systems, highlighting the significance and advantages of ECM in facilitating a sustainable artificial carbon cycle. This work provides a comprehensive overview of conventional methane activation mechanisms and delineates the complete pathways of methane conversion in electrolysis contexts. Based on surface/interface chemistry, this work systematically analyzes proposed reaction pathways and corresponding strategies to enhance ECM efficiency towards various target products, including syngas, hydrocarbons, oxygenates, and advanced carbon materials. The discussion also encompasses opportunities and challenges for the ECM process, including insights into ECM pathways, rational electrocatalyst design, establishment of benchmarking protocols, electrolyte engineering, enhancement of CH4conversion rates, and minimization of CO_(2)emission.

关键词： Methane Electrochemical conversion Reaction mechanism Catalyst design Electrode Electrocatalysis