检索结果-南通市图书馆

Electro-optic 3D snapshot of a laser wakefield accelerated kilo-ampere electron bunch

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第5期13卷 823-834页

作者： Kai Huang zhan Jin Nobuhiko Nakanii Tomonao Hosokai Masaki Kando Kansai Institute for Photon Science(KPSI) National Institutes for Quantum Science and Technology(QST)KyotoJapan. Laser Accelerator R&D Innovative Light Sources DivisionRIKEN SPring-8 CenterHyogoJapan. SANKEN Osaka UniversityOsakaJapan

Laser wakefield acceleration,as an advanced accelerator concept,has attracted great attentions for its ultrahigh acceleration gradient and the capability to produce high brightness electron *** three-dimensional(3D)density serves as an evaluation metric for the particle bunch quality and is intrinsically related to the applications of an *** its significance,this parameter has not been experimentally measured in the investigation of laser wakefield *** report on an electro-optic 3D snapshot of a laser wakefield electron bunch at a position outside the *** 3D shape of the electron bunch was detected by simultaneously performing optical transition radiation imaging and electro-optic *** 3D structures to a few micrometer levels were reconstructed using a genetic *** electron bunch possessed a transverse size of less than 30 *** current profile shows a multi-peak *** main peak had a duration of1 *** maximum electron 3D number density was~9×10^(21)m^(-3).This research demonstrates a feasible way of 3D density monitoring on femtosecond kilo-ampere electron bunches,at any position of a beam transport line for relevant applications.

关键词： laser acceleration field

Deadline-Constrained and Cost-Effective Multi-Workflow Scheduling with Uncertainty in Cloud Control Systems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第5期37卷 1861-1886页

作者： YE Lingjuan YANG Liwen XIA Yuanqing zhan Yufeng ZHAO Xinchao School of Science Beijing University of Posts and Telecommunications Key Laboratory of Mathematics and Information Networks Beijing University of Posts and Telecommunications Ministry of Education School of Automation Nanjing University of Information Science and Technology School of Automation Beijing Institute of Technology

In cloud control systems, generating an efficient and economical workflow scheduling strategy for deadline-constrained workflow applications, especially in uncertain multi-workflow dynamic scheduling processes, is a crucial challenge. To optimize the total cost of workflow scheduling, the authors propose a cost-driven heuristic scheduling algorithm F-MWSA which consists of two phases:Fuzzy deadline distribution and fuzzy task scheduling. In the fuzzy deadline distribution phase, a new workflow deadline distribution strategy with fuzziness is designed to obtain the sub-deadline constraint of each task. The fuzzy task scheduling phase focuses on a cost-effective strategy to assign tasks to cloud resources, reducing multi-workflow scheduling costs. Performance evaluations on five real-world workflows demonstrate that the proposed F-MWSA outperforms the baseline policy in terms of total cost, success ratio, resource utilization, and makespan.

关键词： Cloud computing cost-effective deadline constraint multi-workflow scheduling uncertainty

Aero-structural design of joined-wing aircraft based on high-fidelity model

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第4期37卷 363-377页

作者： Cheng HE Fengjiang zhan Luchuang MA Gang CHEN Jianying MA Unmanned Air Vehicle Research Institute Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Advanced Technology for Small and Medium-sized UAV Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China Aerospace System Engineering Shanghai Shanghai 201108China

The joined-wing configuration reduces induced drag and structural weight by connecting the rear wing to the front *** addition,the rear wing can replace the role of the horizontal tail of a conventional aircraft,thus eliminating the aerodynamic drag and weight associated with the horizontal *** particular shape creates a highly coupled relationship between aerodynamics and structure,which must be fully considered during the overall design process to enhance aircraft *** this research,an aero-structural design model of the joined-wing aircraft is constructed based on high-fidelity computational fluid dynamics and structural finite element *** model is able to obtain accurate aerodynamic loads for the non-planar wing and to simulate the statically indeterminate structure of the closed wing *** influence of the joined-wing shape parameters on the aerodynamic and structural disciplines,as well as the influence of geometric nonlinear characteristics,deformation constraints and buckling constraints on the structural weight are all taken into *** model is applied to complete the aero-structural design optimization of a high-altitude long-endurance joined-wing aircraft,and wind tunnel tests are *** test results verify the credibility of the design model proposed and the validity of the design environment.

