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Nitrogen addition promotes soil carbon accumulation globally

Science China Life Sciences 2025年第1期68卷 284-293页

作者： Xuemei Yang Suhui Ma Erhan Huang Danhua Zhang guoping chen Jiangling Zhu chengjun Ji Biao Zhu Lingli Liu Jingyun Fang Institute of Ecology College of Urban and Environmental Sciencesand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking University Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China School of Ecology and Environmental ScienceYunnan University State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of Sciences

Soil is the largest carbon(C) reservoir in terrestrial ecosystems and plays a crucial role in regulating the global C cycle and climate *** nitrogen(N) deposition has been widely considered as a critical factor affecting soil organic carbon(SOC) storage, but its effect on SOC components with different stability remains unclear. Here, we analyzed extensive empirical data from 304 sites worldwide to investigate how SOC and its components respond to N addition. Our analysis showed that N addition led to a significant increase in bulk SOC(6.7%), with greater increases in croplands(10.6%) and forests(6.0%) compared to grasslands(2.1%). Regarding SOC components, N addition promoted the accumulation of plant-derived C(9.7%–28.5%) over microbial-derived C(0.2%), as well as labile(5.7%) over recalcitrant components(–1.2%), resulting in a shift towards increased accumulation of plant-derived labile C. Consistently, N addition led to a greater increase in particulate organic C(11.9%) than mineral-associated organic C(3.6%), suggesting that N addition promotes C accumulation across all pools, with more increase in unstable than stable pools. The responses of SOC and its components were best predicted by the N addition rate and net primary productivity. Overall, our findings suggest that N enrichment could promote the accumulation of plant-derived and non-mineral associated C and a subsequent decrease in the overall stability of soil C pool, which underscores the importance of considering the effects of N enrichment on SOC components for a better understanding of C dynamics in soils.

关键词： meta-analysis nitrogen enrichment soil organic carbon carbon accumulation carbon stability

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Stationary non-Gaussian random vibration control:A review

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Chinese Journal of Aeronautics 2021年第1期34卷 350-363页

作者： Ronghui ZHENG guoping chen Huaihai chen State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper presents a review of the various methods for the stationary non-Gaussian random vibration *** vibration tests can be divided,according to the number of exciters,in single-shaker tests and multiple-shaker *** the stationary non-Gaussian random vibration test,the time and frequency domain characteristics of the responses should be controlled independently and *** and kurtosis are usually selected as the nonGaussian time control references(targets)while power spectral density is the frequency domain control procedure before it recalls the concepts of ***,the generation of a one frame stationary non-Gaussian random signal for both the single and multiple shakers are *** commonly used methods for the single non-Gaussian random signal generation in the random vibration test are memoryless nonlinear transformation,phase modification and Filtered Poisson *** the multiple-shaker case,the sequential phase modification and memoryless nonlinear transformation are used to generate one frame coupled multi-channel non-Gaussian random *** order to obtain a stationary and consecutive dynamic input,the time domain randomization procedure is introduced with high computational efficiency and its influences on the skewness and kurtosis are ***,two existing problems in the non-Gaussian random vibration control are addressed.

关键词： non-Gaussian random Kurtosis Skewness Power spectral density Vibration control

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Static Frame Model Validation with Small Samples Solution Using Improved Kernel Density Estimation and Confidence Level Method

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Chinese Journal of Aeronautics 2012年第6期25卷 879-886页

作者： ZHANG Baoqiang chen guoping GUO Qintao State Key Laboratory of Mechanics and Control for Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China College of Mechanical and Electrical Engineering Nanjmg University of Aeronautics and Astronautics Nanjing 210016 China

An improved method using kernel density estimation （KDE） and confidence level is presented for model validation with small samples. Decision making is a challenging problem because of input uncertainty and only small samples can be used due to the high costs of experimental measurements. However, model validation provides more confidence for decision makers when improving prediction accuracy at the same time. The confidence level method is introduced and the optimum sample variance is determined using a new method in kernel density estimation to increase the credibility of model validation. As a numerical example, the static frame model validation challenge problem presented by Sandia National Laboratories has been chosen. The optimum bandwidth is selected in kernel density estimation in order to build the probability model based on the calibration data. The model assessment is achieved using validation and accreditation experimental data respectively based on the probability model. Finally, the target structure prediction is performed using validated model, which are consistent with the results obtained by other researchers. The results demonstrate that the method using the improved confidence level and kernel density estimation is an effective approach to solve the model validation problem with small samples.

