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Mechanism of plant-soil feedback in a degraded alpine grassland on the Tibetan Plateau

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JOURNAL OF PLANT ECOLOgY 2024年第2期17卷 188-199页

作者： Zhou, Tiancai sun, Jian Shi, Peili Chinese Acad Sci Inst Geog Sci & Nat Resources Res Key Lab Ecosyst Network Observat & Modelling Beijing 100101 Peoples R China Chinese Acad Sci Inst Tibetan Plateau Res State Key Lab Tibetan Plateau Earth Syst Resources Beijing 100101 Peoples R China Minist Educ Key Lab Biodivers & Environm Qinghai Tibet Plateau Lhasa 850011 Peoples R China Tibet Res Acad Ecoenvironm Sci Lhasa 850000 Peoples R China Univ Chinese Acad Sci Coll Resources & Environm Beijing 100049 Peoples R China

Although biotic and abiotic factors have been confirmed to be critical factors that affect community dynamics, their interactive effects have yet to be fully considered in grassland degradation. Herein, we tested how soil nutrients and microbes regulated plant-soil feedback (PSF) in a degraded alpine grassland. Our results indicated that soil total carbon (STC; from 17.66 to 12.55 g/kg) and total nitrogen (STN; from 3.16 to 2.74 g/kg) exhibited significant (P graded (ND) to severely degraded (SD). Despite higher nutrients in ND soil generating significantly (P growth when the soil was sterilized, a high proportion of pathogens (36%) in ND non-sterilized soil resulted in a strong negative PSF on monocots. In contrast, the higher phenotypic plasticity of dicots coupled with a higher abundance of mutualists and saprophytes (70%) strongly promoted their survival and growth in SD with infertile soil. Our findings identified a novel mechanism that there was a functional group shift from monocots with higher vulnerability to soil pathogens in the ND fertile soil to dicots with higher dependence on nutritional mutualists in the degraded infertile soil. The emerging irreversible eco-evolutionary in PSF after degradation might cause a predicament for the restoration of degraded grassland.

关键词： plant-soil feedback plant function groups degradation alpine grassland Tibetan Plateau LITTER DECOMPOSITION COMMUNITY TRAITS DIVERSITY COMPETITION DEPENDENCE ECOSYSTEM DYNAMICS DRIVERS CARBON

An Accurate Numerical Scheme for Mean-Field Forward and Backward SDEs with Jumps

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NUMERICAL MATHEMATICS-THEORY METHODS AND APPLICATIONS 2024年第1期17卷 243-274页

作者： sun, Yabing Yang, Jie Zhao, Weidong Natl Univ Def Technol Coll Sci Changsha 410073 Peoples R China Shandong Univ Sch Math & Stat Weihai 264209 Peoples R China Shandong Univ Sch Math Jinan 250100 Peoples R China

In this work, we propose an explicit second order scheme for decoupled mean-field forward backward stochastic differential equations with jumps. The stability and the rigorous error estimates are presented, which show that the proposed scheme yields a second order rate of convergence, when the forward mean-field stochastic differential equation is solved by the weak order 2.0 Ito-Taylor scheme. Numerical experiments are carried out to verify the theoretical results.

关键词： Mean-field forward backward stochastic differential equation with jumps stability analysis error estimates STOCHASTIC DIFFERENTIAL-EQUATIONS QUADRATIC OPTIMAL-CONTROL MAxIMUM PRINCIPLE MCKEAN-VLASOV gAMES

Distributed swarm control for multi-robot systems inspired by shepherding behaviors

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Science China(Technological Sciences) 2024年第7期67卷 2191-2202页

作者： sun guiBin gU HaiBo LÜJinHu School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Zhongguancun Laboratory Beijing 100094China

Swarming behaviors play an eminent role in both biological and engineering research, and show great potential applications in many emerging fields. Traditional swarming models still lack integrity, uniformity, and stability in swarm forming processes,resulting in fragmentation and void phenomena. Inspired by the shepherding behaviors observed in nature, we propose an integrated negotiation-control scheme for distributed swarm control of massive robots. The core idea of this scheme is that the robots at the boundary of the group herd the internal robots to form an equilibrium swarm. For this purpose, we introduce a concept of virtual group center towards which boundary robots herd internal robots. Then, a distributed negotiation mechanism is designed to allow each robot to negotiate the virtual group center only through local interactions with its neighbors. After that, we propose a shepherding-inspired swarm control law to drive a group of robots to form an integrated, uniform, and stable configuration from any initial states. Both numerical and flight simulations are presented to verify the effectiveness of our proposed swarm control scheme.