关键词： Joined-wing configuration Aircraft design Aero-structural design Finite element Wind tunnel test

Iron-nickel alloy particles with N-doped carbon “armor” as a highly selective and long-lasting catalyst for the synthesis of Nbenzylaniline molecules

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第4期17卷 2308-2319页

作者： Gang Wang Longchao Sun Wanyi Liu Haijuan zhan Shuxian Bi College of Chemistry and Chemical Engineering Ningxia UniversityYinchuan 750021China

A scalable strategy for the convenient and rapid preparation of nitrogen-doped carbon-coated iron-based alloy catalysts was *** controlling the type and amount of metal salts in the precursor,various types of nitrogen-doped carbon-coated alloy catalysts can be prepared in a targeted ***_(2)Ni2@CN materials with small particle sizes and relatively homogeneous basic sites showed promising results in the N-alkylation reaction of benzyl alcohol with aniline(optimum yield:99%).It is worth noting that the catalyst can also be magnetically separated and recovered after the reaction,and its performance can be regenerated through simple ***,it was confirmed by kinetic experiments that the activation of C–H at the benzyl alcohol benzylic position is the rate-determining step(RDS).According to density flooding theory calculations,Fe_(2)Ni2@CN catalysts require less energy than other materials(Fe@CN and Ni@CN)for the RDS(dehydrogenation reaction)*** N-alkylation reactions are more easily carried out on Fe_(2)Ni2@CN catalysts,which may be the reason for the best catalytic activity of Fe-Ni alloy *** carbon-coated alloy materials will show great potential in more types of heterogeneous catalysis.

关键词： iron-nickel alloy catalyst N-alkylation reaction magnetic separation reaction path dehydrogenation reaction

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Stabilizing iridium sites via interface and reconstruction regulations for water oxidation in alkaline and acidic media

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第2期89卷 355-363,I0009页

作者： Weibin Chen Yanhui Song Lei Li Junjie Guo zhan Lin Guangdong Provincial Key Laboratory of Plant Resources Biorefinery School of Chemical Engineering and Light IndustryGuangdong University of TechnologyGuangzhou 510006GuangdongChina Key Laboratory of Interface Science and Engineering in AdvancedMaterials Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024ShanxiChina

Exploring effective iridium(Ir)-based electrocatalysts with stable iridium centers is highly desirable for oxygen evolution reaction(OER).Herein,we regulated the incorporation manner of Ir in Co_(3)O_(4)support to stabilize the Ir sites for effective *** anchored on the surface of Co_(3)O_(4)in the form of Ir(OH)_6 species,the created Ir-OH-Co interface leads to a limited stability and poor acidic OER due to Ir *** doped into Co_(3)O_(4)lattice,the analyses of X-ray absorption spectroscopy,in-situ Raman,and OER measurements show that the partially replacement of Co in Co_(3)O_(4)by Ir atoms inclines to cause strong electronic effect and activate lattice oxygen in the presence of Ir-O-Co interface,and simultaneously master the reconstruction effect to mitigate Ir dissolution,realizing the improved OER activity and stability in alkaline and acidic *** a result,Ir_(lat)@Co_(3)O_(4)with Ir loading of 3.67 wt%requires 294±4 mV/285±3 mV and 326±2 mV to deliver 10 mA cm^(-2)in alkaline(0.1 M KOH/1.0 M KOH)and acidic(0.5 M H_(2)SO_(4))solution,respectively,with good stability.

