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Existence of Positive Solutions to a Fractional-Kirchhoff System

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 225-240页

作者： Peng-fei Li Jun-hui Xie Dan Mu School of Mathematics and Statistics Hubei Minzu UniversityEnshi445000China

LetΩbe a bounded smooth domain in RN(N≥3).Assuming that 00 are constants,we consider the existence results for positive solutions of a class of fractional elliptic system below,{(a+b[u]^(2)_(s))(-Δ)^(s)u=vp+h_(1)(x,u,v,▽u,▽v),x∈Ω,(-Δ)^(s)v=u^(q)+h_(2)(x,u,▽,▽u,▽v),x∈Q,u,v>0,x∈Ω,u=v=0,x∈RN\Ω.Under some assumptions of hi(x,u,v,▽u,▽v)(i=1,2),we get a priori bounds of the positive solutions to the problem(1.1)by the blow-up methods and rescaling *** on these estimates and degree theory,we establish the existence of positive solutions to problem(1.1).

关键词： fractional-Kirchhoff system a priori bounds degree theory positive solution

Insights into the provenance implication of leaf wax n-alkanes along the lower yellow River

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Science China Earth Sciences 2024年第6期67卷 2001-2018页

作者： Liang ZHANG Jinzhao LIU Chong JIANG fei ZHANG Zhisheng AN School of Human Settlements and Civil Engineering Xi’an Jiaotong UniversityXi’an 710054China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China National Observation and Research Station of Earth Critical Zone on the Loess Plateau of Shaanxi Xi’an 710061China

Serving as one of the largest rivers in terms of both sediment and organic carbon transport fluxes in the world,the yellow River plays a crucial role in regional biogeochemical process as well as in the global carbon ***,although a large number of studies have been carried out on the flux,composition,source and seasonal variation of total particulate organic carbon in the yellow River so far,studies on molecular biomarkers at different spatial and temporal scales are still *** this study,we focus on the molecular and hydrogen isotopic properties of leaf wax n-alkanes among different types of samples which obtained from different seasons(flood ***-flood)along the lower yellow *** molecular distribution of n-alkanes show that the riparian topsoils are subject to inputs from the overly.ng vegetation,while the suspended sediments from the flood season are characterized by the mixing of soil materials which originate from various stratigraphy with different ages on the Chinese Loess *** to the contrasting hydrodynamic conditions,the n-alkanes in suspended sediments also show distinct molecular composition between flood and non-flood ***,considering the effect of climatic factors,the proportion of monocots in flood-season suspended sediments is calculated from a semi-quantitative perspective using δ^(2)H_(wax).Our findings may bring to light new considerations for the interpretation of leaf wax proxies in studies of organic matter sources of yellow River.

关键词： Molecular distribution Hydrogen isotopic composition Leaf wax n-alkanes Suspended sediments Lower yellow River

Lumbar and neck injuries of occupants in different reclining postures

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Chinese Journal of Traumatology 2024年第4期27卷 211-217页

作者： Di-yi Liu Sen Xiao fei-fei Han Bo-Tao Hu School of Mechanical Engineering Hebei University of TechnologyTianjin300131China CATARC(Tianjin) Automotive Engineering Research Institute Co.Ltd.Tianjin300399China

Purpose:With the increasing level of automation in automobiles,the advent of autonomous vehicles hasreduced the tendency of drivers and passengers to focus on the task of *** increasing automation in automobiles reduced the drivers'and passengers'focus on driving,which allowed occupants tochoose a more relaxed and comfortable sitting ***,the occupant's sitting position wentfrom a frontal,upright position to a more relaxed and reclined one,which resulted in the existing restraint systems cannot to keep occupants safe and *** study aimed to determine the effects ofdifferent reclining states on occupants'lumbar and neck ***:This is an original research on the field of automotive safety *** indifferent initial sitting positions(25°,35°,45°,and 55°)were adapted to changes in seat back angle andrestraint systems and placed in the same frontal impact *** injury indexes,lumbar axialcompression force and acceleration,as well as occupant dynamic response during the impact,werecompared in different sitting *** injury response and kinematic characteristics of occupants indifferent reclining positions were analy.ed by the control variable ***:As the sitting angle increased,the occupant's head acceleration decreased,and the forward-leanangle *** in the standard sitting position had the greatest neck injury,with an Nij of0.95,and were susceptible to abbreviated injury scale 2+cervical medullary *** the seatbackangle increased,the geometric position of the lumbar spine tended to be horizontal,and the impact loadtransmitted greater forces to the lumbar *** occupant's lumbar injury was greatest in the ly.ngposition,with a peak axial compression force on the lumbar region of 5.5 KN,which was 2.3 KN greaterthan in the standard sitting ***:The study of occupant lumbar and neck injuries based on different recline states can providea theoretical bas

关键词： Frontal impact Recline position Lumbar injury Neck injury Kinematics Road traffic injury Road safety

Enhancing adhesive bond strength of CFRP/titanium joints through NaOH anodising and resin pre-coating treatments with optimised anodising conditions

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Chinese Journal of Aeronautics 2024年第2期37卷 511-523页

