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Proof of Ding’s Conjecture on Maximal Stable Sets and Maximal Cliques in Planar Graphs

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Acta Mathematicae Applicatae Sinica 2010年第3期26卷 473-480页

作者： Jing Sun zhi-quan hu Faculty of Mathematics and Statistics Central China Normal University Wuhan 430079 China School of Mathematics and Quantitative Economics Hubei University of Education Wuhan 430205 China

X. Deng et al. proved Chvātal＇s conjecture on maximal stable sets and maximal cliques in graphs. G. Ding made a conjecture to generalize Chvátal＇s conjecture. The purpose of this paper is to prove this conjecture ... 详细信息

关键词： Maximal stable set maximal clique planar graph

Sb^(3+)and Sm^(3+)co-doped lead-free Cs_(2)NaInCl_(6)double perovskite nanocrystals for single-component cold white emitter

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Journal of Rare Earths 2024年第9期42卷 1646-1651,I0001页

作者： biao Zhou Xiangtong Zhang Ranran hu Ruixue Hou William W.Yu Key Laboratory for Special Functional Materials of Ministry of Education National&Local Joint Engineering Research Centre for High-Efficiency Display and Lighting TechnologySchool of Materials and EngineeringCollaborative Innovation Centre of Nano Functional Materials and ApplicationsHenan UniversityKaifeng475000China School of Chemistry and Chemical Engineering Shandong UniversityJinan250100China

Metal halide perovskites exhibit promising prospect in light-emitting diodes,solar cells,photodetectors and ***,the workhorse of metal halide perovskites relies on toxicity lead element,which severely damages human body and *** lead-free perovskites,Cs_(2)NaInCl_(6)double perovskite is one of the most promising candidates because of its great stability and easy synthesis,but suffers inadequate optical ***,we doped Sb^(3+)and Sm^(3+)into Cs_(2)NaInCl_(6)nanocrystals by a hot injection ***_(2)NaInCl_(6):Sb^(3+)exhibits blue emission at 447 ***_(2)NaInCl_(6):Sm^(3+),Sb^(3+)nanocrystals simultaneously generate the blue emission of Sb^(3+)and the multiple emissions of Sm^(3+)at 565,602,650 and 710 *** the increase of Sm^(3+)feed ratio,the emission color of Cs_(2)NaInCl_(6):Sm^(3+),Sb^(3+)gradually moves to cold white region at(0.27,0.28)in CIE chromaticity diagram and correlated color temperature of 11840 *** work shows the potential application of Cs_(2)NaInCl_(6):Sm^(3+),Sb^(3+)nanocrystals as a single-component cold white emitter.

关键词： Lead-free Double perovskites Single component White emitter Doping Rare earths

One-pot Synthesis of Dimethyl Carbonate in the Presence of a Two-component Catalyst

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Chemical Research in Chinese Universities 2005年第6期21卷 714-717页

作者： CHEN Xiu-zhi hu Chang-wen GAO zhi-ming The Institute for Chemical Physics Beijing Institute of Technology Beijing 100081 P. R. China Department of Chemistry Beijing Institute of Technology Beijing 100081 P. R. China

The one-pot synthesis of dimethyl carbonate（DMC） with co-production of propy-lene carbonate（PC） and propylene glycol（PG） from propylene oxide（ PO）, carbon dioxide and methanol as the starting materials was investigated. The catalyst adopted here was a mixture of tetrabutyl ammonium bromide and sodium methoxide. It was found that un- der the reaction conditions of t = 150 ℃, p =3-4 MPa and 2 h, the PO conversion could reach 100%, the DMC, PC and the PG selectivities were 49. 7%, 42. 7% and 49. 8%, respectively, and the selectivity of by-products was below 10%.

关键词： Dimethyl carbonate Carbon dioxide Propylene oxide Propylene carbonate Catalyst

Hairy Root and Its Application in Plant Genetic Engineering

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Journal of Integrative Plant Biology 2006年第2期48卷 121-127页

作者： zhi-Bi hu Min Du Institute of Chinese Materia Medica Shanghai University of Traditional Chinese Medicine Shanghai 201203 China

Agrobacterium rhizogenes Conn. causes hairy root disease In plants. Hairy root-Infected A. rhizogenes Is characterlzed by a high growth rate and genetic stability. Hairy root cultures have been proven to be an efficient means of producing secondary metabolites that are normally biosyntheslzed In roots of differentiated plants. Furthermore, a transgenlc root system offers tremendous potential for introducing additional genes along with the RI plasmld, especially with modified genes, into medicinal plant cells with A. rhizogenes vector systems. The cultures have turned out to be a valuable tool with which to study the biochemical properties and the gene expression profile of metabolic pathways. Moreover, the cultures can be used to elucidate the Intermediates and key enzymes Involved In the biosynthesis of secondary metabolites. The present article discusses various appllcations of hairy root cultures in plant genetic engineering and potential problems aseoclsted with them.

