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Nonlinearity-enabled higher-order exceptional singularities with ultra-enhanced signal-to-noise ratio

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National Science Review 2023年第7期10卷 98-106页

作者： Kai bai Liang Fang tian-Rui Liu Jia-Zheng Li Duanduan Wan Meng Xiao Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and Technology Wuhan University Wuhan Institute of Quantum Technology

Higher-order exceptional points(HOEPs) with extraordinary responsivity are expected to exhibit a vastly improved performance in detection-related ***,over the past few years,such an approach has been questioned due to several potential drawbacks,including the stringent parameter re quirements,fundamental resolution limits and ***,exploring the conse quence of nonlinear gain saturation in exceptional singularities of non-Hermitian systems,we offer a feasible scheme to overcome all the above *** provide a simple and intuitive example by demonstrating with both theory and circuit experiments an ’exceptional nexus’(’EX’),a HOEP with an ultra-enhanced signal-to-noise ratio(SNR),in only two coupled resonators with the aid of nonlinear *** tedious parameter tuning in a six-dimensional hyper-dimensional space is reduced to two *** feedback mechanism of nonlinear saturable gain can give a solution to the ongoing debate on the SNR of EPs in other linear *** findings advance the fundamental understanding of the peculiar topology of nonlinear non-Hermitian systems,significantly reduce the practical difficulty in EP sensing and possibly open new avenues for applications.

关键词： higher-order exceptional point nonlinearity ultra-enhanced signal-to-noise ratio

Preparation of Clay/Biochar Composite Adsorption Particle and Performance for Ammonia Nitrogen Removal from Aqueous Solution

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Journal of Ocean University of China 2020年第3期19卷 729-739页

作者： HUANG Xiao bai Jie LI Kuiran ZHAO Yangguo tian Weijun HU Chunhui College of Environmental Science and Engineering Ocean University of ChinaQingdao 266100China College of Marine Life Science Ocean University of ChinaQingdao 266003China Nanjing University of Information Science and Technology Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologyJiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution ControlNanjing 210044China

This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen(NH4^+-N) from micro-contaminated water. The removal performance of NH4^+-N by composite adsorption particle was monitored under different raw material proportions and initial NH4^+-N concentration. Besides, adsorption kinetics and adsorption isotherms were investigated to reveal the adsorption mechanisms. The results showed that NH4^+-N was effectively removed under optimal proportion of biochar, foaming agent and crosslinker with 20%, 3%, and 3%, respectively. The optimal contact time was 150 min and the best removal efficiency was 88.6% at initial NH4^+-N concentration of 20 mg L^-1. The adsorption performance was well described by the second order kinetic model and Freundlich model. The novel clay/biochar composite adsorption particle in this study demonstrated a high potential for NH4^+-N removal from surface water.

关键词： clay biochar composite adsorption particle ammonia nitrogen removal adsorption mechanism

Experiment and modelling of texture and sliding direction dependence on finger friction behavior

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Friction 2024年第9期12卷 1955-1968页

作者： Yuanzhe LI Xue ZHOU Pengpeng bai Zhonghuan XIANG Yonggang MENG Liran MA Yu tian State Key Laboratory of Tribology in Advanced Equipment School of Mechanical EngineeringTsinghua UniversityBeijing 100084China

Humans rely on their fingers to sense and interact with external *** the tribological behavior between finger skin and object surface is crucial for various fields,including tactile perception,product appearance design,and electronic skin *** describing finger frictional behavior is always challenging,given the complex structure of the *** this study,the texture and sliding direction dependence of finger skin friction was quantified based on explicit mathematic *** proposed double-layer model of finger skin effectively described the nonlinear elastic response of skin and predicted the scaling-law of effective elastic modulus with contact ***,the skin friction model on textured surface considering adhesion and deformation factors was *** revealed that adhesive term dominated finger friction behavior in daily life,and suggested that object texture size mainly influenced friction-induced vibrations rather than the average friction *** with digital image correlation(DIC)technique,the effect of sliding direction on finger friction was *** was found that the anisotropy in finger friction was governed by the finger’s ratchet pawl structure,which also contributes to enhanced stick-slip vibrations in the distal sliding *** proposed friction models can offer valuable insights into the underlying mechanism of skin friction under various operating conditions,and can provide quantitative guidance for effectively encoding friction into haptics.

