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Nano Research 2024年第6期17卷 5670-5679页

作者： Yong Wang Dingyi Yang Wei xu Yongjie xu Yu Zhang Zixuan Cheng Yizhang Wu xuetao Gan Wei Zhong Yan Liu Genquan Han Yue Hao Wide Bandgap Semiconductor technology Disciplines State Key Laboratory School of MicroelectronicsAcademy of Advanced Interdisciplinary ResearchXidian UniversityXi’an 710071China Emerging Device and Chip Laboratory Hangzhou Institute of TechnologyXidian UniversityHangzhou 311200China INRS Centre for Energy Materials and Telecommunications1650 Boul.Lionel BouletVarennesQC J3X 1P7Canada National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures and Jiangsu Provincial Key Laboratory for NanotechnologyNanjing UniversityNanjing 210093China School of Education Jiangsu Open UniversityNanjing 210036China department of Physics Shaanxi University of Science and TechnologyXi’an 710021China department of applied Physical Sciences The University of North Carolina at Chapel HillChapel HillNC 27514USA Key Laboratory of Light Field Manipulation and Information Acquisition Ministry of Industry and Information Technologyand Shaanxi Key Laboratory of Optical Information TechnologySchool of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi'an 710129 China

Two-dimensional(2D)materials that combine ferromagnetic,semiconductor,and piezoelectric properties hold significant potential for both fundamental research and spin electronic ***,the majority of reported 2D ferromagnetic-semiconductor-piezoelectric materials rely on d-electron systems,which limits their practical applications due to a Curie temperature lower than room temperature(RT).Here,we report a high-crystallinity carbon nitride(CCN)material based on sp-electrons using a chemical vapor deposition *** exhibits a band gap of 1.8 eV and has been confirmed to possess substantial in-plane and out-of-plane ***,we acquired clear evidences of ferromagnetic behavior at room *** structural characterizations combined with theoretical calculations reveal that incorporating structural oxygen into the highly ordered heptazine structure causes partial substitution of nitrogen sites,which is primarily responsible for generating room-temperature ferromagnetism and *** a result,the strain in wrinkles can effectively modulate the domain behavior and piezoelectric potential at room *** addition of RT ferromagnetic-semiconductor-piezoelectric material based on sp-electrons to the family of two-dimensional materials opens up numerous possibilities for novel applications in fundamental research and spin electronic devices.

关键词： crystallinity carbon nitride room-temperature ferromagnetism piezoelectricity magnetic force microscopy density functional theory(DFT)calculations

Quantifying trapping stability of optical tweezers with an external flow

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Photonics Research 2024年第8期12卷 1741-1749页

作者： FENG xu YARONG YU YANG LIU YAO CHANG WENXIANG JIAO LIN WANG HOPUI HO BEI WU FEI xu YANQING LU YUANJIE PANG GUANGHUI WANG College of Engineering and applied Sciences Nanjing UniversityNanjing 210093China Key Laboratory of Intelligent Optical Sensing and Integration of the Ministry of Education Nanjing UniversityNanjing 210093China School of Optical and Electronic Information Wuhan National Laboratory of OptoelectronicsHuazhong University of Science and TechnologyWuhan 430074China department of Biomedical Engineering The Chinese University of Hong KongHong Kong 999077China

Optical tweezers(OTs)can immobilize and manipulate objects with sizes that span between nano-and micrometer *** manipulating ability of OTs is traditionally characterized by stability factor(S),which can only indicate an empirical“hit-or-miss”***,the current quantitative models for trapping stability rarely consider the influence of external *** this paper,a comprehensive analysis to quantify the optical trapping stability in a perturbed asymmetric potential well is presented from the perspective of statistics,especially for weak trapping *** analytical formulation takes experimentally measurable parameters including particle size,optical power,and spot width as inputs and precisely outputs a statistically relevant mean trapping ***,this formulation takes into account general and realistic cases including fluidic flow velocity and other *** verify the model,a back-focal-plane-interferometer-monitored trapping experiment in a flow is set up and the statistical characteristics of trapping time demonstrate good agreement with theoretical *** total,the model quantitatively reveals the effects of external disturbance on trapping time,which will find applications where optical trapping stability is challenged by external perturbations in weak trapping conditions.

关键词： process flow trapping

PULSATILE BLOOD FLOW THROUGH A VISCOELASTICITY-TETHERED TUBE OF MILD VARYING CROSS-SECTION

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Journal of Hydrodynamics 1989年第2期1卷 32-44页

作者： xu Shi-xiong Zhang Xiao-dong Liu Zao-rong department of applied Mechanics,Fudan university,Shanghai,P.R.china

In this paper a mathematical model is developed for the description of the pulsatile blood flow through an axisymmetric artery of mild varying cross-section, taking into account the tethering effect of the sorrounding *** on the linear Navier-Stokes equation and boundary conditions,a set of differential equa- tions for the modulus of phase velocity,blood velocities,pressure and deformation of the vessel wall are deduced and the numerical solutions are found by utilizing the Runge-Kutta *** axial velocity profiles and the peak wall shear stresses are given for both mild tapering tube and mild stenosed *** is shown that the peak wall shear stresses in the tethered tube are higher than those in the free *** is also shown that in a series of previously research work on peak wall shear stresses of varying cross-section vessels the free vessel assumption has the tendency of under assessing the peak wall shear stresses and vice versa for the rigid vessel assumption.