关键词： Agrobacterium rhizogenes hairy root plant genetic engineering Ri plasmid secondary metabolites.

Near-perfect replication on amorphous alloys through active force modulation based on machine learning/neural network parameter prediction

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 181-191页

作者： Senkuan Meng Zheng Wang Ruisong Zhu Ruijie Liu Jiang Ma Lina hu Weihua Wang Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education) School of Materials Science and Engineering Shandong University College of Mechatronics and Control Engineering Shenzhen University Songshan Lake Materials Laboratory Institute of Physics Chinese Academy of Sciences

As a microforming technique, micro/nano-structural replication possesses advantages of high precision and efficiency. With the remarkable superplasticity in the supercooled liquid region, amorphous alloys or metallic glasses(MGs) are regarded as ideal materials for miniature fabrication. However, due to the intrinsic metastable nature of supercooled liquids, the design of imprinting processes for MGs poses a challenge. In the past, process parameters have largely relied on trial-and-error *** this work, a low-frequency active force modulation system is employed to apply a stable, precise, and real-time feedback stress field for imprinting of MG samples. Low-frequency vibrations can facilitate the filling of microstructures on the template surface by reducing the effective viscosity of the supercooled liquid. With the dataset composed of orthogonal experiments, a machine learning strategy based on back-propagation(BP) neural networks was utilized to construct a 3D parameter space for temperature, stress, and time, and to predict the corresponding filling ratio. Furthermore, the optimal combination of imprinting process parameters was identified, and its filling ratio was experimentally validated to reach as high as 0.94. The near-perfect replication of microstructures confirms the superiority of the active force modulation system and the data-driven strategy of machine learning-assisted parameter design. At the same time, this one-step microforming process provides a new approach to addressing the accuracy-cost trade-off dilemma in precision manufacturing.

关键词： metallic glass amorphous alloy microforming imprinting machine learning

One-step synthesis and electromagnetic absorption properties of high entropy rare earth hexaborides(HE REB6)and high entropy rare earth hexaborides/borates(HE REB6/HE REB03)composite powders

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Journal of Advanced Ceramics 2021年第1期10卷 62-77页

作者： Weiming ZHANG biao ZHAO huimin XIANG Fu-zhi DAI Shijiang WU Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Henan Key Laboratory of Aeronautical Materials and Application Technology School of Material Science and EngineeringZhengzhou University of AeronauticsZhengzhou 450046China Zibo Firststar New Material Incorporated Co. Ltd.Zibo 255000China

Considering the emergence of severe electromagnetic interference problems,it is vital to develop electromagnetic(EM)wave absorbing materials with high dielectric,magnetic loss and optimized impedance ***,realizing the synergistic dielectric and magnetic losses in a single phase material is still a ***,high entropy(HE)rare earth hexaborides(REB6)powders with coupling of dielectric and magnetic losses were designed and successfully synthesized through a facial one-step boron carbide reduction method,and the effects of high entropy borates intermedia phases on the EM wave absorption properties were *** HE REB6 ceramics including(Ce0.2Y0.2Sm0.2Er0.2Yb0.2)B6,(Ce0.2hu0.2Sm0.2Er0.2Yb0.2)B6,(Ce0.2Y0.2Eu0.2Er0.2Yb0.2)B6,(Ce0.2Ya2Sm0.2Eu0.2Yb0.2)B6,and(Nd0.2Y0.2Sm0.2Eu0.2Yb0.2)B6 possess CsCl-type cubic crystal structure,and their theoretical densities range from 4.84 to 5.25 g/cm^(3).(Ce02Y0.2Sm0.2Er0.2Yb02)B6 powders with the average particle size of 1.86 jim were found to possess the best EM wave absorption properties among these *** RLmin value of(Ce0.2Y0.2Sm0.2Er0.2Yb0.2)B6 reaches-33.4 dB at 11.5 GHz at thickness of 2 mm;meanwhile,the optimized effective absorption bandwidth(EAB)is 3.9 GHz from 13.6 to 17.5 GHz with a thickness of 1.5 *** introduction of HE REB03(RE=Ce,Y,Sm,Eu,Er,Yb)as intermediate phase will give rise to the mismatching impedance,which will further lead to the reduction of reflection ***,the HEREB6/HEREB03 still possess wide effective absorption bandwidth of 4.1 GHz with the relative low thickness of 1.7 *** the better stability,low density,and good EM wave absorption properties,HE REB6 ceramics are promising as a new type of EM wave absorbing materials.

