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On the Generalized Geroch Conjecture for Complete Spin Manifolds

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Chinese Annals of Mathematics,Series B 2022年第6期43卷 1143-1146页

作者： xiangsheng wang Weiping ZHANG School of Mathematics Shandong UniversityJinan 250100China Chern Institute of Mathematics&LPMC Nankai UniversityTianjin 300071China.

Let W be a closed area enlargeable manifold in the sense of Gromov-Lawson and M be a noncompact spin manifold,the authors show that the connected sum M#W admits no complete metric of positive scalar *** W=T^(n),this p... 详细信息

关键词： Positive scalar curvature Connected sum Spin manifolds

Spectral flow, Llarull's rigidity theorem in odd dimensions and its generalization

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Science China Mathematics 2024年第5期67卷 1103-1114页

作者： Yihan Li Guangxiang Su xiangsheng wang Chern Institute of Mathematics&LPMC Nankai UniversityTianjin 300071China School of Mathematics Shandong UniversityJinan 250100China

For a compact spin Riemannian manifold(M,g^(TM))of dimension n such that the associated scalar curvature kT M verifies that k^(TM)≥n(n-1),Llarull’s rigidity theorem says that any area-decreasing smooth map f from M to the unit sphere Sn of nonzero degree is an *** this paper,we present a new proof of Llarull’s rigidity theorem in odd dimensions via a spectral flow *** approach also works for a generalization of Llarull’s theorem when the sphere Sn is replaced by an arbitrary smooth strictly convex closed hypersurface in Rn+*** results answer two questions by Gromov(2023).

关键词： Dirac operator scalar curvature spectral flow

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

Methane aromatization in the absence of oxygen over extruded and molded MoO_3/ZSM-5 catalysts:Influences of binder and molding method

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Journal of Natural Gas Chemistry 2010年第6期19卷 646-652页

作者： Dongmei Ren xiangsheng wang Gang Li Xiaojing Cheng Huayun Long Lidong Chen State Key Laboratory of Fine Chemicals Dalian University of Technology Department of Catalytical Chemistry and Engineering Dalian 116012 Liaoning China Faculty of Chemistry and Chemical Engineering Bohai University Jinzhou 121000 Liaoning China School of Chemistry and Chemical Engineering Xinjiang University Urumqi 830046 Xinjiang China

The influences of binder and molding method on the catalytic performance of methane aromatization in the absence of O2 over MoO3/ZSM-5 catalysts were ***,NH3-TPD,FT-IR of adsorbed pyridine,N2 adsorption-desorption,cyclohexane adsorption and XPS were employed to characterize the physical and chemical properties of the *** was found that SiO2 was a suitable binder for the catalyst due to its appropriate weak *** laminar catalyst comprising of an inert spherical core and a MoO3/ZSM-5 laminar shell with 0.1 0.2 mm in thickness showed a better catalytic performance than the extruded *** improved activity of the laminar catalyst could be attributed to the easy carbonization of Mo species and the quick removal of reaction products from the catalyst surface.

关键词： methane aromatization extruded catalyst laminar catalyst ZSM-5 molybdenum

Quick Synthesis of Titanium Silicalite-1

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催化学报 2001年第6期22卷 513-514页

作者： wang Liqin wang xiangsheng GUO Xinwen LI Gang XIU Jinghai State Key Laboratory of Fine Chemicals Dalian University of TechnologyDalian 116012China Department of Chemical Engineering Qiqihar UniversityQiqihar 161006China

quick synthesis, titanium silicalite-1, anatase titania, propylene, epoxidation, hydrogen peroxide

关键词：钛硅分子筛 TS-1 催化剂合成催化性能