关键词： swarm control multi-robot system negotiation-control scheme shepherding behavior

Novel Partitioned Time-Stepping Algorithms for Fast Computation of Random Interface-Coupled Problems with Uncertain Parameters

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NUMERICAL MATHEMATICS-THEORY METHODS AND APPLICATIONS 2024年第1期17卷 145-180页

作者： sun, Yizhong Wang, Jiangshan Zheng, Haibiao East China Normal Univ Sch Math Sci Shanghai Peoples R China East China Normal Univ Sch Math Sci Key Lab Math & Engn Applicat Shanghai Key Lab PMMPMinist Educ Shanghai Peoples R China

The simulation of multi-domain, multi-physics mathematical models with uncertain parameters can be quite demanding in terms of algorithm design and computation costs. Our main objective in this paper is to examine a physical interface coupling between two random dissipative systems with uncertain parameters. Due to the complexity and uncertainty inherent in such interface-coupled problems, uncertain diffusion coefficients or friction parameters often arise, leading to considering random systems. We employ Monte Carlo methods to produce independent and identically distributed deterministic heat-heat model samples to address random systems, and adroitly integrate the ensemble idea to facilitate the fast calculation of these samples. To achieve unconditional stability, we introduce the scalar auxiliary variable (SAV) method to overcome the time constraints of the ensemble implicit-explicit algorithm. Furthermore, for a more accurate and stable scheme, the ensemble data-passing algorithm is raised, which is unconditionally stable and convergent without any auxiliary variables. These algorithms employ the same coefficient matrix for multiple linear systems and enable easy parallelization, which can significantly reduce the computational cost. Finally, numerical experiments are conducted to support the theoretical results and showcase the unique features of the proposed algorithms.

关键词： Scalar auxiliary variable ensemble algorithm random interface-coupled problems implicit-explicit partitioned method data-passing partitioned method ENSEMBLE ALgORITHM ERROR ANALYSIS SAV SCHEMES FLOW STABILITY EFFICIENT MODEL

Control of 2-D Semi-Markov Jump Systems:A View from Mode generation Mechanism

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 258-260页

作者： Yunzhe Men Jian sun Jie Chen the National Key Laboratory of Autonomous Intelligent Unmanned Systems the School of AutomationBeijing Institute of TechnologyBeijing 100081 the Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China the Department of Control Science and Engineering Tongji UniversityShanghai 201804 the National Key Laboratory of Autonomous Intelligent Unmanned Systems Beijing Institute of TechnologyBeijing 100081China

Dear Editor,Two-dimensional(2-D) systems have wide applications in image data processing,gas absorption and fluid dynamics analysis [1]-[3].When there exist abrupt changes in 2-D systems,they are usually modeled by 2-D Markov jump systems(MJSs) or 2-D semi-Markov jump systems(SMJSs).This letter investigates the control of 2-D SMJSs based on a novel mode generation mechanism,which could avoid mode ambiguousness phenomenon caused by the evolution of system mode in two different *** criterion that guarantees the almost surely exponential stability of the system is obtained.A thermal process is studied to demonstrate the availability of the proposed method.

关键词： Markov mode system

Visualizing the crystallization of sodium chloride under supersaturated condition

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Nano Research 2024年第8期17卷 7786-7792页

作者： Mao Ye Tao xu Yuwei xiong Yatong Zhu Mingrui Zhou Longxiang Han Jinyi sun Ming Qin Litao sun SEU-FEI Nano-Pico Center Key Laboratory of MEMS of Ministry of EducationSchool of Integrated CircuitsSoutheast UniversityNanjing 210096China

Crystallization in supersaturated solution plays a fundamental role in a variety of natural and industrial ***,a thorough understanding of crystallization phenomena in supersaturated solution is still difficult because the real-time visualization of crystallization processes under supersaturated condition is a great ***,an electron beam-induced crystallization method was carried out in in situ liquid cell transmission electron microscopy(TEM)to visualize the crystallization of NaCl under supersaturated condition in real *** steps and behaviors in the crystallization of NaCl were captured and clarified,including the growth of NaCl nanocrystals with different morphologies,the formation of initial crystalline seeds from amorphous ion clusters,and the non-equilibrium growth behaviors caused by uneven distribution of precursor *** study provides the real-time visualization of detailed nucleation and growth behaviors in NaCl crystallization and brings an ideal strategy for investigating crystallization phenomena under supersaturated condition.

