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An approach for formation design and flight performance prediction based on aerodynamic formation unit:Energy-saving considerations

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Chinese Journal of Aeronautics 2024年第3期37卷 77-91页

作者： Nanxuan QIAO Tielin MA Xiangsheng wang Jie wang Jingcheng FU Pu XUE School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Institute of Unmanned System Beihang UniversityBeijing 100191China Key Laboratory of Advanced Technology of Intelligent Unmanned Flight System Ministry of Industry and Information TechnologyBeijing 100191China School of Transportation Science and Engineering Beihang UniversityBeijing 102206China Beijing Institute of Space Long March Vehicle Beijing 100076China

The performance improvement of swarm drones through aerodynamic shape optimization may be challenging due to folded size constraints imposed by the specific launch ***,fixed-wing aircraft swarms can benefit from formation flight in terms of energy *** study introduces the concept of the"aerodynamic formation unit",which consists of two or three aircraft that form an inseparable unit of the *** the Unmanned Aerial Vehicle(UAV)distribution and wingtip vortex interference in the formation,two typical aerodynamic formation units are optimized by the variable-fidelity aerodynamic optimization method based on space *** aerodynamic characteristics of the formation UAVs that affect flight performance,such as lift-to-drag ratio(L/D ratio)and static stability are analyzed by Computational Fluid Dynamics(CFD)*** L/D ratio(cruising condition)of the following aircraft can be increased by 22.8%and 57.5%in the optimal units that involve two and three aircraft ***,this study conducts several CFD simulations for multi-aircraft formations formed by the units,which show that the average L/D ratio of the formation can be improved by more than 19%.These results verify the feasibility and effectiveness of the"aerodynamic formation unit"concept and the optimization framework for formation parameters.

关键词： Formation flight CFD Aerodynamic formation unit Wingtip vortices Foldable tandem-wing aircraft

Quantum Chemistry Study on Dissociation of Oxalyl Bromide

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Chinese Journal of Structural Chemistry 2005年第11期24卷 1334-1339页

作者： GENG Zhi-Yuan wang Dong-Mei wang Yong-Cheng DAI Guo-Liang LU Ling-Ling wang Han-Qing College of Chemistry and Chemical Engineering Northwest Normal University Lanzhou 730070 China Lanzhou Institute of Chemistry and Physics The Chinese Academy of Sciences Lanzhou 730000 China Department of Chemistry Baoji College of Arts ＆ Sci. Baoji 721007 China

The multi-bond dissociation dynamics of oxalyl bromide （（BrCO）2） has been investigated by DFT and CIS calculations. Upon the results, conclusion could be drawn that dissociation of C-Br bond of oxalyl bromide at the ground state （So） is of barfierless. After the absorption of a photon, （BrCO）2 is excited to the first excited state and one of its C-Br bonds is broken to yield Br ·＊ and BrCOCO· ＊ free radicals. In addition, BrCOCO · ＊ with high energy is apt to release energy, and ultimately, turns into BrCOCO ·of the ground state. The energy is adequate for BrCOCO· to break down into Br · and 2CO; at the same time the C-C and C-Br bonds of BrCOCO · free radicals dissociate.

关键词： oxalyl bromide multi-bond dissociation BrCOCO free radical DFT

Long-term operation optimization of circulating cooling water systems under fouling conditions

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Chinese Journal of Chemical Engineering 2024年第1期65卷 255-267页

作者： Jiarui Liang Yong Tian Shutong Yang Yong wang Ruiqi Yin Yufei wang School of Chemical Engineering and Environment China University of PetroleumBeijing102249China CHN Energy Xinjiang Chemical Co. LTDUrumqi830092China College of Mechanical and Transportation Engineering China University of PetroleumBeijing 102249China

Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's ***,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering ***,low flow velocity promotes ***,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term *** study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this *** model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and *** optimizing the concentration cycle of the CCWS,water conservation and fouling control can be *** model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance *** experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation *** periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling ***,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.

关键词： Computer simulation Circulating water system Fouling Concentration cycle Optimization Variable frequency drive

Distributed fixed step-size algorithm for dynamic economic dispatch with power flow limits

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Science China(Information Sciences) 2021年第1期64卷 110-122页

作者： Kun wang Zao FU Qian XU Duxin CHEN Lei wang Wenwu YU The State Grid Zhejiang Economic Research Institute School of Cyber Science and Engineering Southeast University School of Mathematics Southeast University

In this study, a discrete-time distributed algorithm is proposed for solving the dynamic economic dispatch problem with active power flow limits and transmission line loss. To avoid the communication burden and implement the algorithm in a favorably distributed manner, the splitting method is used to bypass the centralized updating of the algorithm’s parameters, which is unavoidable when implementing conventional Lagrangian methods. The use of a fixed step-size and distributed update enhances the applicability of the algorithm. The performance and effectiveness of the proposed distributed algorithm are verified via numerical studies on the IEEE 14-bus system.