关键词： model validation small samples uncertainty analysis kernel density estimation confidence level prediction

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Ligand density-dependent influence of arginine-glycine- aspartate functionalized gold nanoparticles on osteogenic and adipogenic differentiation of mesenchymal stem cells

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Nano Research 2018年第3期11卷 1247-1261页

作者： Jingchao Li Ying chen Naoki Kawazoe guoping chen Intemational Center for Materials Nanoarchitectonics National lnstitute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044Japan Department of Materials Science and Engineering Graduate School of Pure and Applied Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8577 Japan Research Center for Functional Materials National Institute for Materials Science 1- 1 Namiki Tsukuba Ibaraki 305-0044 Japan

Extracellular matrix （ECM） plays a very important role in regulating cell function and fate. It is highly desirable to fabricate biomimetic models to investigate the role of ECM in stem cell differentiation. In this study, arginine- glycine--aspartate （RGD）-modified gold nanoparticles （Au NPs） with tunable surface ligand density were prepared to mimic the ECM microenvironment. Their effect on osteogenic and adipogenic differentiation of human mesenchymal stem cells （MSCs） was investigated. The biomimetic Au NPs were taken up by MSCs in a ligand density-dependent manner. The biomimetic NPs with a high RGD density had an inhibitive effect on the alkaline phosphatase （ALP） activity, calcium deposition, and osteogenic marker gene expression of MSCs. Their effect on oil droplet formation and adipogenic marker gene expression was negative when RGD density was low, while their effect was promotive when RGD density was high. The biomimetic Au NPs regulated the osteogenic and adipogenic differentiation of MSCs mainly through affecting the focal adhesion and cytoskeleton. This study highlights the roles of biomimetic NPs on stem cell differentiation that could provide a meaningful strategy in fabricating functional biomaterials for tissue engineering and biomedical applications.

关键词： arginine-glycine--aspartate(RGD) density biomimetic goldnanopartides (Au NPs) osteogenic differentiation adipogenic differentiation mesenchymal stem cells

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Aeroelastic prediction and analysis for a transonic fan rotor with the“hot”blade shape

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Chinese Journal of Aeronautics 2021年第7期34卷 50-61页

作者： Di ZHOU Ziliang LU Tongqing GUO guoping chen Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper focuses on aeroelastic prediction and analysis for a transonic fan rotor with only its“hot”(running)blade shape available,which is often the case in practical engineering such as in the design *** on an in-house and well-validated CFD solver and a hybrid structural finite element modeling/modal approach,three main aspects are considered with special emphasis on dealing with the“hot”blade ***,static aeroelastic analysis is presented for shape transformation between“cold”(manufacturing)and“hot”blades,and influence of the dynamic variation of“hot”shape on evaluated aerodynamic performance is ***,implementation of the energy method for flutter prediction is given and both a regularly used fixed“hot”shape and a variable“hot”shape are *** comparison,influence of the dynamic variation of“hot”shape on evaluated aeroelastic stability is also ***,another common way to predict flutter,time-domain method,is used for the same concerned case,from which the predicted flutter characteristics are compared with those from the energy method.A well-publicized axial-flow transonic fan rotor,Rotor 67,is selected as a typical example,and the corresponding numerical results and discussions are presented in detail.

关键词： Energy method Fan rotor Flutter Running blade shape Static aeroelasticity Time-domain method

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ACTIVE CONTROL OF A FLEXIBLE CANTILEVER PLATE WITH MULTIPLE TIME DELAYS

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Acta Mechanica Solida Sinica 2008年第3期21卷 257-266页

作者： Longxiang chen Ji Pan guoping Cai Department of Engineering Mechanics Shanghai Jiaotong University Shanghai 200240 China

Active control of a flexible cantilever plate with multiple time delays is investigated using the discrete optimal control method. A controller with multiple time delays is presented. In this controller, time delay effect is incorporated in the mathematical model of the dynamic system throughout the control design and no approximations and assumptions are made in the controller derivation, so the system stability is easily guaranteed. Furthermore, this controller is available for both small time delays and large time delays. The feasibility and efficiency of the proposed controller are verified through numerical simulations in the end of this paper.

