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Luminescence and magnetic properties of bifunctional nanoparticles composited by nitrogen-doped graphene quantum dots and gadolinium

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Journal of Rare Earths 2024年第4期42卷 716-723页

作者： Wanli Zhang hao Zhou Meigui Ou Donghao Sun Chunlin Yang College of Materials and Metallurgy University of GuizhouGuiyang550025China National Local Co-construction Engineering Laboratory for High Performance Metal Structure Material and Manufacture Technology Guiyang550025 China College of Chemistry and Materials Engineering Guiyang UniversityGuiyang550003China

In this paper,nitrogen-doped graphene quantum dots(N-GQDs)were combined with gadolinium ions(Gd^(3+))by a surface modification to obtain magneto-optical dual-functional N-GQDs/Gd^(3+)*** morphology of obtained composite was characterized by field emission scanning electron microscopy and transmission electron *** and magnetic properties were measured by a fluorescence spectrophotometer and a vibrating sample magnetometer,*** indicate that well-dispersed spherical N-GQDs/Gd^(3+)nanoparticles have an average diameter of 7 nm.N-doping significantly increases the luminesce nce of particles with an optimal luminescence intensity at 20℃and pH=9.X-ray photoelectron spectroscopy results indicate that the N-doping introduces pyrrolic N as an electron donor,enhancing fluorescence by increasing the surface electron cloud density of *** addition,density functional theory calculation results reveal that N-doping reduces the band gap of NGQDs/Gd^(3+),enabling electronic transitions to higher energy levels and generating more activation sites,thereby enhancing *** to N-GQDs/Gd^(3+)prepared at 20℃,the saturated magnetization of particles prepared at 40℃is 0.85 emu/g,indicating a better magnetic *** above results suggest that bifunctional nanomaterials N-GQDs/Gd^(3+)with excellent optical properties and magnetism can be better used for fluorescence and magnetic resonance imaging.

关键词： Nitrogen-doped graphenequantum dots Gadolinium Luminescence Magnetism Rare earths

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A comparative investigation on wear behaviors of physical and chemical vapor deposited bronze coatings for hydraulic piston pump

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Chinese Journal of Aeronautics 2024年第3期37卷 391-403页

作者： Wei hao Andrews LARBI Hongkang DONG Dongyun WANG Shenghu LI Zhejiang Provincial Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology and Equipment Zhejiang Normal UniversityJinhua 321004China College of Engineering Zhejiang Normal UniversityJinhua 321004China Hangzhou Lilong Hydraulic Co. LtdHangzhou 311200China

The cylinder block/valve plate interface is one of the most critical frictional interfaces of the swashplate-type axial piston ***,the poor lubrication interface caused rapid wear and high friction loss in an elastohydrodynamic lubrication system,decreasing the pump *** resistant bronze coatings were fabricated on 38CrMoAl substrate by Physical Vapor Deposition(PVD)and Chemical Vapor Deposition(CVD),***-on-disc wear tests were performed to comparatively investigate the wear behaviors of the coatings and bulk ductile iron *** can be found that the PVD-bronze coating exhibited better wear resistance than the other two *** enhanced wear resistance was attributed to the unique composite microstructure and desired mechanical strength,which could resist to mechanical shear and spallation,decreasing friction *** appropriate hardness of(1.33±0.07)GPa could be beneficial for enhancing its wear *** PVD-bronze coating possessed a much lower and stable coefficient of friction(about 0.1)and wear rate(about 6000μm3.N-1.m-1)under the loading forces of about 100 N after 20 *** wear mechanism was the abrasive wear.

