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Asymmetric chlorophyll responses enhanced by internal waves near the Dongsha Atoll in the South china Sea

Journal of Oceanology and Limnology 2023年第2期41卷 418-426页

作者： Meilin WU Huijie XUE Fei chai State Key Laboratory of Marine Environmental Science College of Ocean and Earth SciencesXiamen UniversityXiamen 361102China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering guangdong Laboratory(guangzhou) Guangzhou 511458China Innovation Academy of South china Sea Ecology and Environmental Engineering Chinese Academy of SciencesGuangzhou 510301China

Internal waves(IWs)are small-scale physical processes that occur frequently in stratified marginal *** are ubiquitous and well documented in the northern South china Sea(n ScS),but few studies have explored the ecosystem responses to the *** chlorophyll-a(chl-a)data from 2002 to 2014 were used to examine the distribution of chl a near the Dongsha Atoll(DSA).composite chl a from about 40 IWs during spring and summer showed stronger response on the northern side than on the southern side of the *** day after the passage of IWs,composite surface chl a on the northern side increased from 0.11 mg/m3 to a maximum mean value of 0.18 mg/*** decreased to 0.13 mg/m3 after two days and maintained that level for several days after the passage of *** enhanced surface chl a likely caused subsurface chl-a maximum and nutrients in the surface *** 64%of the increase in surface chl a was due to the uplift of the subsurface chl-a maximum one day after the passage of IWs,while nutrient-induced new phytoplankton growth contributed about 18%of the increase a few days *** the IWs occurred frequently in spring and summer,chl-a level on the northern side was about 30%higher than that on the southern *** dissipation and its impact on nutrients and chlorophyll were stronger on the northern side of the DSA than on the south,which caused a north-south asymmetric distribution of chl a in the region.

关键词： internal waves(IWs) phytoplankton nutrients Dongsha Atoll northern South china Sea

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Separability for Positive Operators on Tensor Product of Hilbert Spaces

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Acta Mathematica Sinica,English Series 2021年第6期37卷 893-910页

作者： Jin chuan HOU Jin Fei chai college of Mathematics Taiyuan University of TechnologyTaiyuan 030024P.R.China

The separability and the entanglement(that is,inseparability)of the composite quantum states play important roles in quantum information ***,a quantum state is a trace-class positive operator with trace one acting on a complex separable Hilbert *** this paper,in more general frame,the notion of separability for quantum states is generalized to bounded positive operators acting on tensor product of Hilbert ***,not like the quantum state case,there are different kinds of separability for positive operators with different operator *** types of such separability are discussed;several criteria such as the finite rank entanglement witness criterion,the positive elementary operator criterion and PPT criterion to detect the separability of the positive operators are established;some methods to construct separable positive operators by operator matrices are *** may also make us to understand the separability and entanglement of quantum states better,and may be applied to find new separable quantum states.

关键词： Hilbert spaces tensor products positive operators separability entanglement

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Semi-supervised community detection on attributed networks using non-negative matrix tri-factorization with node popularity

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Frontiers of computer Science 2021年第4期15卷 61-71页

作者： Di JIN Jing HE Bianfang chai Dongxiao HE college of Intelligence and computing Tianjin UniversityTianjin 300350China Department of Information Engineering Hebei GEO UniversityShijiazhuang 050031China

The World Wide Web generates more and more data with links and node contents,which are always modeled as attributed *** identification of network communities plays an important role for people to understand and utilize the semantic functions of the data.A few methods based on non-negative matrix factorization(NMF)have been proposed to detect community structure with semantic information in attributed ***,previous methods have not modeled some key factors(which affect the link generating process together),including prior information,the heterogeneity of node degree,as well as the interactions among *** three factors have been demonstrated to primarily affect the *** this paper,we propose a semi-supervised community detection method on attributed networks by simultaneously considering these three ***,a semi-supervised non-negative matrix tri-factorization model with node popularity(i.e.,PSSNMTF)is designed to detect communities on the topology of the *** then node contents are integrated into the PSSNMTF model to find the semantic communities more accurately,namely *** of the PSSNMTFc model is estimated by using the gradient descent *** on some real and artificial networks illustrate that our new method is superior over some related stateof-the-art methods in terms of accuracy.