作者： yunsen HU Jingheng ZHANG Lin WANG fei CHENG Xiaozhi HU School of Materials and Chemistry Southwest University of Science and TechnologyMianyang 621000China School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China Engineering Research Center of Biomass Materials Ministry of EducationSouthwest University of Science and TechnologyMianyang 621010China Department of Mechanical Engineering University of Western AustraliaPerthWA 6009Australia

Adhesively.Bonded Carbon Fibre Reinforced Plastic(CFRP)and titanium alloy have been extensively.used as a hybrid structure in modern aircrafts due to their excellent combination of mechanical properties and chemical *** study utilised NaOH anodising method to create micro-rough titanium surfaces for enhancing adhesive bonding between titanium alloy and CFRP laminates.A special and simple technique named Resin Pre-Coating(RPC)was also employed to improve the surface wetting of anodised titanium and grinded CFRP *** influences of anodising temperature and duration on the surface morphology,wettability and adhesive bond strength were *** single lap shear test results showed that the bond strength of specimens anodised at 20℃for 15 min improved by 135.9%and 95.4%,respectively.in comparison with that of acid pickled and grinded specimens(without RPC treatment).Although increasing the anodising temperature and duration produced rougher titanium surfaces,the adhesively.bonded joints were not strong enough due to relatively.friable titanium oxide layers.

关键词： Carbon Fibre Reinforced Poly.er(CFRP) Titanium alloy Anodising Resin pre-coating Adhesive joints

A Hybrid Integrated and Low-Cost Multi-Chip Broadband Doherty Power Amplifier Module for 5G Massive MIMO Application

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Engineering 2024年第7期38卷 223-232页

作者： fei Huang Guansheng Lv Huibo Wu Wenhua Chen Zhenghe Feng Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-input multiple-output(MIMO)*** inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small *** proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 *** gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3%with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 *** measured adjacent channel power ratio(ACPR)is better than50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.

关键词： 5G Doherty power amplifier Multi-input multi-output Multi-chip modules Hybrid integrated

A CSMA/CA based MAC protocol for hybrid Power-line/Visible-light communication networks:Design and analy.is

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Digital Communications and Networks 2024年第2期10卷 481-497页

作者： Sheng Hao Huyin Zhang fei yang Chenghao Li Jing Wang School of Computer Science Central China Normal UniversityWuhan430079PR China Hubei Key Laboratory of intelligent Robot(Wuhan Institute of Technology) Wuhan430079PR China School of Computer Science Wuhan UniversityWuhan430079China School of Information Science and Engineering Shandong Normal UniversityJinan250000China School of Computer Science Hubei University of TechnologyWuhan430079China

Hybrid Power-line/Visible-light Communication(HPVC)network has been one of the most promising Cooperative Communication(CC)technologies for constructing Smart Home due to its superior communication reliability and hardware *** research on HPVC networks focuses on the performance analy.is and optimization of the Physical(PHy)layer,where the Power Line Communication(PLC)component only.serves as the backbone to provide power to light Emitting Diode(LED)*** designing a Media Access Control(MAC)protocol remains a great challenge because it allows both PLC and Visible Light Communication(VLC)components to operate data transmission,i.e.,to achieve a true HPVC network *** solve this problem,we propose a new HPC network MAC protocol(HPVC MAC)based on Carrier Sense Multiple Access/Collision Avoidance(CSMA/CA)by combining IEEE 802.15.7 and IEEE 1901 ***,we add an Additional Assistance(AA)layer to provide the channel selection strategies for sensor stations,so that they can complete data transmission on the selected channel via the specified CSMA/CA mechanism,*** on this,we give a detailed working principle of the HPVC MAC,followed by the construction of a joint analy.ical model for mathematicalmathematical validation of the HPVC *** the modeling process,the impacts of PHy layer settings(including channel fading types and additive noise feature),CSMA/CA mechanisms of 802.15.7 and 1901,and practical configurations(such as traffic rate,transit buffer size)are comprehensively.taken into ***,we prove the proposed analy.ical model has the ***,through extensive simulations,we characterize the HPVC MAC performance under different system parameters and verify the correctness of the corresponding analy.ical model with an average error rate of 4.62%between the simulation and analy.ical results.

关键词： Hybrid power-line/Visible light communication (HPVC)networks MAC protocol CSMA/CA IEEE 802.15.7 IEEE 1901 Performance analy.is

Kinetic-Thermodynamic Promotion Engineering toward High-Density Hierarchical and Zn-Doping Activity-Enhancing ZnNiO@CF for High-Capacity Desalination

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Nano-Micro Letters 2024年第8期16卷 35-50页

作者： Jie Ma Siyang Xing yabo Wang Jinhu yang fei yu College of Marine Ecology and Environment Shanghai Ocean University201306 ShanghaiPeople’s Republic of China School of Civil Engineering Kashi University844000 KashiPeople’s Republic of China Research Center for Environmental Functional Materials College of Environmental Science and EngineeringTongji University1239 Siping Road200092 ShanghaiPeople’s Republic of China School of Chemical Science and Engineering Tongji University1239 Siping Road200092 ShanghaiPeople’s Republic of China Department of Energy Environmental&Chemical EngineeringWashington University in St.LouisSt.LouisMO 63130USA