关键词： Aircraft hydraulic pump Bronze Coatings Wear resistance Mechanisms

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Fractal Characteristics and Main Controlling Factors of High-Quality Tight Sandstone Reservoirs in the Southeastern Ordos Basin

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Journal of Earth Science 2024年第2期35卷 631-641页

作者： Ruilin hao Wenhui Huang Jiu Bo Li Yuan Key Laboratory for Marine Reservoir Evolution and Hydrocarbon Abundance Mechanism School of Energy ResourcesChina University of GeosciencesMinistry of EducationBeijing100083China

Due to the complex conditions and strong heterogeneity of tight sandstone reservoirs,the reservoirs should be classified and the controlling factors of physical properties should be *** thin section observations,cathodoluminescence,scanning electron microscopy(SEM),X-ray diffraction(XRD),and high-pressure mercury injection(HPMI)were used to classify and optimize the *** Brooks-Corey model and stepwise regression were used to study the fractal dimension and main controlling factors of the physical properties of the high-quality *** results show that the reservoirs in the study area can be divided into four types,and the high-quality reservoir has the best physical properties and pore-throat *** the high-quality reservoir,the homogeneity of transitional pores was the best,followed by that of micropores,and the worst was *** porosity was controlled by depth and *** model with standardized coefficients is y=12.454−0.778×(Depth)+0.395×(Kaolinite).The permeability was controlled by depth,illite/montmorillonite,and siliceous cement,and the model with standardized coefficients is y=1.689−0.683×(Depth)−0.395×(Illite/Montmorillonite)−0.337×(Siliceous Cement).The pore-throat evolutionary model shows that the early-middle diagenetic period was when the reservoir physical properties were at their best,and the kaolinite intercrystalline pores and residual intergranular pores were the most important.

关键词： fractal dimension main controlling factors stepwise regression high-quality tight sandstone reservoir Ordos Basin petroleum geolgoy

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Parametric formation control of multiple nanosatellites for cooperative observation of China Space Station

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Astrodynamics 2024年第1期8卷 77-95页

作者： hao Zhou Bohan Jiao Zhaohui Dang Jianping Yuan School of Astronautics Northwestern Polytechnical UniversityXi’an710072China National Key Laboratory of Aerospace Flight Dynamics Northwestern Polytechnical UniversityXi’an710072China

This study proposes a parametric formation control method for the cooperative observation of the China Space Station(CSS)using multiple ***,a simplified geometrical model of the CSS is constructed using fundamental solids,such as the capsule body and ***,the spacecraft formation configuration for the observation mission is characterized by a three-dimensional(3D)Lissajous curve using related design parameters under the full-coverage observation requirements of specific parts,such as the CSS connecting section and collision avoidance ***,a double-layer control law is designed for each nanosatellite,in which the upper layer is a distributed observer for recognizing the target formation configuration parameters,and the lower layer is a trajectory-tracking controller to make the nanosatellite converge to its temporary target position calculated from the upper layer’s *** closed-loop control stability is proven under the condition that the communication network topology of the nanosatellite cluster contains a directed spanning ***,the control method is verified by numerical simulation,where the CSS connecting section is selected as the observation target,and ten small nanosatellites are assumed to perform the cooperative observation *** simulation results demonstrate that the double-layer control law is robust to single-point communication failures and suitable for the accompanying missions of large space objects with multiple nanosatellites.

关键词： China Space Station(CSS) cooperative observation parametric formation 3D Lissajous curve double-layer system

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Primordial black holes and curvature perturbations from false vacuum islands

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Science China(Physics,Mechanics & Astronomy) 2024年第9期67卷 58-72页

作者： Rong-Gen Cai Yu-Shi hao shao-Jiang Wang School of Physical Science and Technology Ningbo UniversityNingbo 315211China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Asia Pacific Center for Theoretical Physics Pohang 37673Republic of Korea

Recently,much attention has been focused on the false vacuum islands that are flooded by an expanding ocean of true-vacuum bubbles slightly later than most of the other parts of the *** delayed decay regions will accumulate locally larger vacuum energy density by staying in the false vacuum longer than those already transited into the true vacuum.A false vacuum island with thus acquired density contrast of a super-horizon size will evolve locally from radiation dominance to vacuum dominance,creating a local baby Universe that can be regarded effectively as a local closed *** such density contrasts of super-horizon sizes can ever grow large enough to exceed the threshold of gravitational collapse,primordial black holes will form similar to those collapsing curvature perturbations on super-horizon scales induced by small-scale enhancements during *** not,such density contrasts can still induce curvature perturbations potentially observable *** this paper,we revisit and elaborate on the generations of primordial black holes and curvature perturbations from delayed-decayed false vacuum islands during asynchronous first-order phase transitions with fitting formulas convenient for future model-independent studies.

