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Level pinning of anti-PT-symmetric circuits for efficient wireless power transfer

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National Science Review 2024年第1期11卷 215-224页

作者： Zhiwei Guo Fengqing Yang Haiyan Zhang Xian Wu Qiong Wu Kejia Zhu Jun Jiang Haitao Jiang Yaping Yang Yunhui Li Hong Chen MOE Key Laboratory of Advanced Micro-Structured Materials School of Physics Sciences and Engineering Tongji University Department of Electrical Engineering Tongji University school of Automotive studies Tongji University

Wireless power transfer(WPT) technology based on magnetic resonance(a basic physical phenomenon)can directly transfer energy from the source to the load without wires and other physical contacts, and has been successfully applied to implantable medical devices, electric vehicles, robotic arms and other ***, due to the frequency splitting of near-field coupling, the resonant WPT system has some unique limitations, such as poor transmission stability and low efficiency. Here, we propose anti-resonance with level pinning for high-performance WPT. By introducing the anti-resonance mode into the basic WPT platform, we uncover the competition between dissipative coupling and coherent coupling to achieve novel level pinning, and construct an effective anti-parity-time(anti-PT)-symmetric non-Hermitian system that is superior to previous PT-symmetric WPT schemes. On the one hand, the eigenvalue of the anti-PT-symmetric system at resonance frequency is always pure real in both strong and weak coupling regions, and can be used to overcome the transmission efficiency decrease caused by weak coupling, as brought about by, for example, a large size ratio of the transmitter to receiver, or a long transmission *** the other hand, due to the level pinning effect of the two kinds of coupling mechanisms, the working frequency of the system is guaranteed to be locked, so frequency tracking is not required when the position and size of the receiver change. Even if the system deviates from the matching condition, an efficient WPT can be realized, thereby demonstrating the robustness of the level pinning. The experimental results show that when the size ratio of the transmitter coil to the receiver coil is 4.29(which is in the weak coupling region), the transfer efficiency of the anti-PT-symmetric system is nearly 4.3(3.2) times higher than that of the PT-symmetric system when the matching conditions are satisfied(deviated). With the miniaturization and integration of d

关键词： non-Hermitian system wireless power transfer anti-PT-symmetric circuits synthetic dimension metamaterials

Text Reasoning Chain Extraction for Multi-Hop Question Answering

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Tsinghua Science and Technology 2024年第4期29卷 959-970页

作者： Pengming Wang Zijiang Zhu Qing Chen Weihuang Dai school of Data Science and Artificial Intelligence Wenzhou University of TechnologyWenzhou 325035China school of Computer Science and also with Institute of Intelligent Information ProcessingSouth China Business CollegeGuangdong University of Foreign StudiesGuangzhou 510545China school of Psychology Jiangxi Normal UniversityNanchang 330022China also with school of Science East China Jiaotong UniversityNanchang 330013China Institute of Intelligent Information Processing South China Business CollegeGuangdong University of Foreign StudiesGuangzhou 510545China

With the advent of the information age, it will be more troublesome to search for a lot of relevant knowledge to find the information you need. Text reasoning is a very basic and important part of multi-hop question and answer tasks. This paper aims to study the integrity, uniformity, and speed of computational intelligence inference data capabilities. That is why multi-hop reasoning came into being, but it is still in its infancy, that is, it is far from enough to conduct multi-hop question and answer questions, such as search breadth, process complexity, response speed, comprehensiveness of information, etc. This paper makes a text comparison between traditional information retrieval and computational intelligence through corpus relevancy and other computing methods. The study finds that in the face of multi-hop question and answer reasoning, the reasoning data that traditional retrieval methods lagged behind in intelligence are about 35% worse. It shows that computational intelligence would be more complete, unified, and faster than traditional retrieval methods. This paper also introduces the relevant points of text reasoning and describes the process of the multi-hop question answering system, as well as the subsequent discussions and expectations.