关键词： crystallization in situ liquid cell transmission electron microscopy(TEM) electron-water interaction sodium chloride

Editorial for the special issue“Hydrogen Energy Production,Storage and Utilization”

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Materials Reports(Energy) 2024年第1期4卷 1-2页

作者： Lixian sun guest Editor guilin University of Electronic Technology China

Hydrogen energy has emerged as a significant energy source for accomplishing energy transformation and achieving carbon *** production,storage and transportation are the key technologies to realize hydrogen energy application and carbon neutralization *** from the mature technologies of fossil fuel reforming and water electrolysis,new hydrogen production methods(such as solar photolysis,biomass conversion,thermochemical circulation,etc.)have garnered widespread attention and research *** lack of safe and efficient hydrogen storage and utilization technology for hydrogen fuel cell systems is the major obstacle to achieving hydrogen *** the past decades,global researchers have conducted extensive studies on enhancing the hydrogen storage performance of materials,such as alloy,metal hydride,complex hydride,carbon-based materials,etc.,as well as the technological development of fuel cell power generation systems using solid hydrogen storage materials as hydrogen storage *** themed issue entitled“Hydrogen Energy Production,Storage and Utilization”includes 10 carefully selected papers that address the most recent developments in hydrogen production and storage materials,involving catalyst design,structure characterization,hydrogen ab-/desorption performance and mechanism,and fuel cell coupling system exploit.

关键词： alloy Storage hydride

Predictor and ESO-based adaptive tracking control of heterogeneous vehicle platoon

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Science China(Technological Sciences) 2024年第9期67卷 2842-2852页

作者： sun ZhiZe LIU Yang ZHANg LinChuang College of Control Science and Engineering Bohai UniversityJinzhou 121013China College of Automation and Electronic Engineering Qingdao University of Science and TechnologyQingdao 266061China College of Information Science and Technology Bohai UniversityJinzhou 121013China

This paper investigates the distributed adaptive platoon tracking problem of third-order heterogeneous vehicles subject to model uncertainties. The design process is divided into two steps. Firstly, an adaptive tracking controller is designed for the dynamic leading vehicle. And then, the distributed adaptive controllers are established for followers. Moreover, the predictor technique is used to improve the estimate performance of the adaptive law, and the total disturbance is approximated and compensated by the variable gain nonlinear extended state observers(NESOs) driven by the estimation error. By introducing the variable gain hyperbolic tangent tracking differentiator(HTTD), the “complexity explosion” problem is avoided. The feasibility and effectiveness of the proposed protocol are verified by simulation tests.

关键词： variable gain NESOs heterogeneous vehicles platoon tracking predictor

Learning to sample initial solution for solving 0-1 discrete optimization problem by local search

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Science China Mathematics 2024年第6期67卷 1317-1340页

作者： xin Liu Jianyong sun Zongben xu School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an710049China

Local search methods are convenient alternatives for solving discrete optimization problems(DOPs).These easy-to-implement methods are able to find approximate optimal solutions within a tolerable time *** is known that the quality of the initial solution greatly affects the quality of the approximated solution found by a local search *** this paper,we propose to take the initial solution as a random variable and learn its preferable probability *** aim is to sample a good initial solution from the learned distribution so that the local search can find a high-quality *** develop two different deep network models to deal with DOPs established on set(the knapsack problem)and graph(the maximum clique problem),*** deep neural network learns the representation of an optimization problem instance and transforms the representation to its probability *** results show that given the initial solution sampled from the learned probability distribution,a local search method can acquire much better approximate solutions than the randomly-sampled initial solution on the synthesized knapsack instances and the Erd?s-Rényi random graph ***,with sampled initial solutions,a classical genetic algorithm can achieve better solutions than a random initialized population in solving the maximum clique problems on DIMACS ***,we emphasize that the developed models can generalize in dimensions and across graphs with various densities,which is an important advantage on generalizing deep-learning-based optimization algorithms.

关键词： discrete optimization deep learning graph convolutional network local search