关键词： Flow PULSATILE BLOOD FLOW THROUGH A VISCOELASTICITY-TETHERED TUBE OF MILD VARYING CROSS-SECTION MILD

An Uncertain Bang-Bang Control Model

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An Uncertain Bang-Bang Control Model

Mastering air combat game with deep reinforcement learning

第九届中国不确定系统年会、第五届中国智能计算大会、第十三届中国青年信息与管理学者大会

作者： Xinxin xu,Yuanguo Zhu department of applied mathematics,Nanjing university of Science and technology Nanjing 210094,Jiangsu,People's Republic of china

In this paper,we present an uncertain Bang-Bang control by using the equation of optimality in uncertain optimal *** example is given to illustrate the result obtained.

关键词： uncertain optimal control uncertain process equation of optimality Bang-Bang control

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Defence technology（防务技术） 2024年第4期34卷 295-312页

作者： Jingyu Zhu Minchi Kuang Wenqing Zhou Heng Shi Jihong Zhu xu Han department of Precision Instruments Tsinghua UniversityBeijing 100084China department of Computer Science and technology Tsinghua UniversityBeijing 100084China Chengdu Aircraft Design&Research Institute Aviation Industry Corporation of ChinaChengdu 610000China

Reinforcement learning has been applied to air combat problems in recent years,and the idea of curriculum learning is often used for reinforcement learning,but traditional curriculum learning suffers from the problem of plasticity loss in neural *** loss is the difficulty of learning new knowledge after the network has *** this end,we propose a motivational curriculum learning distributed proximal policy optimization(MCLDPPO)algorithm,through which trained agents can significantly outperform the predictive game tree and mainstream reinforcement learning *** motivational curriculum learning is designed to help the agent gradually improve its combat ability by observing the agent's unsatisfactory performance and providing appropriate rewards as a ***,a complete tactical maneuver is encapsulated based on the existing air combat knowledge,and through the flexible use of these maneuvers,some tactics beyond human knowledge can be *** addition,we designed an interruption mechanism for the agent to increase the frequency of decisionmaking when the agent faces an *** the number of threats received by the agent changes,the current action is interrupted in order to reacquire observations and make decisions *** the interruption mechanism can significantly improve the performance of the *** simulate actual air combat better,we use digital twin technology to simulate real air battles and propose a parallel battlefield mechanism that can run multiple simulation environments simultaneously,effectively improving data *** experimental results demonstrate that the agent can fully utilize the situational information to make reasonable decisions and provide tactical adaptation in the air combat,verifying the effectiveness of the algorithmic framework proposed in this paper.

关键词： Air combat MCLDPPO Interruption mechanism Digital twin Distributed system

Significant annealing-induced hardening effect in nanolaminate d-nanotwinne d(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)me dium-entropy alloy by severe cold rolling

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Journal of Materials Science & technology 2024年第3期170卷 156-166页

作者： Shuqing Yuan Hui Fu Lei Qian Chi Fai Cheung xu-Sheng Yang State Key Laboratory of Ultra-precision Machining technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Hong Kong Polytechnic university Shenzhen Research Institute Shenzhen 518060China

Due to the easy coarsening caused by poor thermal stability,the verified annealing-induced hardening in nanograined metals can only maintain at a relatively low-temperature *** this study,a nanolam-inated(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)medium-entropy alloy with an average lamellae thickness of∼20 nm embedded by thinner nanotwins was fabricated by severe cold rolling to achieve superior thermal *** with the conventional nanotwinned CrCoNi with nanotwins inside ultra-fined grains,the hier-archical nanolaminated-nanotwinned(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8) exhibits a significant annealing-induced hard-ening effect,i.e.,hardness increasing from∼250 HV in the original specimen to∼500 HV in the cold-rolled status and finally∼630 HV after annealing at 600℃for 1 *** microstructure characterizations reveal that the reduced dislocation density and formation of L1_(2)ordered domain are mainly responsible for such hardening effect,which is facilitated by the effectively suppressed coarsening with annealing temperature,i.e.,slow detwinning process and well-retained low-angle nanolamellar *** coarsening mechanisms from the cold-rolled nanolamellae to the fully recrystallized micro-equiaxed structures under the annealing temperatures ranging from 400 to 800℃ were also elucidated by atomic observations.