Despite the promising potential of transition metal oxides(TMOs)as capacitive deionization(CDI)electrodes,the actual capacity of TMOs electrodes for sodium storage is significantly.lower than the theoretical capacity,posing a major ***,we prepared the kinetically.favorable Zn_(x)Ni_(1−x)O electrode in situ growth on carbon felt(Zn_(x)Ni_(1−x)O@CF)through constraining the rate of OH^(−)generation in the hydrothermal ***_(x)Ni_(1−x)O@CF exhibited a high-density hierarchical nanosheet structure with three-dimensional open pores,benefitting the ion transport/electron *** tuning the moderate amount of redox-inert Zn-doping can enhance surface electroactive sites,actual activity of redox-active Ni species,and lower adsorption energy,promoting the adsorption kinetic and thermodynamic of the Zn_(0.2)Ni_(0.8)O@*** from the kinetic-thermodynamic facilitation mechanism,Zn_(0.2)Ni_(0.8)O@CF achieved ultrahigh desalination capacity(128.9 mgNaCl g^(-1)),ultra-low energy consumption(0.164 kW h kgNaCl^(-1)),high salt removal rate(1.21 mgNaCl g^(-1) min^(-1)),and good *** thermodynamic facilitation and Na^(+)intercalation mechanism of Zn_(0.2)Ni_(0.8)O@CF are identified by the density functional theory calculations and electrochemical quartz crystal microbalance with dissipation monitoring,*** research provides new insights into controlling electrochemically.favorable morphology and demonstrates that Zn-doping,which is redox-inert,is essential for enhancing the electrochemical performance of CDI electrodes.

关键词： Zinc-nickel metal oxide High-density hierarchical Capacitive deionization Zinc-doping

High Dynamic Bounding and Jumping Motion of Quadruped Robot Based on Stable Optimization Control

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Journal of Bionic Engineering 2024年第1期21卷 101-111页

作者： Sai Gu fei Meng Botao Liu Junyao Gao Qiang Huang School of Mechatronical Engineering Beijing Institute of Technology100081 BeijingChina Key Laboratory of Biomimetic Robots and Systems Ministry of EducationBeijing 100081China

Aiming at the environment such as ravines and obstacles that may be encountered in the actual movement,this paper proposes a method for optimizing the bounding and jumping motion based on the ground touching force trajectory and the air motion trajectory of the quadruped *** method of optimizing the ground reaction force according to the speed of the demand and the height of the jump,and adjusting the stance and swing time according to the relationship of dynamics and momentum *** the same time,under the constraints of dynamics and energy consumption of the robot system,considering the jumping distance and height,a method for optimizing the air trajectory of bounding and jumping is *** switching and landing stability control are also ***,the experimental results show that the quadruped robot has strong bounding and jumping ability,and has achieved stable bounding movement and forward jump movement of 0.8 m.

关键词： Quadruped robot High dynamic motion control-Periodic limit cycle Trajectory optimization

A DFT study on Pt single atom loaded COF for efficient photocataly.ic CO_(2)reduction

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Journal of Materials Science & Technology 2024年第3期170卷 87-94页

作者： fei Xie Chuanbiao Bie Jian Sun Zhenyi Zhang Bicheng Zhu Laboratory of Solar Fuel Faculty of Materials Science and ChemistryChina University of GeosciencesWuhan430078China Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission Key Laboratory of Photosensitive Materials and Devices of Liaoning ProvinceSchool of Physics and Materials EngineeringDalian Minzu UniversityDalian116600China

Photocataly.ic CO_(2)reduction provides a promising strategy for the alleviation of greenhouse effect and energy shortage *** single atom modification is an effective method to improve the CO_(2)reduction performance of covalent organic framework(COF)photocataly.ts,while the intrinsic mechanism is not revealed in ***,a Pt-COF photocataly.ic system was constructed by embedding Pt single atom in TFPT-TMT-COF(TFPT:1,3,5-tris(4-formylphenyl)-triazine,TMT:2,4,6-trimethyl-1,3,5-triazine).Based on density functional theory(DFT)calculation,the geometric structure and electronic property of Pt-COF were investigated,and the CO_(2)adsorption and reduction reaction process on Pt-COF were *** results show that the Pt atom can be steadily.anchored in COF via the formation of Pt-N and Pt-C ***,there is strong electronic interaction between Pt and *** incorporation of Pt atom benefits the CO_(2)reduction activity of COF from multiple aspects:(ⅰ)reducing the band gap and improving light absorption;(ⅱ)enhancing CO_(2)adsorption and activating the CO_(2)molecule;(ⅲ)decreasing the energy barrier in the hydrogenation step of CO_(2)→COOH,thus facilitating CO_(2)conversion to CO;(ⅳ)inhibiting the hydrogenation of CO,thereby increasing the selectivity of *** work brings a novel insight into the excellent CO_(2)reduction performance of Pt modified COF,and provides useful references for the design of single atom photocataly.ts.

关键词： Photocataly.is Carbon dioxide reduction Covalent organic framework Pt single atom Theoretical calculation