关键词： flexible cantilever plate multiple time delays discrete optima l control

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Modal and Fatigue Life Analysis on Beam with Multiple Cracks Subjected to Axial Force

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第5期35卷 874-882页

作者： Ma Yijiang chen guoping Wu Xinhai School of Naval Architecture and Ocean Engineering Jiangsu University of Science and Technology State Key Laboratory of Mechanics and Control for Mechanical Structures Nanjing University of Aeronautics and Astronautics

Based on the transfer matrix method and Forman equation,a new method is proposed to conduct the modal and fatigue life analysis of a beam with multiple transverse *** the modal analysis,the damping loss factor is introduced by the complex elastic modulus,bending springs without mass are used to replace the transverse cracks,and the characteristic transfer matrix of the whole cracked beam can be *** the fatigue life analysis,considering the interaction of the beam vibration and fatigue cracks growth,the fatigue life of the cracked beam is predicted by the timing analysis *** calculation shows that cracks have a significant influence on the modal and fatigue life of the beam.

关键词： beam cracks axial force natural frequency fatigue life

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Investigating long-term vehicle speed prediction based on GA-BP algorithms and the road-traffic environment

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Science China(Information Sciences) 2020年第9期63卷 121-123页

作者： Yufang LI chen REN Hongwei ZHAO guoping chen Department of Vehicle Engineering College of Energy & Power Engineering Nanjing University of Aeronautics and Astronautics Key Laboratory of Advanced Manufacture Technology for Automobile Parts (Chongqing University of Technology) Ministry of Education Foton Motor Group

Dear editor,Effective and accurate long-term speed prediction is crucial for intelligent transportation and automobile intelligent energy management systems of intelligent connected vehicles. These predictions have important research value and broad application prospects including widespread use in improving traffic efficiency and safety, fuel economy, remaining driving range estimation [1], and electric

关键词： long-term speed prediction road-traffic environment characteristic parameters description GA-BP network modeling

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A hierarchical updating method for finite element model of airbag buffer system under landing impact

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Chinese Journal of Aeronautics 2015年第6期28卷 1629-1639页

作者： He Huan chen Zhe He cheng Ni Lei chen guoping State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Institute of Vibration Engineering Research Nanjing University of Aeronautics and Astronautics Research Institute of Pilotless Aircraft Nanjing University of Aeronautics and Astronautics China Aviation Industry General Aircraft Co.Ltd.

In this paper, we propose an impact finite element （FE） model for an airbag landing buf- fer system. First, an impact FE model has been formulated for a typical airbag landing buffer system. We use the independence of the structure FE model from the full impact FE model to develop a hierarchical updating scheme for the recovery module FE model and the airbag system FE model. Second, we define impact responses at key points to compare the computational and experimental results to resolve the inconsistency between the experimental data sampling frequency and experi- mental triggering. To determine the typical characteristics of the impact dynamics response of the airbag landing buffer system, we present the impact response confidence factors （IRCFs） to evalu- ate how consistent the computational and experiment results are. An error function is defined between the experimental and computational results at key points of the impact response （KPIR） to serve as a modified objective function. A radial basis function （RBF） is introduced to construct updating variables for a surrogate model for updating the objective function, thereby converting the FE model updating problem to a soluble optimization problem. Finally, the developed method has been validated using an experimental and computational study on the impact dynamics of a classic airbag landing buffer system.

关键词： Airbag Hierarchical model Impact Model updating Radial basis function

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Model Updating for High Speed Aircraft in Thermal Environment Using Adaptive Weighted-Sum Methods

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第3期33卷 362-369页

作者： He Huan He cheng chen guoping The State Key Lab of Mechanics and Control for Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 P.R. China Research Institute of Pilotless Aircraft Nanjing University of Aeronautics and Astronautics Nanjing 210016 P.R. China

Model updating for aircraft in a high temperature environment(HTE)is proposed based on the hierarchical *** this method,the problem can be decomposed into temperature field updating and dynamic structural *** order to improve the estimation accuracy,the model updating problem is turned into a multi-objective optimization problem by constructing the objective function which combined with residues of modal frequency and effective modal *** the metamodeling,support vector regression(SVR)is introduced to improve the optimization efficiency,and the solution can be determined by adaptive weighted-sum method(AWS).Finally,the proposed method is tested on a finite element(FE)model of a reentry vehicle *** results show that the multi-objective model updating method in HTE can identify the input parameters of the temperature field and structure with good accuracy.

关键词： hierarchical high temperature environment(HTE) support vector regression(SVR) multi-objective optimization model updating

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