关键词： intelligent computing multi-hop quiz text reasoning document retrieval text complex network

Global existence and large-time behavior for primitive equations with the free boundary

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Science China Mathematics 2024年第10期67卷 2303-2330页

作者： Hai-Liang Li Chuangchuang Liang school of Mathematical Sciences Capital Normal University Academy for Multidisciplinary studies Capital Normal University College of Mathematics and Statistics Chongqing University

In the present paper, the primitive equations, which can be used to simulate the large-scale motion of the ocean and atmosphere, are considered in the three-dimensional domain bounded below by a fixed solid boundary and above by a free-moving boundary. The global existence and uniqueness of strong solutions are established, and the long-time convergence to the equilibrium state is shown to be either at an exponential rate for the horizontal periodic domain or at an algebraic rate for the horizontal whole space.

关键词： primitive equations the free boundary value problem global well-posedness large-time behavior

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Whose Aid is Beneficial to Firms'Exports?Evidence from a Post-disaster Aid Experiment in China

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China & World Economy 2024年第2期32卷 73-96页

作者： Tan Li Qing Liu Lihe Xu school of International Business Southwestern University of Finance and EconomicsChina school of Economics Renmin University of ChinaChina Institute of studies for the Greater Bay Area Guangdong University of Foreign StudiesChina

Post-disaster aid is widely regarded as important in helping local recovery and *** paper examines the effectiveness of post-disaster aid on exports,which are a driving factor of economic *** reports a natural experiment in China–the case of post-disaster aid following the Wenchuan earthquake in 2008–to examine how donors'experiences affected the exports of manufacturing firms in disaster-stricken *** export experience of the donor was *** coming from donors with more export experience was more beneficial to the exports of firms in recipient counties than aid from less experienced donors.“Learning from the donor”is a potential channel through which this effect *** is,firms in recipient counties learned from donors'export experience by exporting more products similar to those of donors,exporting more to the destination countries of donors,and participating in the donors'supply-chain networks by exporting more of the donors'***“learning from the donor”effects show that knowledge spillover can occur between spatially distant parties,which complements the literature.

关键词： China export knowledge spillover post-disaster aid

Influence of Mixture Gas Conditions on the Laminar Combustion Characteristics of Natural Gas

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Journal of Thermal Science 2024年第3期33卷 1231-1241页

作者： LOU Diming ZHU Kan ZHANG Yunhua REN Yedi TAN Piqiang FANG Liang FAN Lanlan school of Automotive studies Tongji UniversityShanghai201804China Ji’nan Power Co.Ltd Sinotruk GroupJi’nan250200China

Natural gas is a promising alternative fuel for the internal combustion engine,and natural gas engine has become an efficient and feasible measure to deal with the energy shortage and climate *** the laminar flame characteristics are the foundation of the turbulent flame,the laminar flame characteristics of natural gas have a significant impact on the combustion status and efficiency of the engine.A visual constant volume bomb was used to study the influence of the gas components,different excess air coefficient(λ),and initial conditions on the laminar combustion characteristics of natural *** experimental results showed that when the initial pressure and temperature were 0.1 MPa and 300 K respectively,compared to propane,ethane had a remarkable influence on the equivalent-combustion laminar-combustion-speed,with an average increase of approximately 5.1%for every 2.5%increase in the ethane *** laminar combustion velocity of the natural gas under different excess air coefficients had a maximum value at aboutλ=1.0,and the Markstein length of the flame decreased with the increase of theλ.The increase in the initial pressure of the mixture resulted in a decrease in the equivalent-combustion laminar-combustion-speed of the flame,a significant decrease in the Markstein *** increase of the initial temperature of the mixture led to a rapid increase of the equivalent-combustion laminar-combustion-speed,but the effect on the flame Markstein length was not dominant.