关键词： high entropy rare earth hexaborides(HE REB6) one-step synthesis electromagnetic wave absorbing properties synergistic dielectric and magnetic losses wide effective absorption bandwidth

Safe Efficient Policy Optimization Algorithm for Unsignalized Intersection Navigation

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 2011-2026页

作者： Xiaolong Chen biao Xu Manjiang hu Yougang Bian Yang Li Xin Xu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082 Wuxi Intelligent Control Research Institute(WICRI)of hunan University Wuxi 214115China College of Intelligence Science and Technology Institute of Unmanned SystemsNational University of Defense TechnologyChangsha 410073China

Unsignalized intersections pose a challenge for autonomous vehicles that must decide how to navigate them safely and *** paper proposes a reinforcement learning(RL)method for autonomous vehicles to navigate unsignalized intersections safely and *** method uses a semantic scene representation to handle variable numbers of vehicles and a universal reward function to facilitate stable learning.A collision risk function is designed to penalize unsafe actions and guide the agent to avoid them.A scalable policy optimization algorithm is introduced to improve data efficiency and safety for vehicle learning at *** algorithm employs experience replay to overcome the on-policy limitation of proximal policy optimization and incorporates the collision risk constraint into the policy optimization *** proposed safe RL algorithm can balance the trade-off between vehicle traffic safety and policy learning *** intersection scenarios with different traffic situations are used to test the algorithm and demonstrate its high success rates and low collision rates under different traffic *** algorithm shows the potential of RL for enhancing the safety and reliability of autonomous driving systems at unsignalized intersections.

关键词： Autonomous driving decision-making reinforcement learning(RL) unsignalized intersection

Comparative review of corrosion-resistant coatings on metal bipolar plates of proton exchange membrane fuel cells

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International Journal of Minerals,Metallurgy and Materials 2024年第12期31卷 2627-2644页

作者： Jiaming Liu Qian hu Sandrick Sabola Yue Zhang biao Du Xianzong Wang Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Coal Chemical Industry Technology Research Institute Co. Ltd.Xi’an 710065China

In the realm of proton exchange membrane fuel cells(PEMFCs),the bipolar plates(BPs)are indispensable and serve pivotal roles in distributing reactant gases,collecting current,facilitating product water removal,and cooling the *** BPs,characterized by outstanding manufacturability,cost-effectiveness,higher power density,and mechanical strength,are emerging as viable alternatives to traditional graphite *** foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions,necessitating the application of various coatings on their surfaces to ensure superior *** review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs,including noble metal,carbide,ni-tride,and amorphous carbon(a-C)/metal compound composite *** various challenges encountered in the manufacturing and fu-ture application of these coatings are also delineated.

关键词： proton exchange membrane fuel cells metallic bipolar plate coatings corrosion resistance interfacial contact resistance

Study on wave dispersion characteristics of piezoelectric sandwich nanoplates considering surface effects

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Applied Mathematics and Mechanics(English Edition) 2022年第9期43卷 1339-1354页

作者： biao hu Juan LIU Yuxing WANG Bo ZHANG Jing WANG huoming SHEN Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China School of Mechanical and Electrical Engineering Southwest Petroleum UniversityChengdu 610500China

In this study,the wave propagation properties of piezoelectric sandwich nanoplates deposited on an orthotropic viscoelastic foundation are analyzed by considering the surface effects(SEs).The nanoplates are composed of a composite layer reinforced by graphene and two piezoelectric surface *** the modified Halpin-Tsai model,the material parameters of composite layers are *** displacement field is determined by the sinusoidal shear deformation theory(SSDT).The Euler-Lagrange equation is derived by employing Hamilton’s principle and the constitutive equations of piezoelectric layers considering the ***,the nonlocal strain gradient theory(NSGT)is used to obtain the equations of ***,the effects of scale parameters,graphene distribution,orthotropic viscoelastic foundation,and SEs on the propagation behavior are numerically *** results reveal that the wave frequency is a periodic function of the orthotropic ***,the wave frequency increases with the increase in the SEs.

关键词： surface effect(SE) scale parameters orthotropic foundation functional gradient graphene piezoelectric sandwich nanoplate