关键词： Interface effect Reconstruction Ir dissolution Ir-O-Co Oxygen evolution reaction

On the Well-Posedness Problem of the Anisotropic Porous Medium Equation with a Variable Diffusion Coefficient

在线全文

学校读者我要写书评

暂无评论

Journal of Partial Differential Equations 2024年第2期37卷 135-149页

作者： zhan Huashui School of Mathematics and Statistics Xiamen University of TechnologyXiamen 361024China

The initial-boundary value problem of an anisotropic porous medium equation■is *** with the usual porous medium equation,there are two different characteristics in this *** lies in its anisotropic property,another one is that there is a nonnegative variable diffusion coefficient a(x,t)*** a(x,t)may be degenerate on the parabolic boundary∂Ω×(0,T),instead of the boundedness of the gradient|∇u|for the usual porous medium,we can only show that∇u∈L^(∞)(0,T;L^(2)_(loc)(Ω)).Based on this property,the partial boundary value conditions matching up with the anisotropic porous medium equation are discovered and two stability theorems of weak solutions can be proved naturally.

关键词： Anisotropic porous medium equation variable diffusion coefficient stability partial boundary condition

Coherence entropy during propagation through complex media

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advanced Photonics 2024年第4期6卷 25-35页

作者： Xingyuan Lu Zhuoyi Wang Qiwen zhan Yangjian Cai Chengliang Zhao Soochow University School of Physical Science and TechnologyJiangsu Key Laboratory of Frontier Material Physics and DevicesSuzhouChina University of Shanghai for Science and Technology School of Optical-Electrical and Computer EngineeringShanghaiChina Shandong Normal University School of Physics and ElectronicsShandong Provincial Engineering and Technical Center of Light ManipulationsShandong Provincial Key Laboratory of Optics and Photonic DeviceJinanChina East China Normal University Joint Research Center of Light Manipulation Science and Photonic Integrated Chip of East China Normal University and Shandong Normal UniversityShanghaiChina

The deformation,flicker,and drift of a light field owing to complex media such as a turbulent atmosphere have limited its practical ***,research on invariants in randomly fluctuated light fields has garnered considerable attention in recent *** is a statistical property of light,while its full and quantitative characterization is ***,we successfully realize the orthogonal modal decomposition of partially coherent beams and introduce the application of coherence entropy as a global coherence characteristic of such randomly fluctuated light *** is demonstrated that coherence entropy remains consistent during propagation in a unitary system by unraveling complex *** representative examples,we study the robustness of coherence entropy for partially coherent beams as they propagate through deformed optical systems and turbulent *** entropy is anticipated to serve as a key metric for evaluating the propagation of partially coherent beams in complex *** study paves the way for a broader application scope of a customized low-coherence light field through nonideal optical systems and complex media.

关键词： complex media propagation invariant modal decomposition orbital angular momentum statistical optics coherence

Impact and prediction of pollutant on mangrove and carbon stocks:A machine learning study based on urban remote sensing data

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2024年第3期15卷 401-418页

作者： Mengjie Xu Chuanwang Sun Yanhong zhan Ye Liu Institute of Artificial Intelligence Xiamen UniversityXiamen 361005FujianChina China Center for Energy Economics Research School of EconomicsXiamen UniversityXiamen 361005FujianChina Laboratory of Smart Energy and Green Economy Institute of Artificial IntelligenceXiamen UniversityXiamen 361005FujianChina Department of Public Finance School of EconomicsXiamen UniversityXiamen 361005China

Mangrove ecosystems have important ecological and economic values,especially their ability to store ***,in recent years,human disturbance has accelerated mangrove *** them,the emission of pollutants cannot be *** is of great significance for carbon emission reduction and ecological protection to study the impacts of different pollutants on mangroves and their carbon *** on the remote sensing data of coastal areas south of the Yangtze River in China's Mainland,this paper builds the ensemble learning model Random Forest(RF)and Gradient Boosting Regression(GBR)to empirically analyse the relationship between industrial wastewater,industrial sulfur dioxide(SO2),PM2.5 and mangrove *** results show that the pollutant concentration of meteorological normalisation is more *** importance of pollutants presents regional *** area of mangroves in different cities and the corresponding total carbon stocks show different trends with the increase or decrease of pollutants,and there is a dynamic balance between urban pollutant discharge and mangrove growth in some *** research in this paper provides an analysis and explanation from the perspective of machine learning to explore the relationship between mangroves and pollutants and at the same time,provides scientific suggestions for the formulation of future pollutant emission policies in different cities.

关键词： Mangrove forests Pollutants Machine learning model Carbon stocks Regional heterogeneity