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Ramsey Number of K_(2,s+1) vs.K_(1,n)

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Chinese Quarterly Journal of Mathematics 2007年第1期22卷 12-15页

作者： QIN da-wei shen da-peng Department of Mathematics Tongji University Shanghai 200092 China

It is shown that the Ramsey number r（K2,s＋1,K1,n）≤n＋√sn＋（s＋3）/2＋o（1）for large n, and r（K2,s＋1, K1,n） ∈{（q-1）^2/s ＋ 1,（q-1）^2/s＋2},where n =（q-1）^2/s -q＋2 and q is a prime power such that s｜... 详细信息

关键词： Ramsey number Turán number double counting prime number theorem

Task-specific Part Discovery for Fine-grained Few-shot Classification

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Machine Intelligence Research 2024年第5期21卷 954-965页

作者： Yongxian wei Xiu-shen wei School of Computer Science and Technology Nanjing University of Science and TechnologyNanjing210094China

Localizing discriminative object parts(e.g.,bird head)is crucial for fine-grained classification tasks,especially for the more challenging fine-grained few-shot *** work always relies on the learned object parts in a unified manner,where they attend the same object parts(even with common attention weights)for different few-shot episodic *** this paper,we propose that it should adaptively capture the task-specific object parts that require attention for each few-shot task,since the parts that can distinguish different tasks are naturally *** for a few-shot task,after obtaining part-level deep features,we learn a task-specific part-based dictionary for both aligning and reweighting part features in an ***,part-level categorical prototypes are generated based on the part features of support data,which are later employed by calculating distances to classify query data for *** retain the discriminative ability of the part-level representations(i.e.,part features and part prototypes),we design an optimal transport solution that also utilizes query data in a transductive way to optimize the aforementioned distance calculation for the final *** experiments on five fine-grained benchmarks show the superiority of our method,especially for the 1-shot setting,gaining 0.12%,8.56%and 5.87%improvements over state-of-the-art methods on CUB,Stanford Dogs,and Stanford Cars,respectively.

关键词： Fine-grained image recognition few-shot learning transductive learning visual dictionary part feature discovery

High-resolution ARPES endstation for in situ electronic structure investigations at SSRF

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Nuclear Science and Techniques 2021年第3期32卷 94-106页

作者： Yi-Chen Yang Zheng-Tai Liu Ji-Shan Liu Zhong-Hao Liu Wan-Ling Liu Xiang-Le Lu Hong-Ping Mei Ang Li Mao Ye Shan Qiao da-wei shen State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049China

Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter *** ARPES,which uses photons with high flux and continuously tunable energy,has become particularly ***,an excellent synchrotron ARPES system must have features such as a small beam spot,super-high energy resolution,and a user-friendly operation interface.A synchrotron beamline and an endstation(BL03 U)were designed and constructed at the Shanghai Synchrotron Radiation *** beam spot size at the sample position is 7.5(V)μm×67(H)μm,and the fundamental photon range is 7-165 eV;the ARPES system enables photoemission with an energy resolution of 2.67 meV at21.2 *** addition,the ARPES system of this endstation is equipped with a six-axis cryogenic sample manipulator(the lowest temperature is 7 K)and is integrated with an oxide molecular beam epitaxy system and a scanning tunneling microscope,which can provide an advanced platform for in situ characterization of the fine electronic structure of condensed matter.

关键词： Synchrotron ARPES In situ VUV laser Quantum materials

Investigation of the room-temperature photoelectron spectroscopy of type-Ⅱ Weyl semimetal candidate WTe_(2)

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钨科技(英文) 2023年第3期5卷 350-356页

作者： Jian-Yang Ding Zheng-Tai Liu Zhe Huang Zhi-Cheng Jiang Yi-Chen Yang Zhong-Hao Liu Ji-Shan Liu Yan-Feng Guo da-wei shen State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China

Layered transition metal dichalcogenides have novel physical properties and great potential for *** them,WTe2,which has an extremely large unsaturated magnetoresistance and is theoretically predicted to be a type-Ⅱ Weyl semimetal,has been extensively ***,we systematically probe the electronic structure of WTe_(2) at room temperature using high-resolution angle-resolved photoelectron spectroscopy(ARPES).We find that temperature-driven chemical potential shift and Lifshitz transition,which is equivalent to low-energy band structures shift downward by around 50 meV,compared to the results at low *** ARPES experimental results match well with previous theoretical calculations,implying the possible existence of type-Ⅱ Weyl points near the Γ-X ***,as expected,there exists a dominantly electron-like Fermi surface instead of the one with compensated electrons and ***,our ARPES results show that the flat band(FB) lying below the Fermi level(EF) becomes closer to the Fermi level at room temperature,which might start to dominate the transport behavior and lead to the disappearance of the unsaturated giant magnetoresistance *** findings not only reveal the electronic structure features of WTe_(2) at room temperature,but also provide new insights into the development of room-temperature topological quantum devices.

