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Totally geodesic submanifolds of maximal rank in symmetric spaces

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Science china Mathematics 2004年第2期47卷 264-271页

作者： ZHU Fuhai & liang Keschool of mathematical sciences and lmam, peking university, beijing 100871, china College of mathematical sciences and LPMC, Nankai university, Tianjin 300071, china 1.school of mathematical sciences and lmam Peking University 100871 Beijing China 2.College of Mathematical Sciences and LPMC Nankai University 300071 Tianjin China

We gave a complete list of totally geodesic submanifolds of maximal rank in symmetric spaces of noncompact type. The compact cases can be obtained by the duality.

关键词： totally geodesic submanifold, Lie triple system, maximal rank.

The Faber Operator Acting on BMOA, BMO-Teichmüller Space and Chord-arc Curves

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Acta Mathematica Sinica,English Series 2024年第10期40卷 2359-2387页

作者： Tai liang LIU Yu liang shen Department of Mathematics Soochow University

After reviewing Grunsky operator and Faber operator acting on Dirichlet space, we discuss the boundedness of Faber operator on BMOA, a new subject which turns out to be closely related to the BMO theory of the universal Teichmüller space. In particular, we show that the Faber operator acts as a bounded operator on BMOA if the symbol conformal map stays nearly to the base point in the BMO-Teichmüller space. Meanwhile, we obtain several results on quasiconformal mappings, BMOTeichm¨uller space and chord-arc curves as well. As by-products, this provides a complex analysis approach to the boundedness of the Cauchy integral acting on BMO functions on a chord-arc curve near to the unit circle in the BMO-Teichmüller space.

关键词： 30C62 30H35 32G15 BMO BMO-Teichmüller space BMOA Carleson measure Cauchy integral chord-arc curve Faber operator Grunsky operator quasicircle quasiconformal mapping

Some constructions of projectively flat Finsler metrics

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Science china Mathematics 2006年第5期49卷 703-714页

作者： MO Xiaohuan, shen Zhongmin & YANG Chunhong lmam, school of mathematical sciences, peking university, beijing 100871, china Department of mathematical sciences, Indiana university-Purdue university, Indianapolis, IN 46202-3216, USA Department of Mathematics, Inner Mongolia university, Hohhot 010021, china lmam School of Mathematical Sciences Peking University Beijing 100871 China Department of mathematical sciences Indiana University-Purdue University Indianapolis IN 46202-3216 USA Department of Mathematics Inner Mongolia University Hohhot 010021 China

In this paper, we find some solutions to a system of partial differential equations that characterize the projectively flat Finsler metrics. Further, we discover that some of these metrics actually have the zero flag ... 详细信息

关键词： Randers metric, (α,β)-metric, Finsler metric, projectively flat metric, Scurvature.

CMOS-level mega-pixel organic camera chips made of photocrosslinked photovoltaic nanocells

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Science china Materials 2024年第9期67卷 3043-3045页

作者： Yegang liang Zhuoran Wang Guozhen shen school of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing100081China

Organic and hybrid optoelectronics have been driving the frontiers in displays,sensing,and energy in recent decades due to their superior performance,low-cost high-yield manufacturing,and new form factor of mechanical flexibility that is promising for lightweight and wearable applications[1-3].However,the inherent vulnerability makes organic semiconductors incompatible with conventional semiconductor microfabrication,posing significant challenges in high density integration to compete with the resolution of conventional image sensors[4].

关键词： frontier driving lightweight

Recent progress of cobalt-based electrocatalysts for water splitting: Electron modulation, surface reconstitution, and applications

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Nano Research 2024年第4期17卷 2234-2269页

作者： Zhijian liang Di shen Lei Wang Honggang Fu Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education of the People’s Republic of ChinaHeilongjiang UniversityHarbin 150080China

Electrocatalytic water splitting is an essential and effective means to produce green hydrogen energy structures,so it is necessary to develop non-precious metal catalysts to replace precious ***-based catalysts present effective alternatives due to the diverse valence states,adjustable electronic structures,and plentiful *** this review,the catalytic mechanisms of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)for electrocatalytic water splitting are ***,the synthesis strategies of various cobalt-based catalysts are systematically summarized,followed by the relationships between the structure and performance ***,the effects of d-band center and spin regulation for cobalt-based catalysts are also ***,the dynamic electronic and structural devolution of cobalt-based catalysts are elucidated by combining a series of in-situ ***,we highlight the challenges and future developed directions of cobalt-based catalysts for electrocatalytic water splitting.

