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Quick-scanning X-ray absorption fine structure beamline at SSRF

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Nuclear Science and Techniques 2024年第6期35卷 1-13页

作者： Yu Chen qian gao Zheng Jiang Jiong Li Shuo Zhang Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China

The layout and characteristics of the hard X-ray spectroscopy beamline(BL11B)at the Shanghai synchrotron radiation facility are described ***11B is a bending-magnet beamline dedicated to conventional and millisecond-scale quick-scanning X-ray absorption fine *** is equipped with a cylindrical collimating mirror,a double-crystal monochromator comprising Si(111)and Si(311),a channel-cut quick-scanning Si(111)monochromator,a toroidal focusing mirror,and a high harmonics rejection *** can provide 5-30 keV of X-rays with a photon flux of~5×10^(11)photons/s and an energy resolution of~1.31×10^(-4)at 10 *** performance of the beamline can satisfy the demands of users in the fields of catalysis,materials,and environmental *** paper presents an overview of the beamline design and a detailed description of its performance and capabilities.

关键词： Bending magnet beamline X-ray absorption fine structure Quick-scanning XAFS In situ Synchrotron radiation

Improved RF power performance via electrostatic shielding effect using AlGaN/GaN/graded-AlGaN/GaN double-channel structure

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Science China(Information Sciences) 2024年第4期67卷 341-342页

作者： Chunzhou SHI Ling YANG Meng ZHANG hao LU Mei WU Bin HOU Xuerui NIU qian YU Wenliang LIU Wenze gao Xiaohua MA Yue hao School of Advanced Materials and Nanotechnology Xidian University State Key Discipline Laboratory of Wide Bandgap Semiconductor Technology Xidian University

GaN-based high-electric-mobility transistors(HEMTs) have been investigated thoroughly because of their promising applications in high-frequency,-voltage, and-power applications. However, the theoretical material limit prevents conventional single-heterostructure GaN HEMTs from achieving high performance despite numerous efforts [1–3].

关键词： Drain current

Weakly Approximate Diagonalization of Homomorphisms into Finite von Neumann Algebras

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Acta Mathematica Sinica,English Series 2024年第9期40卷 2187-2194页

作者： Wen Hua qian Jun hao SHEN Wen Ming WU School of Mathematical Sciences Chongqing Normal UniversityChongqing 401331P.R.China Department of Mathematics and Statistics University of New HampshireDurhamNH 03824USA

Let A be a unital C^(∗)-algebra and B a unital C^(∗)-algebra with a faithful traceτ.Let n be a positive *** give the definition of weakly approximate diagonalization(with respect toτ)of a unital homomorphismφ:A→Mn(B).We give an equivalent characterization of McDuff Ⅱ_(1) *** show that,if A is a unital nuclear C^(∗)-algebra and B is a type Ⅱ_(1) factor with faithful traceτ,then every unital^(∗)-homomorphism φ:A→M_(n)(B)is weakly approximately *** B is a unital simple infinite dimensional separable nuclear C^(∗)-algebra,then any finitely many elements in Mn(B)can be simultaneously weakly approximately diagonalized while the elements in the diagonals can be required to be the same.

关键词： Weakly approximately diagonalizable McDuff factors nuclear hyperfinite

Isotopic insights on quantitative assessments of interaction of eco-hydrological processes in multi-scale karst watersheds

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International Soil and Water Conservation Research 2024年第1期12卷 156-170页

作者： Zhuo hao Yang gao Qingwen Zhang Wen Wen Agricultural Clean Watershed Research Group Institute of Environment and Sustainable Development in AgricultureCAASBeijing100081China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchCASBeijing100101China School of Humanities and Social Sciences Beijing Institute of TechnologyBeijing100081China