关键词： Weyl semimetal Electronic structure ARPES Compensation effect

Physics of cavitation near particles

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Journal of Hydrodynamics 2024年第1期36卷 102-118页

作者： Jia-xin Yu Xiao-yu Wang Jun-wei shen Jin-sen Hu Xiang-qing Zhang da-qing He Yu-ning Zhang Key Laboratory of Power Station Energy Transfer Conversion and System(Ministry of Education) School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

The combined effect of cavitation and silt abrasion presents a great challenge and threat to secure the operation and the efficiency of hydraulic machineries working in sediment-laden *** present paper critically reviews the current research progress on the interaction mechanisms of the bubbles and the ***,the analytical models including boundary treatment methods for predicting the jet dynamics of the bubble collapse near particles are ***,the bubble collapsing dynamics,jet dynamics and shock wave characteristics near particles are revealed both experimentally and ***,the bubble-particle-wall system is investigated with a focus on microjets.

关键词： Cavitation bubble particle jet shock wave

Novel Adaptive Memory Event-Triggered-Based Fuzzy Robust Control for Nonlinear Networked Systems via the Differential Evolution Algorithm

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IEEE/CAA Journal of Automatica Sinica 2024年第8期11卷 1836-1848页

作者： wei Qian Yanmin Wu Bo shen School of Electrical Engineering and Automation Henan Polytechnic UniversityJiaozuo 454000China College of Information Science and Technology Donghua UniversityShanghai 201620China

This article mainly investigates the fuzzy optimization robust control issue for nonlinear networked systems characterized by the interval type-2(IT2)fuzzy technique under a differential evolution *** provide a more reasonable utilization of the constrained communication channel,a novel adaptive memory event-triggered(AMET)mechanism is developed,where two event-triggered thresholds can be dynamically adjusted in the light of the current system information and the transmitted historical *** conditions with less conservative design of the fuzzy imperfect premise matching(IPM)controller are presented by introducing the Wirtinger-based integral inequality,the information of membership functions(MFs)and slack ***,under the IPM policy,a new MFs intelligent optimization technique that takes advantage of the differential evolution algorithm is first provided for IT2 TakagiSugeno(T-S)fuzzy systems to update the fuzzy controller MFs in real-time and achieve a better system control ***,simulation results demonstrate that the proposed control scheme can obtain better system performance in the case of using fewer communication resources.

关键词： Adaptive memory event-triggered(AMET) differential evolution algorithm fuzzy optimization robust control interval type-2(IT2)fuzzy technique.

Wireless multisite sensing systems for continuous physiological monitoring

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Science China Materials 2024年第6期67卷 2045-2047页

作者： Ruilai wei Qilin Hua Guozhen shen School of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing 100081China Institute of Flexible Electronics Beijing Institute of TechnologyBeijing 102488China

Respiratory diseases rank as the third leading cause of adult mortality[1],while cardiopulmonary and gastrointestinal issues are the primary cause of death within the first five years of a child’s life[2].The monitoring of cardiac,respiratory,and gastrointestinal sounds plays a vital role in routine care,as alterations or absence of these body sounds can serve as indicators of underlying diseases.

关键词： routine continuous monitoring

High-performance sodium storage for cobalt phosphide composite array electrodes

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Rare Metals 2024年第8期43卷 3724-3734页

作者： Man Zhang Xiao-Xu Liu Tian-Yi Ji Yang Li da-wei sheng Shao-Dong Li Pei-Pei Ren Ze-Xiang shen School of Material Science and Engineering Shaanxi University of Science and TechnologyXi'an 710021China School of Physical and Mathematical Sciences Nanyang Technological UniversitySingapore 637371Singapore

Transition metal phosphides hold great potential as sodium-ion batteries anode materials owing to their high theoretical capacity and modest ***,volume changes and low intrinsic conductivity seriously largely hinder the further development of metal phosphide *** design of phosphide anode materials with reasonable structure is conducive to solving the problems of volume expansion and slow reaction kinetics during the *** this work,a composite material integrating zeolite imidazolate backbone(ZIF) and carbon materials was synthesized by the original growth ***,by the oxidation-phosphating process,CoP nanoarray composites riveted to carbon fiber(CoP@CF) were *** the CoP@CF,CoP nanoparticles are uniformly distributed on ZIF-derived carbon,reducing agglomeration and volume change during *** also provides a highly conductive network for the active material,improving the electrode ***,when evaluated as an anode for sodium-ion batteries,CoP@CF electrode displays enhanced reversible capacity(262 mAh·g^(-1) at 0.1 A·g^(-1)after 100 cycles),which is much better than that of pure CF electrode(57 mAh·g^(-1) at 0.1 A·g^(-1) after 100 cycles)prepared without the addition of *** rate performance of CoP@CF electrode is also superior to that of pure CF electrode at various current densities from 0.05 to1 A·g^(-1).The sodium storage behavior of CoP@CF was revealed by ex-situ X-ray photoelectron spectroscopy,X-ray diffraction,and synchrotron radiation absorption *** method provides a reference for the design and synthesis of anode materials in sodium-ion batteries.

关键词： Cobalt phosphide Array structure Freestanding anodes Sodium-ion batteries

Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 445-454页

作者： Li Yuchun shen Chao Liu wei Li Dong Department of Hydraulic Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this *** auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on *** parametric vibration equation is established for the test model using the finite-element *** auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent *** effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test *** with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental *** a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric *** with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

关键词： auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd Bridge