关键词： first-order phase transitions primordial black holes curvature perturbations

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基于跨学科学位的课程开放与融通机制探索——以英国开放大学开放学位为个案的分析

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成人教育 2024年第2期44卷 37-44页

作者：吴莎莎郝卫峰北京开放大学北京100081 北京联合大学北京100101

职业岗位需求的多样化催生了跨学科学位的人才培养模式。英国开放大学开放学位中“开箱”模式的设置为课程的融通建立了衔接的桥梁,学生根据自身需求选择学习的模块内容,将先前经验有效地融入到正式学科学习中。课程模块设置的特色主要... 详细信息

职业岗位需求的多样化催生了跨学科学位的人才培养模式。英国开放大学开放学位中“开箱”模式的设置为课程的融通建立了衔接的桥梁,学生根据自身需求选择学习的模块内容,将先前经验有效地融入到正式学科学习中。课程模块设置的特色主要是以职业发展为导向培养学生跨学科学习能力,建立了基于终身学习体系的可评估认证模式、基于远程教育平台的数字化运行方式、基于学习支持服务体系的可协调机制。开放教育学位改革是对教育评价改革方案的有效实践,而目前我国开放教育学位授予政策的灵活开放度方面还有待加强完善,在优化过程中可借鉴英开开放学位的跨学科性以及课程间开放与融通机制,真正体现开放大学“开放”与“融合”的办学特色。

关键词：跨学科开放学位课程开放融通机制认证模式

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Reduced-complexity multiple parameters estimation via toeplitz matrix triple iteration reconstruction with bistatic MIMO radar

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Chinese Journal of Aeronautics 2024年第7期37卷 482-495页

作者： Chenghong ZHAN Guoping HU Junpeng SHI Fangzheng Zhao hao ZHOU Graduate College Air Force Engineering UniversityXi’an 710051China Air and Missile Defense College Air Force Engineering UniversityXi’an 710051China College of Electronic Countermeasure National University of Defense TechnologyHefei 230037China Beijing Aeronautical Technology Research Center Beijing 100076China

In this advanced exploration, we focus on multiple parameters estimation in bistatic Multiple-Input Multiple-Output(MIMO) radar systems, a crucial technique for target localization and imaging. Our research innovatively addresses the joint estimation of the Direction of Departure(DOD), Direction of Arrival(DOA), and Doppler frequency for incoherent targets. We propose a novel approach that significantly reduces computational complexity by utilizing the TemporalSpatial Nested Sampling Model(TSNSM). Our methodology begins with a multi-linear mapping mechanism to efficiently eliminate unnecessary virtual Degrees of Freedom(DOFs) and reorganize the remaining ones. We then employ the Toeplitz matrix triple iteration reconstruction method, surpassing the traditional Temporal-Spatial Smoothing Window(TSSW) approach, to mitigate the single snapshot effect and reduce computational demands. We further refine the highdimensional ESPRIT algorithm for joint estimation of DOD, DOA, and Doppler frequency, eliminating the need for additional parameter pairing. Moreover, we meticulously derive the Cramér-Rao Bound(CRB) for the TSNSM. This signal model allows for a second expansion of DOFs in time and space domains, achieving high precision in target angle and Doppler frequency estimation with low computational complexity. Our adaptable algorithm is validated through simulations and is suitable for sparse array MIMO radars with various structures, ensuring higher precision in parameter estimation with less complexity burden.

关键词： MIMO Radar Multipleparameters estimation Temporal-spatial Nested Sampling Multi-linear mapping mechanism Toeplitz matrix triple iteration reconstruction Reduce computational complexity

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Performance Improvement of Two-Phase Steam Ejector based on CFD Techniques,Response Surface Methodology and Genetic Algorithm

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Journal of Thermal Science 2024年第2期33卷 675-695页

作者： ZHANG hao Zhao Hongxia ZHANG Xiuao ZENG Hongxuan DENG Jianqiang School of Energy and Power Engineering Shandong UniversityJi’nan250061China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an710049China