The dynamics of hydrological processes and the storage mechanisms of karst water resources are the most important issues in karst *** impact of environmental changes on water quantity,and the evaluation and quantification of eco-hydrological processes remain poorly *** this study,high-frequency continuous monitoring in multi-scale karst watersheds in Southwest China combined the approaches of water isotopes and the hybrid single-particle lagrangian integrated trajectory(HYSPLIT)model to identify the recharge mechanisms between atmospheric vapor,rainfall,surface water,and groundwater,and to reveal the interaction of eco-hydrological *** dominant moisture sources in Puding(PD)County were the Indian Ocean(43-69%)and local moisture(24-33%).Theδ^(18)O and deuterium excess(d-excess)values showed a positive correlation indicating that secondary or sub-cloud evaporation was prominent in the wet *** water line-conditioned excess(lc-excess)indicated that karst water interacted with recent precipitation,groundwater,and evaporation across *** to its specific hydrogeological structure,surface water and rainwater have a higher contribution rate to groundwater *** Chenqi stream replenished the Houzhai River mainly in the form of groundwater,with percentages ranging from 38.1 to 93.5%in the wet season,and 47.8-80.1%in the dry *** the Houzhai outlet,surface water and groundwater interconverted frequently with a percentage of 45.6-49.1%.We believe this is the first systematic study to quantify the supply relationship between water vapor transport,rainfall,surface water and groundwater in the Chinese karst zone,making a significant move forward in the field of karst hydrological processes and improving the efficiency of water resource evaluation and management.

关键词： Stable isotope Moisture sources Water cycle Karst watersheds

Flexible high-rise apartments with sparse wall-frame structure:A data-driven computational approach

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Frontiers of Architectural Research 2024年第3期13卷 639-649页

作者： hao Hua Ludger Hovestadt qian Wang School of Architecture Southeast UniversityNanjing 210096China Chair of Digital Architectonics ETH ZürichZürich 8093Switzerland Shanghai Huihuajia Software Technology Co. Ltd.Shanghai 200082China

Flexible housing resolves the fundamental conflicts between the long-standing structure and the evolving *** propose a computational method of optimizing the structural layout of high-rise residential *** high-rise apartment buildings have widely employed shear wall-frame structure in which one big room or multiple small rooms could occupy the same *** multiple floor plans into a fixed sparse scheme of shear walls and columns is *** developed a computational framework to seek flexible structural schemes.A building scheme consists of a circulation core,shear walls,columns,and *** computer program automatically adapts floor plans to any drawn or generated *** on a large dataset of apartment layouts,the number of apartments that fit into a building scheme statistically reflects the flexibility of the *** many hypothetical plans can fit into a wallframe structure in computer simulation,this structure could probably support several generations of unknown *** a data-driven computational method provides the possibility of creating a one-to-many mapping between permanent structure and evolving apartment plans.

关键词： Flexible housing High-rise apartment Data driven Computational design Wall-frame structure

Energy-absorbing porous materials:Bioinspired architecture and fabrication

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Nano Research 2024年第2期17卷 679-690页

作者： Junheng Zhao Meng Li Jiewei Chen Weiwei gao hao Bai State Key Laboratory of Chemical Engineering College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310058China Department of Polymer Science and Engineering Zhejiang UniversityHangzhou 310058China

Energy-absorbing materials are widely used in transportations,sports,and the military ***,porous materials,including natural and artificial materials,have attracted tremendous attentions due to their light weight and excellent energy absorption *** review summarizes the recent progresses in the natural and artificial energy-absorbing porous ***,we review the typical natural porous materials including cuttlebone,bighorn sheep horn,pomelo peel,and sunflower stem *** architectures,energy absorption abilities,and mechanisms of these typical natural materials and their bioinspired materials are ***,we provide a review on the fabrication methods of artificial energy-absorbing porous materials,such as conventional foaming and three-dimensional(3D)***,we address the challenges and prospects for the future development of energy-absorbing porous *** importantly,our review provides a direct guidance for the design and fabrication of energy-absorbing porous materials required for various engineering applications.