关键词： Annealing-induced hardening Thermal stability Nanolaminated-nanotwinned structure CrCoNi Detwinning Grain boundary migration

Crop Yield and Soil Responses to Long-Term Fertilization on a Red Soil in Southern china

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Pedosphere 2009年第2期19卷 199-207页

作者： ZHANG Hui-Min WANG Bo-Ren xu Ming-Gang FAN Ting-Lu Key Laboratory of Plant Nutrition and Nutrient Cycling Ministry of Agriculture of China and Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 China department of Resource and Environment Northwest Sci-Tech University of Agriculture and Forestry Yangling 712100 China department of Agronomy Henan University of Science and Technology Luoyang 471003 China

A 15-year fertilization experiment with different applications of inorganic N,P and K fertilizers and farmyard manure (M)was conducted to study the yield and soil responses to long-term fertilization at Qiyang,Hunan Province,china. Average grain yields of wheat and corn(1 672 and 5 111 kg ha-1,respectively)for the treatment NPKM were significantly higher than those(405 and 310 kg ha-1)of the unfertilized control and single inorganic fertilizer *** with the corresponding initial values of the experiment,all treatments showed a yield decline of 9 to 111 kg ha-1 year-1 in wheat and 35 to 260 kg ha-1 year-1 in corn,respectively,and a significant pH decline of 0.07 to 0.12 pH year?1,except for the treatments PK and *** long-term fertilization,the soil organic C,soil available P,exchangeable Ca2+ and Mg2+and available Cu2+and Zn2+contents were higher in the treatment NPKM than in the treatments applied with inorganic fertilizer *** to the treatment NPK,the treatment NPKM,where manure partially replaced inorganic N,had a positive impact on arresting the decline of soil *** improved grain yields of wheat and corn, suggesting that application of NPK fertilizer in combination with farmyard manure is important to maintain soil fertility and buffering capacity in red soil.

关键词： corn long-term fertilization red soil wheat yield

Hybrid tri-memristor hyperchaotic map and application in Wasserstein Generative Adversarial Nets

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Science china(Technological Sciences) 2024年第6期67卷 1855-1865页

作者： GU Yang BAO Han YU XiHong HUA ZhongYun BAO BoCheng xu Quan School of Microelectronics and Control Engineering Changzhou UniversityChangzhou213159China School of Computer Science and technology Harbin Institute of TechnologyShenzhen518055China

Inspired by basic circuit connection methods,memristors can also be utilized in the construction of complex discrete chaotic *** investigate the dynamical effects of hybrid memristors,we propose two hybrid tri-memristor hyperchaotic(HTMH)mapping structures based on the hybrid parallel/cascade and cascade/parallel operations,*** the HTMH mapping structure with hybrid parallel/cascade operation as an example,this map possesses a spatial invariant set whose stability is closely related to the initial states of the *** distributions and bifurcation behaviours dependent on the control parameters are explored with numerical ***,the memristor initial offset-boosting mechanism is theoretically demonstrated,and memristor initial offset-boosting behaviours are numerically *** results clarify that the HTMH map can exhibit hyperchaotic behaviours and extreme multistability with homogeneous coexisting infinite *** addition,an FPGA hardware platform is fabricated to implement the HTMH map and generate pseudorandom numbers(PRNs)with high ***,the generated PRNs can be applied in Wasserstein generative adversarial nets(WGANs)to enhance training stability and generation capability.

关键词： memristor hybrid tri-memristor map spatial invariant set hyperchaos extreme multistability generative adversarial nets

Multi-Fidelity Simulation of Gas Turbine Overall Performance by Directly Coupling High-Fidelity Models of Multiple Rotating Components

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Journal of Thermal Science 2024年第4期33卷 1357-1378页

作者： DENG Weimin xu Yibing NI Ming WEI Zuojun GAN Xiaohua REN Guangming department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen518055China School of Aerospace Engineering Tsinghua UniversityBeijing100084China Shenzhen Key Laboratory of Wide-Speed-Range and Variable-Density Continuous Wind Tunnel Shenzhen Science and Technology Innovation CommitteeShenzhen518000China

Multi-fidelity simulations incorporate computational fluid dynamics(CFD) models into a thermodynamic model,enabling the simulation of the overall performance of an entire gas turbine with high-fidelity *** iterative coupled methods rely on characteristic maps,while fully coupled methods directly incorporate high-fidelity ***,fully coupled methods face challenges in simulating rotating components,including weak convergence and complex *** address these challenges,a fully coupled method with logarithmic transformations was developed to directly integrate high-fidelity CFD models of multiple rotating *** developed fully coupled method was then applied to evaluate the overall performance of a KJ66 micro gas turbine across various off-design *** developed fully coupled method was also compared with the traditional iterative coupled ***,experimental data from ground tests were conducted to verify its *** convergence history indicated that the proposed fully coupled method exhibited stable convergence,even under far-off-design *** experimental verification demonstrated that the multi-fidelity simulation with the fully coupled method achieved high accuracy in off-design *** analysis revealed inherent differences in the coupling methods of CFD models between the developed fully coupled and traditional iterative coupled *** inherent differences provide valuable insights for reducing errors between the component-level model and CFD models in different coupling *** developed fully coupled method,introducing logarithmic transformations,offers more realistic support for the detailed and optimal design of high-fidelity rotating components within the overall performance platform of gas turbines.

关键词： multi-fidelity fully coupled method iterative coupled method gas turbine component-level model