关键词： dynamic economic dispatch distributed optimization discrete-time algorithm active power flow limit transmission line loss

Edge engineering in chemically active two-dimensional materials

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Nano Research 2022年第11期15卷 9890-9905页

作者： Lijun Zhou Mengyan Li Wei wang Cong wang Huiping Yang Yang Cao State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials(iChEM)College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen UniversityXiamen 361005China

When "cut off" continuous and uniform basal plane of two-dimensional(2D)materials,edges appear at *** edges with unique one-dimensional(1D)structures and bound-states significantly alter materials’local chemical activities and have been extensively investigated as model platforms for investigating structure–property–performance relationships for *** interesting phenomena have been discovered in the past decades,highlighting the importance of interactions between active species and edge atoms at the atomic level and making 1D edges as emerging catalysts with high efficiency,promising candidates for battery and electrochemical ***,this review focuses on the recent progress of edge synthesis and structural engineering methods,understanding of edge structure–activity mechanisms,and potential applications using edge *** and prospects are also envisioned.

关键词： two-dimensional(2D)materials one-dimensional(1D)edges relation of structure-activity

Mo Doping and Electrochemical Activation Co-Induced Vanadium Composite as High-Rate and Long-Life Anode for Ca-Ion Batteries

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Energy & Environmental Materials 2024年第5期7卷 131-139页

作者： Hongchen Pan Chunfang wang Minling Qiu Yaxin wang Cuiping Han Ding Nan College of Chemistry and Chemical Engineering Inner Mongolia University Hohhot 010021China Songshan Lake Materials Laboratory Dongguan523808China The State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Faculty of Materials Science and Engineering/Institute of Technology for Carbon Neutrality Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China

Calcium-ion batteries have been considered attractive candidates for large-scale energy storage applications due to their natural abundance and low redox potential of Ca^(2+)/***,current calcium ion technology is still hampered by the lack of high-capacity and long-life electrode materials to accommodate the large Ca^(2+)(1.00Å).Herein,an amorphous vanadium structure induced by Mo doping and in-situ electrochemical activation is reported as a high-rate anode material for calcium ion *** doping of Mo could destroy the lattice stability of VS4 material,enhancing the flexibility of the *** following electrochemical activation further converted the material into sulfide and oxides co-dominated composite(defined as MoVSO),which serves as an active material for the storage of Ca^(2+)during ***,this amorphous vanadium structure exhibits excellent rate capability,achieving discharge capacities of 306.7 and 149.2 mAh g^(-1)at 5 and 50 A g^(-1)and an ultra-long cycle life of 2000 cycles with 91.2%capacity *** values represent the highest level to date reported for calcium ion *** mechanism studies show that the material undergoes a partial phase transition process to derive *** work unveiled the calcium storage mechanism of vanadium sulfide in aqueous electrolytes and accelerated the development of high-performance aqueous calcium ion batteries.

关键词： calcium-ion batteries electrochemical activation phase transformation vanadium sulfide

Proportional Current Sharing Based on Periodic Dynamic Event-driven H_(∞) Consensus in DC Microgrids with Power Coupling

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1558-1568页

作者： Rui wang Qiuye Sun Lei Liu Li Zhang Peng wang Huaguang Zhang College of Information Science and Engineering Northeastern UniversityLiaoning 110819China College of Science Liaoning University of TechnologyLiaoning 121001China School of Electrical and Electronic Engineering Nanyang Technological University639798Singapore

Although the proportional current sharing has been widely studied,the heterogeneous characteristic of the different interfaced converters and power coupling terms among distributed generators(DGs)are rarely ***,this paper proposes a secondary H_(∞)consensus method with a periodic dynamic event-driven scheme for dc microgrids with power coupling to accomplish the precise proportional *** is useful for reducing ***,a generalized converter is constructed through equivalent transformation between rectifier and boost ***,the heterogeneous characteristic of the interfaced converters regarding different DGs,such as wind and solar generators,is embedded into controller ***,the standard linear heterogeneous multi-agent system with power coupling term is *** this basis,the problem of proportional current sharing is modified into the output consistency problem of multi-agent ***,the H_(∞)consensus approach is proposed to accomplish the precise proportional current ***,to shorten communication bandwidth,the periodic dynamic event-driven communication strategy is *** with traditional event-driven communication schemes,a lower communication frequency has been obtained through the proposed communication *** addition,this communication scheme not only avoids Zeno-behavior,but also acquires the smallest sampling time ***,effectiveness of the proposed approach is verified by two test systems.