关键词： energy-absorbing porous materials natural materials natural structures bioinspired materials

Wind disturbance compensated path-following control for fixed-wing UAVs in arbitrarily strong winds

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Chinese Journal of Aeronautics 2024年第2期37卷 431-445页

作者： hao LU Lan gao Yunda YAN Mingzhe HOU Chenliang WANG Hangzhou Innovation Institute Beihang UniversityHangzhou 310051China School of Information Science and Technology Hangzhou Normal UniversityHangzhou 311121China Department of Computer Science University College LondonLondon WC1E 6BTUnited Kingdom Center for Control Theory and Guidance Technology Harbin Institute of TechnologyHarbin 150001China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

Wind is the primary challenge for low-speed fixed-wing unmanned aerial vehicles to follow a predefined flight *** cope with various wind conditions,this paper proposes a wind disturbance compensated path following control strategy where the wind disturbance estimate is incorporated with the nominal guiding vector field to provide the desired airspeed direction for the *** the control input vector for the outer-loop kinematic subsystem needs to satisfy a magnitude constraint,a scaling mechanism is introduced to tune the proportions of the compensation and nominal ***,an optimization problem is formulated to pursue a maximum wind compensation in strong winds,which can be solved analytically to yield two scaling factors.A cascaded inner-loop tracking controller is also designed to fulfill the outer-loop wind disturbance compensated guiding vector ***-fidelity simulation results under sensor noises and realistic winds demonstrate that the proposed path following algorithm is less sensitive to sensor noises,achieves promising accuracy in normal winds,and mitigates the deviation from a desired path in wild winds.

关键词： Path following Guiding vector field Wind disturbance Disturbance rejection Fixed wings

Atomistic understanding of rough surface on the interfacial friction behavior during the chemical mechanical polishing process of diamond

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Friction 2024年第6期12卷 1119-1132页

作者： Song YUAN Xiaoguang GUO hao WANG Renke KANG Shang gao State Key Laboratory of High-performance Precision Manufacturing Dalian University of TechnologyDalian 116024China

The roughness of the contact surface exerts a vital role in *** is still a significant challenge to understand the microscopic contact of the rough surface at the atomic ***,the rough surface with a special root mean square(RMS)value is constructed by multivariate Weierstrass–Mandelbrot(W–M)function and the rubbing process during that the chemical mechanical polishing(CMP)process of diamond is mimicked utilizing the reactive force field molecular dynamics(ReaxFF MD)*** is found that the contact area A/A0 is positively related with the load,and the friction force F depends on the number of interfacial bridge *** the surface roughness will increase the friction force and friction *** model with low roughness and high lubrication has less friction force,and the presence of polishing liquid molecules can decrease the friction force and friction *** RMS value and the degree of damage show a functional relationship with the applied load and lubrication,i.e.,the RMS value decreases more under larger load and higher lubrication,and the diamond substrate occurs severer damage under larger load and lower *** work will generate fresh insight into the understanding of the microscopic contact of the rough surface at the atomic level.

关键词： diamond random roughness reactive force field molecular dynamics(ReaxFF MD) friction Weierstrass-Mandelbrot(W-M)function chemical mechanical polishing(CMP)

Fairness in machine learning: definition, testing,debugging, and application

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Science China(Information Sciences) 2024年第9期67卷 41-61页

作者： Xuanqi gao Chao SHEN Weipeng JIANG Chenhao LIN qian LI qian WANG Qi LI Xiaohong GUAN Faculty of Electronic and Information Engineering Xi'an Jiaotong University School of Cyber Science and Engineering Wuhan University Institute for Network Sciences and Cyberspace Tsinghua University

In recent years, artificial intelligence technology has been widely used in many fields, such as computer vision, natural language processing and autonomous driving. Machine learning algorithms, as the core technique of AI, have significantly facilitated people's lives. However, underlying fairness issues in machine learning systems can pose risks to individual fairness and social security. Studying fairness definitions, sources of problems, and testing and debugging methods of fairness can help ensure the fairness of machine learning systems and promote the wide application of artificial intelligence technology in various fields. This paper introduces relevant definitions of machine learning fairness and analyzes the sources of fairness problems. Besides, it provides guidance on fairness testing and debugging methods and summarizes popular datasets. This paper also discusses the technical advancements in machine learning fairness and highlights future challenges in this area.

关键词： artificial intelligence security machine learning security machine learning fairness model testing model debugging