关键词： constant volume bomb natural gas engine combustion characteristics laminar combustion velocity Markstein length

Development of advanced anion exchange membrane from the view of the performance of water electrolysis cell

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Journal of Energy Chemistry 2024年第3期90卷 348-369,I0009页

作者： Chao Liu Zhen Geng Xukang Wang Wendong Liu Yuwei Wang Qihan Xia Wenbo Li Liming Jin Cunman Zhang Clean Energy Automotive Engineering Center Tongji UniversityShanghai 201804China school of Automotive studies Tongji UniversityShanghai 201804China

Green hydrogen produced by water electrolysis combined with renewable energy is a promising alternative to fossil fuels due to its high energy density with zero-carbon *** water electrolysis technologies,the anion exchange membrane(AEM) water electrolysis has gained intensive attention and is considered as the next-generation emerging technology due to its potential advantages,such as the use of low-cost non-noble metal catalysts,the relatively mature stack assembly process,***,the AEM water electrolyzer is still in the early development stage of the kW-level stack,which is mainly attributed to severe performance decay caused by the core component,i.e.,***,the review comprehensively presents the recent progress of advanced AEM from the view of the performance of water electrolysis ***,fundamental principles and critical components of AEM water electrolyzers are introduced,and work conditions of AEM water electrolyzers and AEM performance improvement strategies are *** challenges and perspectives are also analyzed.

关键词： Hydrogen Water electrolysis Anion exchange membrane Electrolysis cell

A historical overview of nano-optics:From near-field optics to plasmonics

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Chinese Physics B 2024年第5期33卷 134-145页

作者：邓妙怡朱星 Department of History of Science Technology and MedicineAcademy for Advanced Interdisciplinary StudiesPeking UniversityBeijing 100871China school of Physics Peking UniversityBeijing 100871China

Nano-optics is an emergent research field in physics that appeared in the 1980s,which deals with light–matter optical interactions at the nanometer *** early studies of nano-optics,the main concern focus is to obtain higher optical resolution over the diffraction *** researches of near-field imaging and spectroscopy based on scanning near-field optical microscopy(SNOM)are *** exploration of improving SNOM probe for near-field detection leads to the emergence of surface *** the sense of resolution and wider application,there has been a significant transition from seeking higher resolution microscopy to plasmonic near-field modulations in the nano-optics community during the nano-optic ***,studies of nano-optics prefer the investigation of plasmonics in different material *** this article,the history of the development of near-field optics is briefly *** difficulties of conventional SNOM to achieve higher resolution are *** an alternative solution,surface plasmons have shown the advantages of higher resolution,wider application,and flexible nano-optical modulation for new *** typical studies in different periods are introduced and characteristics of nano-optics in each stage are *** this way,the evolution progress from near-field optics to plasmonics of nano-optics research is *** future development of nano-optics is discussed then.

关键词： nano-optics near-field optics surface plasmon plasmonic modulation

Realizing quantum imaginary time evolution in experiment

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 167-168页

作者： Xiao Yuan Center on Frontiers of Computing studies Peking UniversityBeijing 100871China school of Computer Science Peking UniversityBeijing 100871China

NISQ,or Noisy Intermediate-Scale Quantum computing,represents a pivotal and the state-of-the-art quantum technology[1].Characterized by intermediate-scale quantum devices that are beyond classical computational capabilities yet fall short of the error-correction thresholds required for fault-tolerant quantum computing,NISQ devices exhibit both promise and *** devices hold immense potential in solving certain computational problems that surpass classical capabilities,with wide applications in optimization,machine learning,and quantum chemistry.

关键词： quantum imaginary correction

From the dust:extracellular vesicles as regulators of development and neuroregeneration

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Neural Regeneration Research 2024年第5期19卷 933-934页

作者： Leon G.Coleman Jr The University of North Carolina at Chapel Hill School of MedicineDepartment of PharmacologyBowles Center for Alcohol StudiesChapel HillNCUSA

First impressions can have a lasting *** science,this can be especially problematic,because our lack of understanding often causes us to mislabel and thus ignore important biological *** this vein,extracellular vesicles(EVs)were once considered to be“cellular dust”.Similar to the previous concept of“junk DNA”to describe protein non-coding regions,EVs are far more than just cellular *** fact,EVs are emerging as key mediators of intracellular communication across nearly all biological *** includes peripheral immune responses(e.g.,arthropathies and sepsis),intra-organ communication(Seim et al.,2023),and a host of other physiological and pathological states(Figure 1A and B).

关键词： Figure extracellular