关键词： Current sharing event-driven communication H_(∞)consensus approach heterogeneous distributed generators

Deducing the internal interfaces of twisted multilayer graphene via moiré-regulated surface conductivity

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National Science Review 2023年第8期10卷 194-202页

作者： Huan wang Sen wang Shuai Zhang Mengzhen Zhu Wengen Ouyang Qunyang Li Applied Mechanics Laboratory Department of Engineering Mechanics Tsinghua University 2. Department of Engineering Mechanics School of Civil EngineeringWuhan University 3. State Key Laboratory of Water Resources and Hydropower Engineering ScienceWuhan University State Key Laboratory of Tribology in Advanced Equipment Tsinghua University

The stacking state of atomic layers critically determines the physical properties of twisted van der Waals materials. Unfortunately, precise characterization of the stacked interfaces remains a great challenge as they are buried internally. With conductive atomic force microscopy, we show that the moiré superlattice structure formed at the embedded interfaces of small-angle twisted multilayer graphene(tMLG) can noticeably regulate surface conductivity even when the twisted interfaces are 10 atomic layers beneath the surface. Assisted by molecular dynamics(MD) simulations, a theoretical model is proposed to correlate surface conductivity with the sequential stacking state of the graphene layers of tMLG. The theoretical model is then employed to extract the complex structure of a tMLG sample with crystalline defects. Probing and visualizing the internal stacking structures of twisted layered materials is essential for understanding their unique physical properties, and our work offers a powerful tool for this via simple surface conductivity mapping.

关键词： twisted graphene electrical conductivity embedded interface atomic reconstruction moiré pattern

CO_(2)hydrogenation to methanol promoted by Cu and metastable tetragonal Ce_(x)Zr_(y)O_(z) interface

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Journal of Energy Chemistry 2022年第5期31卷 771-779页

作者： Na Li Weiwei wang Lixin Song Hui wang Qiang Fu Zhenping Qu Key Laboratory of Industrial Ecology and Environmental Engineering School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024LiaoningChina State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina

Designing effective catalyst to improve the activity of CO_(2) hydrogenation to methanol is a potential avenue to realize the utilization of CO_(2) resources. Herein we construct three kinds of Cu/Ce_(x)Zr_(y)O_(z)(CCZ) catalysts with different crystal phases of Ce_(x)Zr_(y)O_(z)solid solutions, which demonstrate distinct activity and methanol selectivity in the order of metastable tetragonal-CCZ(CCZ-t’’, parts of oxygen in Ce_(x)Zr_(y)O_(z) were replaced by tetragonal phase from cubic fluorite phase) > tetragonal-CCZ(CCZ-t) > cubic-CCZ(CCZ-c) for CO_(2) hydrogenation to methanol. Structural analysis reveals that oxygen vacancies, surface hydroxyls and unsaturated Cu species of CCZ all follow the same sequence as that of activity and methanol selectivity,indicating that the above features are beneficial to improve the catalytic reaction *** programmed experiments and mechanism studies show that the interface between Cu and tetragonal(t and t’’) Ce_(x)Zr_(y)O_(z) can promote CO_(2) adsorption, and the adsorbed CO_(2) is more reactive and can generate active bidentate carbonate species, which can be hydrogenated to form active monodentate and bidentate formate species under CO_(2) and H_(2) atmosphere. These intermediates should be crucial to the formation of methanol product. CCZ-t’’has stronger H_(2) activation ability than CCZ-t, which makes the former catalyst have more intermediates and higher methanol selectivity. In contrast, CO_(2) mainly adsorbs on cubic Ce_(x)Zr_(y)O_(z) support of CCZ-c, but its H_(2) spillover ability is low, which hinders the reaction process. In addition, the strong adsorption of surface intermediates on CCZ-c is also not conducive to methanol formation. Results here demonstrate that constructing active Cu-support interfaces may be an important approach to design effective catalyst for CO_(2)hydrogenation.

关键词： CO_(2)hydrogenation Methanol Copper Cerium zirconium solid solution Interface