关键词： community detection non-negative matrix trifactorization node popularity attributed networks

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Elastic twisting metamaterial for perfect longitudinal-torsional wave mode conversion

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Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 515-524页

作者： Shengjie YAO Yijun chai Xiongwei YANg Yueming LI State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight VehicleSchool of AerospaceXi’an Jiaotong UniversityXi’an 710049China

In this work,we design a twisting metamaterial for longitudinal-torsional(L-T)mode conversion in pipes through exploring the theory of perfect transmodal FabryPerot interference(TFPI).Assuming that the axial and radial motions in pipes can be decoupled,we find that the metamaterial can be designed in a rectangular coordinate system,which is much more convenient than that in a cylindrical *** calculation with detailed microstructures shows that an efficient L-T mode conversion can be obtained in pipes with different *** addition,we fabricate mode-converting microstructures on an aluminum pipe and conduct ultrasonic experiments,and the results are in good agreement with the numerical *** expect that the proposed LT mode-converting metamaterial and its design methodology can be applied in various ultrasonic devices.

关键词： elastic wave mode conversion elastic metamaterial ultrasonic device

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Botanic gardens should lead the way to create a "garden Earth" in the Anthropocene

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Plant Diversity 2017年第6期39卷 331-337页

作者： charles H.cannon chai-Shian Kua The center for Tree Science The Morton Arboretum Science and conservation The Morton Arboretum Shanghai Engineering Research center for Urban Tree Ecology and Applications

The strength and expertise that botanic gardens bring to conservation are based on their detailed knowledge and understanding of the care. management, and biology of a diversity of plant species. This emphasis on the organism has led to many ex-situ and in-situ conservation programs aimed at protecting endangered species, restoring threatened populations, and establishing living plant and seed collections of endangered species. In china, the scale and pace of change in land and resource use, often leading to environmental degradation, has created a strong emphasis on improving environmental conditions. If done properly, being "green" can be a surprisingly complex issue, because it should encompass and exploit the whole of plant diversity and function. Unfortunately, 'green' often includes a small portion of this whole. Earth's rich plant diversity presents considerable opportunity but requires expertise and knowledge for stable and beneficial management. With the dawning of the Anthropocene, we should strive to live on a "garden Earth", where we design and manage our environments, both built and natural, to create a healthy, beneficial living landscape for people and other organisms. The staff of botanic gardens worldwide and the living collections they maintain embody the best examples of sustainable, beautiful, and beneficial environments that thrive on plant diversity. This expertise should be a fundamental resource for agencies in all sectors responsible for managing and designing "green" infrastructure. Botanic gardens should actively engage and contribute to these opportunities, from large public infrastructure projects to small private conservation efforts. Here, we discuss several ongoing conservation efforts, primarily in china, and attempt to identify areas where botanic gardens could make a significant and meaningful difference.

关键词： green infrastructure Botanic garden Ex-situ conservationln-situ conservation Botanical garden

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Door to the cell for cOVID-19 opened,leading way to therapies

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Signal Transduction and Targeted Therapy 2020年第1期5卷 1514-1515页

作者： Zhiwei Huang Jijie chai center for Life Sciences School of Life Science and TechnologyHarbin Institute of TechnologyHarbin 150080China School of Life Sciences Tsinghua UniversityBeijing 100084China

A very recent study by Lan et al.1 published in Nature determined the crystal structure of the severe acute respiratory syndrome coronavirus(SARS-coV)-2 receptor-binding domain(RBD)bound to angiotensin-converting enzyme 2(AcE2).The structure reveals the mechanism of SARS-coV-2 RBD recognition by its receptor AcE2,which is highly conserved in AcE2 recognition of SARS-coV *** study provides structural information on developing small molecules targeting SARS-coV-2 RBD/AcE2 and implies the existence of other mechanisms than receptor binding for the markedly different infection activity of the two evolutionarily close viruses.