关键词： finger friction tactile perception tribological model textured surface sliding direction

The Rapid Assessment and Early Warning Models for COVID-19

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Virologica Sinica 2020年第3期35卷 272-279页

作者： Zhihua bai Yue Gong Xiaodong tian Ying Cao Wenjun Liu Jing Li CAS Key Laboratory of Pathogenic Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China National Science Library Chinese Academy of SciencesBeijing 100190China Institute of Microbiology Center for Biosafety MegaScienceChinese Academy of SciencesBeijing 100101China

Human beings have experienced a serious public health event as the new pneumonia(COVID-19), caused by the severe acute respiratory syndrome coronavirus has killed more than 3000 people in China, most of them elderly or people with underlying chronic diseases or immunosuppressed states. Rapid assessment and early warning are essential for outbreak analysis in response to serious public health events. This paper reviews the current model analysis methods and conclusions from both micro and macro perspectives. The establishment of a comprehensive assessment model, and the use of model analysis prediction, is very efficient for the early warning of infectious diseases. This would significantly improve global surveillance capacity, particularly in developing regions, and improve basic training in infectious diseases and molecular epidemiology.

关键词： COVID-19 SARS-CoV-2 Models Rapid assessment Early warning

Systolic B-1 Circuit in Galois Fields Based on a Quaternary Logic Technique

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Journal of Beijing Institute of Technology 2020年第2期29卷 177-183页

作者： Haixia Wu Yilong bai tian Wang Xiaoran Li Long He School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China

In order to improve the circuit complexity and reduce the long latency of B-1 operations,a novel B-1 operation in Galois Field GF(24)is presented and the corresponding systolic realization based on multiple-valued logic(MVL)is *** systolic structure employs multiplevalued current mode(MVCM)by using dynamic source-coupled logic(SCL)to reduce the initial delay and the transistor and wire *** performance is evaluated by HSPICE simulation in 0.18μm CMOS technology and a comparison is conducted between our proposed implementation and those reported in the *** initial delay and the sum of transistors and wires in our MVL design are about 43%and 13%lower,respectively,in comparison with other corresponding binary CMOS *** systolic architecture proposed is simple,regular,and modular,well suited for very large scale integration(VLSI)*** combination of MVCM circuits and relevant algorithms based on MVL seems to be a potential solution for high performance arithmetic operations in GF(2k).

关键词： multiple-valued logic(MVL) systolic B^-1 circuit Galois Fields

BERST: An Engine and Tool for Exploring Biomedical Entities and Relationships

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Chinese Journal of Electronics 2019年第4期28卷 797-804页

作者： bai tian GE Yan YANG Changqing LIU Xiaohua GONG Leiguang WANG Ye HUANG Lan College of Computer Science and Technology Jilin University Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University Department of Computer Science and Technology Zhuhai College of Jilin University

To facilitate the search of rapidly growing biomedical knowledge in literature, we developed a Biomedical entity-relationship search tool(BERST). It is also a biomedical knowledge integration framework, which presently contains six popular databases represented in terms of a network of concepts and relations extracted from these knowledge sources. Users search the integrated knowledge network by entering keywords, and BERST returns a sub-network matching and representing the keywords and their relationships. The resulting graph can be navigated interactively allowing users to explore specific paths between any two nodes representing potentially interesting relationships between them. A graphical UI was developed to provide a more intuitive and overall view of the information being searched and studied. BERST framework can be naturally expanded to integrate other biomedical knowledge sources. BERST is implemented as a Java web application.

关键词： Biomedical ontology Relationship mining Relationship searching tool

Mapping the magnetic field in the solar corona through magnetoseismology

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Science China(Technological Sciences) 2020年第11期63卷 2357-2368页

作者： YANG ZiHao tian Hui TOMCZYK Steven MORTON Richard bai XianYong SAMANTA Tanmoy CHEN YaJie School of Earth and Space Sciences Peking UniversityBeijing 100871China Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China High Altitude Observatory National Center for Atmospheric ResearchBoulderCO 80307USA Department of Mathematics Physics and Electrical EngineeringNorthumbria UniversityNewcastle Upon Tyne NE18STUK Department of Physics and Astronomy George Mason UniversityFairfaxVA 22030USA Johns Hopkins University Applied Physics Laboratory LaurelMD 20723USA Max Planck Institute for Solar System Research 37077 G¨ottingenGermany