关键词： cobalt-based electrocatalysts water splitting electron modulation surface reconfiguration

Aggregation-regulated bioreduction process of graphene oxide by Shewanella bacteria

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Chinese Journal of Chemical Engineering 2024年第5期69卷 56-62页

作者： Kaixin Han Yibo Zeng Yinghua Lu Ping Zeng liang shen Department of Chemical and Biochemical Engineering College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen UniversityXiamen 361005China Chinese Research Academy of Environmental sciences Beijing 100012China

The bioreduction of graphene oxide(GO)using environmentally functional bacteria such as Shewanella represents a green approach to produce reduced graphene oxide(rGO).This process differs from the chemical reduction that involves instantaneous molecular *** bioreduction,the contact of bacterial cells and GO is considered the rate-limiting *** reveal how the bacteria-GO integration regulates rGO production,the comparative experiments of GO and three Shewanella strains were carried ***-transform infrared spectroscopy,X-ray photoelectron spectroscopy,Raman spectroscopy,and atomic force microscopy were used to characterize the reduction degree and the aggregation *** results showed that a spontaneous aggregation of GO and Shewanella into the condensed entity occurred within 36 h.A positive linear correlation was established,linking three indexes of the aggregation potential,the bacterial reduction ability,and the reduction degree(ID/IG)comprehensively.

关键词： Graphene oxide Reduced graphene oxide Bioreduction Aggregation Shewanella

Two Parameter Smooth Martingales on the Wiener Space

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Acta Mathematica Sinica,English Series 1997年第2期13卷 239-246页

作者： liang Zongxia (school of mathematical Science,peking university,beijing 100871,china) school of mathematical Science Peking University

We prove that two parameter smooth continuous martingales have ∞-modification and establish a Doob’s inequality in terms of(p,r)-capacity for two parameter smooth martingales.

关键词： Two parameter smooth martingales ∞-modifications Doob’s inequality (p,r)-capacity

Ride-hailing origin-destination demand prediction with spatiotemporal information fusion

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Transportation Safety and Environment 2024年第2期6卷 63-74页

作者： Ning Wang liang Zheng Huitao shen Shukai Li school of Traffic and Transportation Engineering Central South UniversityChangsha 410075China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong UniversityBeijing 100044China

Accurate demand forecasting for online ride-hailing contributes to balancing traffic supply and demand,and improving the service level of ride-hailing *** contrast to previous studies,which have primarily focused on the inflow or outflow demands of each zone,this study proposes a conditional generative adversarial network with a Wasserstein divergence objective(CWGAN-div)to predict ride-hailing origin-destination(OD)demand *** blocks and refined loss functions help to enhance the stability of model *** conditional information is employed to capture external spatiotemporal dependencies and guide the model towards generating more precise *** analysis using ride-hailing data from Manhattan,New York City,demon-strates that our proposed CWGAN-div model can effectively predict the network-wide OD matrix and exhibits strong convergence *** experiments also show that the CWGAN-div outperforms other benchmarking ***,the proposed model displays potential for network-wide ride-hailing OD demand prediction.

关键词： intelligent transport system ride-hailing generative adversarial networks spatiotemporal dependencies origin-destination(OD)demand prediction

Enhanced Flexoelectricity in Barium Titanate-Cellulose Composite Thin Films

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Acta Mechanica Solida Sinica 2024年第4期37卷 521-527页

作者： Wensi Xing Hongyu Cao Xin Zhang Xu liang Jianwei Song shengping shen Chemomechanics and Intelligent Media Laboratory State Key Laboratory for Strength and Vibration of Mechanical StructuresSchool of Aerospace EngineeringXi’an Jiaotong UniversityXi’an710049China

Biopolymers,the potential flexoelectric materials,are environment-friendly,degradable,lightweight,cost-effective,and possess remarkable processing properties catering to the requirements of advanced ***,the flexoelectric coefficient of biopolymers is normally much weaker than that of ceramic materials,limiting their potential applications for designing high-performance green electromechanical coupling *** improve the flexoelectric response in biopolymers,we composited barium titanate(BTO)with 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibrils(TOCNF)to enhance the flexoelectric response of *** to the high permittivity and flexoelectric effect of BTO,the relative dielectric constant and flexoelectric coefficient of 33.3 wt%BTO-TOCNF films reached 30.94@1 kHz and 50.05±1.88 nC/m@1 Hz,which were almost 172 times and 27 times higher than those of TOCNF,*** composite thin film contains high dielectric constant and flexoelectric coefficient,as well as excellent *** study provided a straightforward and efficient method for improving the flexoelectric effect of biopolymers,and demonstrated its great potential applications in flexoelectric-based devices.

关键词： Flexoelectricity Cellulose BaTiO_(3) Composite Thin films