关键词： AcE2 markedly al

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Dynamics and synchronization of a complex-valued star network

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Science china(Technological Sciences) 2021年第12期64卷 2729-2743页

作者： chai Lin LIU Jian cHEN guanRong ZHAO Xiu School of Mathematical Sciences University of JinanJinan 250022China Department of Electrical Engineering City University of Hong KongHong KongChina

complex networks have been extensively investigated in recent ***,the dynamics,especially chaos and bifurcation,of the complex-valued complex network are rarely *** this paper,a star network of coupled complex-valued van der Pol oscillators is proposed to reveal the mechanism of star *** the aid of bifurcation diagram,Lyapunov exponent spectrum and phase portrait in this study,chaos,hyper-chaos,and multi-existing chaotic attractors are observed from the star network,although there are only periodic states in a complex-valued van der Pol *** versus coupling strength and nonlinear coefficient shows that the bigger the network size,the larger the parameter range within the chaotic(hyper-chaotic)*** is revealed that the chaotic bifurcation path is highly robust against the size variation of the star network,and it always evolves to chaos directly from period-1 and quasi-periodic states,***,the coexistence of chaotic phase synchronization and complete synchronization among the peripherals is also found from the star network,which is a symmetrybreaking phenomenon.

关键词： star network chaotic phase synchronization complex-valued van der Pol oscillator symmetry-breaking

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Impacts of close-to-nature management on the stand states of Masson pine forests

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Ecosystem Health and Sustainability 2020年第1期6卷 425-432,424页

作者： Zongzheng chai Wei Tan college of Forestry Guizhou UniversityGuiyangGuizhouPR China

Introduction:Research on the effect of close-to-nature management(cTNM)on stand states and dynamics of forests is crucial for the evaluation of cTNM implemented and sustainable development of ***:We analyzed and compared the stand states and dynamics of Masson pine(Pinus massoniana)plantations in the young,middle-aged,and near-mature stages under cTNM eight years after selective cutting and unmanaged *** paired-sample T-tests and RDA ordination results demonstrated that the overall stand states with cTNM were superior to the control treatment in all three *** interaction of the cTNM and stand age significantly affected The Shannon-Wiener index of diameter class and regeneration *** and conclusion:cTNM and stand age jointly affected the stand state of forests and cTNM accelerated the forest development,which promoted an increase in the heterogeneity of stand parameters and shortened the formation time of a target *** tree size differentiation and adequate regeneration are particularly important aspects for improving the quality of Masson pineforests during the management processes.

关键词： close-to-nature management forest quality stand states development stage

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Estimation of buoy drifting based on adaptive parameter-varying time scale Kalman filter

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Journal of control and Decision 2021年第3期8卷 353-362页

作者： Han Xue Tian chai School of Navigation Jimei UniversityXiamenPeople’s Republic of China National and local joint engineering research center of ship aided navigation technology Jimei UniversityXiamenPeople’s Republic of China Fujian Shipping Research Institute Jimei UniversityXiamenPeople’s Republic of China Xiamen southeast International Shipping Research center Jimei UniversityXiamenPeople’s Republic of China

To solve Kalman filter with dynamic time scale problem,an adaptive parameter-varying time scale kalman filter(APVTS-KF)is *** adaptive mechanism for choosing the covariance of state noise is ***-KF is used to estimate the buoy drifting trajectory with different report *** drifting data of four buoys are used to test the proposed *** influence of report interval,drifting distance,adaptive factor and noise covariance are analysed and *** experimental results and error analysis show that APVTS-KF is better than other algorithms in trajectory ***,Kalman filtering can be used for accurate trajectory estimation in the actual situation of buoy drifting with dynamic time intervals.

关键词： Kalman filter buoy drift state estimation

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Observer-based self-triggered control for time-varying formation of multi-agent systems

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Science china(Information Sciences) 2021年第3期64卷 177-192页

作者： Xiaofeng chai Jian LIU Yao YU changyin SUN School of Automation and Electrical Engineering University of Science and Technology Beijing School of Automation Southeast University

This paper studies the time-varying formation problem of general multi-agent systems with undirected topology via observer-based event-triggered control schemes. The distributed event-triggered control scheme and self-triggered control scheme are developed respectively. Each agent updates its next event time using current information without continuous communication in self-triggered control *** error and state estimation error are considered simultaneously to get more accurate ***, it is only when a request is received that each agent broadcasts its information. It is demonstrated that the time-varying formation can be achieved asymptotically under the two proposed control schemes and Zeno behavior can be excluded. Finally, numerical examples are provided to illustrate the effectiveness of the proposed observer-based event-triggered control strategies.

关键词： multi-agent systems time-varying formation states observer event-triggered

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