The steam ejector is a crucial component in the waste heat recovery *** performance determines the amount of recovered heat and system ***,poor ejector performance has always been the main bottleneck for system ***,this study proposes an optimization methodology to improve the steam ejector's performance by utilizing computational fluid dynamics(CFD) techniques,response surface methodology(RSM),and genetic algorithm(GA).Firstly,a homogeneous equilibrium model(HEM) was established to simulate the two-phase flow in the steam ***,the orthogonal test was presented to the screening of the key decision variables that have a significant impact on the entrainment ratio(ER).Next,the RSM was used to fit a response surface regression model(RSRM).Meanwhile,the effect of the interaction of geometric parameters on the performance of the steam ejector was ***,GA was employed to solve the RSRM's global optimal ER *** results show that the RSRM exhibits a good fit for ER(R^(2)=0.997).After RSM and GA optimization,the maximum ejector efficiency is 27.94%,which is 48.38% higher than the initial ejector of 18.83%.Furthermore,the optimized ejector efficiency is increased by 46.4% on average under off-design ***,the results reveal that the combination of CFD,RSM,and GA presents excellent reliability and feasibility in the optimization design of a two-phase steam ejector.

关键词： two-phase steam ejector optimization methodology CFD techniques response surface methodology genetic algorithm homogeneous equilibrium model

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Lead-free perovskites-based photonic synaptic devices with zero electric energy consumption

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Science China(Information Sciences) 2024年第6期67卷 433-441页

作者： Dandan hao Di YANG Haixia LIANG Jia HUANG Fukai shaN College of Electronics and Information Qingdao University Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of Sciences School of Materials Science and Engineering Tongji University National Key Laboratory of Autonomous Intelligent Unmanned Systems Tongji University

The von Neumann bottleneck is a critical limitation in synaptic devices. Therefore, artificial synaptic devices resembling biological neuromorphic synapses have been developed to overcome the von Neumann bottleneck. However, synaptic devices require voltages, which results in considerable energy consumption. Here, photonic synaptic devices with the vertical structure of indium tin oxide（ITO）/SnO2/Al2O3/CsBi3I10/Au are fabricated, which can work in the self-powered mode owing to the photovoltaic effect endowed by a vertical multilayer structure. Several fundamental synaptic functions, such as excitatory postsynaptic current, paired-pulse facilitation, short-term plasticity（STP）, long-term plasticity（LTP）, pulse-frequency-dependent plasticity, transition of STP to LTP, and the learning experience are emulated. Moreover, Morse-coded external light information is decoded by self-powered photonic synaptic devices. The results indicate that self-powered photonic synaptic devices based on lead-free perovskites exhibit great potential for efficient neuromorphic computing and optical wireless communication.

关键词： photonic synaptic devices lead-free perovskites zero energy consumption synaptic plasticity Morse code

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Full-domain collaborative deployment method of multiple interference sources and evaluation of its deployment effect

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Defence Technology（防务技术） 2024年第2期32卷 572-595页

作者： Yue Wang Fuping Sun Xian Wang Jinming hao Kai Xiao School of Geospatial Information The PLA Information Engineering UniversityZhengzhou 450001HenanChina

This paper realizes the full-domain collaborative deployment of multiple interference sources of the global satellite navigation system(GNSS)and evaluates the deployment effect to enhance the ability to disturb the attacker and the capability to defend the GNSS during navigation *** evaluation indicators for the jamming effect of GNSS suppressive and deceptive jamming sources are first created,their evaluation models are built,and their detection procedures are sorted out,as the basis for determining the deployment *** principles for collaboratively deploying multi-jamming sources are developed to obtain the deployment structures(including the required number,structures in demand,and corresponding positions)of three single interference sources required by collaboratively ***,simulation and hardware-in-loop testing results are presented to determine a rational configuration of the collaborative deployment of multi-jamming sources in the set situation and further realize the full-domain deployment of an interference network from ground,air to *** evaluation indices for the deployment effect are finally developed to evaluate the deployment effect of the proposed configuration and further verify its reliability and rationality.

关键词： Jamming effect Multiple interference sources Collaborative deployment Effect evaluation Defense capability

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