Magnetoseismology,a technique of magnetic field diagnostics based on observations of magnetohydrodynamic(MHD)waves,has been widely used to estimate the field strengths of oscillating structures in the solar ***,previously magnetoseismology was mostly applied to occasionally occurring oscillation events,providing an estimate of only the average field strength or one-dimensional distribution of field strength along an oscillating *** restriction could be eliminated if we apply magnetoseismology to the pervasive propagating transverse MHD waves discovered with the Coronal Multi-channel Polarimeter(CoMP).Using several CoMP observations of the Fe xiii 1074.7 nm and 1079.8 nm spectral lines,we obtained maps of the plasma density and wave phase speed in the corona,which allow us to map both the strength and direction of the coronal magnetic field in the plane of *** also examined distributions of the electron density and magnetic field strength,and compared their variations with height in the quiet Sun and active *** measurements could provide critical information to advance our understanding of the Sun's magnetism and the magnetic coupling of the whole solar atmosphere.

关键词： solar corona solar magnetic field waves magnetoseismology

基于分子动力学研究纳米孔洞对多晶FeO/Fe中FeO断裂的影响

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原子与分子物理学报 2025年第5期42卷 81-89页

作者：龚建雄周存龙郭瑞柴泽琳孟钰峰王天翔太原科技大学机械工程学院、山西省冶金设备设计理论与技术重点实验室太原030024 山西太钢不锈钢精密带钢有限公司太原030024

孔洞缺陷是影响表面氧化皮断裂失效的重要因素.本文结合分子动力学软件Lammps和Atomsk软件建立了半径相同位置不同(模型1)和孔洞位置相同半径不同(模型2)两种模型,为了探究两者对FeO/Fe多晶模型拉伸失效的影响,文章从抗拉强度、断裂韧... 详细信息

孔洞缺陷是影响表面氧化皮断裂失效的重要因素.本文结合分子动力学软件Lammps和Atomsk软件建立了半径相同位置不同(模型1)和孔洞位置相同半径不同(模型2)两种模型,为了探究两者对FeO/Fe多晶模型拉伸失效的影响,文章从抗拉强度、断裂韧性、中心对称参数(CSP)三方面进行了分析,模拟结果表明:1.当孔洞位于晶界和三叉点时,模型1和2的抗拉强度随着孔洞半径的增大而减小,断裂韧性在抗拉强度降低的同时增强.2.孔洞位于晶内时,模型2的抗拉强度呈现“先下降-后上升-再下降”的变化趋势,断裂韧性整体降低;模型1既增强了模型的抗拉强度,又降低了断裂韧性.3.裂纹扩展受孔洞半径影响较大,半径达到1 nm以上时,模型2的裂纹扩展速度加快,模型1的裂纹扩展速度减慢.本研究为进一步认识氧化皮的断裂过程提供了帮助.

关键词：分子动力学多晶FeO/Fe 预制孔洞抗拉强度断裂韧性

Application of a Magnetic-field-induced Transition in Fe X to Solar and Stellar Coronal Magnetic Field Measurements

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Research in Astronomy and Astrophysics 2023年第2期23卷 1-17页

作者： Yajie Chen Wenxian Li Hui tian Xianyong bai Roger Hutton Tomas Brage School of Earth and Space Sciences Peking UniversityBeijing 100871China Max Planck Institute for Solar System Research Gottingen D-37077Germany National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Department of Astronomy Beijing Normal UniversityBeijing 100875China Division of Mathematical Physics Lund UniversityPO Box 118sE-22100 LundSweden

Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other *** and accurate measurements of the magnetic fields at all the atmospheric layers are of critical importance to understand these magnetic activities,but in the solar and stellar coronae such a measurement is still a challenge due to the weak field strength and the high ***,a magnetic-field-induced transition(MIT)of Fe X at 257.26A has been proposed for the magnetic field measurements in the solar and stellar *** this review,we present an overview of recent progresses in the application of this method in *** start by introducing the theory underlying the MIT method and reviewing the existing atomic data critical for the spectral modeling of Fe X *** also discuss the laboratory measurements that verify the potential capability of the MIT technique as a probe for diagnosing the plasma magnetic *** then continue by investigating the suitability and accuracy of solar and stellar coronal magnetic field measurements based on the MIT method through forward ***,we discuss the application of the MIT method to the existing spectroscopic observations obtained by the Extreme-ultraviolet Imaging Spectrometer onboard *** novel technique provides a possible way for routine measurements of the magnetic fields in the solar and stellar coronae,but still requires further efforts to improve its ***,the challenges and prospects for future research on this topic are discussed.

关键词： Sun corona-Sun magnetic fields-Sun UV radiation