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Greenhouse gas budget for terrestrial ecosystems in China

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Science China Earth Sciences 2012年第2期55卷 173-182页

作者： cai ZuCong State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

Terrestrial ecosystems may act as a source or a sink for the atmospheric greenhouse gases, carbon dioxide (CO2), methane (CH4), and nitrous oxide (n2O), depending on land use and management. This paper reviews the literature on carbon, CH4, and n2O fluxes from terrestrial ecosystems in China, and analyzes its national greenhouse gas budget. Carbon storage in biomass and soils in Chinese terrestrial ecosystems decreased in the past 300 years, due to deforestation and expansion of cultivated land, and reached a minimum in the late 1970s. Since then, carbon storage has increased at an estimated rate of 0.19 to 0.26 Pg C yr-1, mainly owing to reforestation and afforestation. CH4 emission from natural wetlands decreased from 6.65 Tg CH4 yr-1 in 1990 to 5.71 Tg CH4 yr-1 in 2000 owing to the decrease in wetland area. CH4 emission from flooded rice fields was 7.41 Tg CH4 yr-1. At the same time, aerobic soils took up atmospheric CH4 at a rate of 2.56 Tg CH4 yr-1. nitrous oxide emission from forestlands, grasslands, and farmlands was positively correlated with precipitation at a national scale, and the emission rate was positively correlated with the CH4 uptake rate of forestlands and grasslands (Pnatural n2O sources were estimated to be 419 Gg n yr-1 and anthropogenic sources (from farmlands) to be 292 to 476.3 Gg n yr-1, with a mean of 372.6 Gg n yr-1. The integrated budget of greenhouse gasses indicates that Chinese terrestrial ecosystems act as a small net sink for global warming potential (GWP), ranging from 0.04 to 0.32 Pg CO2-eq yr-1, in a striking contrast to terrestrial ecosystems globally, which are a source of 2.75 to 6.78 Pg CO2-eq yr-1. The ratios of anthropogenic to natural sources of CH4 and n2O are much larger in Chinese terrestrial ecosystems than they are in global averages, reflecting greater human disturbance of terrestrial ecosystems in China.

关键词： terrestrial ecosystems carbon dioxide methane nitrous oxide

Percolation of Mobile Individuals on Weighted Scale-Free networks

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Chinese Physics Letters 2011年第11期28卷 278-281页

作者： WU An-cai Department of Physics Harbin Institute of TechnologyHarbin 150006

The percolation-like phase transition of mobile individuals is studied on weighted scale-free(WSF)networks,in which the maximum occupancy at each node is one individual(*** core interaction)and individuals can move to neighbor void ***,the condition for the existence of a spanning cluster of individuals(a connected cluster of neighbor nodes occupied by individuals that span the entire systems)is investigated and it is found that there exists a critical value of weight coupling parameter𝛽βc,above which the density threshold of individuals is zero and below which the density threshold is larger than zero for WSF networks in the thermodynamic limit n→∞.Furthermore,the finite size scaling analysis show that for certain value𝛽β,the percolation transition of mobile individuals on a WSF network belongs to the same universality class of regular random graph percolation.

关键词： percolation cluster neighbor

Density Functional Theory Study on Interaction between Catechin and Thymine

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Chinese Journal of Chemical Physics 2012年第6期25卷 642-648,I0003页

作者： Wan-fei cai Yan Zheng Lai-cai Li An-min Tian Departement of Chemistry and Material Science Sichuan Normal University Chengdu 510065China Departement of Chemistry Sichuan University Chengdu 510054 China

The interacting patterns and mechanism of the catechin and thymine have been investigated with the density functional theory Becke＇s three-parameter nonlocal exchange functional and the Lee, Yang, and Parr nonlocal correlation functional （B3LYP） method by 6-31＋G＊ basis set. Thirteen stable structures for the catechin-thymine complexes have been found which form two hydrogen bonds at least. The vibrational frequencies are also studied at the same level to analyze these complexes. The results indicated that catechin interacted with thynfine by three different hydrogen bonds as n-H…O, C-H…O, O-H…O and the complexes are mainly stabilized by the hydrogen bonding interactions. Theories of atoms in molecules and natural bond orbital have been adopted to investigate the hydrogen bonds involved in all systems. The interaction energies of all complexes have been corrected for basis set superposition error, which are from -18.15 k J/mol to -32.99 kJ/mol. The results showed that the hydrogen bonding contribute to the interaction energies dominantly. The corresponding bonds stretching motions in all complexes are red-shifted relative to that of the inonomer, which is in agreement with experimental results.

关键词： Density functional theory Thymine Hydrogen bond Catechin

Wave function collapses and 1/n energy spectrum induced by a Coulomb potential in a one-dimensional flat band system

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Chinese Physics B 2022年第5期31卷 173-179页

作者： Yi-cai Zhang School of Physics and Materials Science Guangzhou UniversityGuangzhou 510006China

We investigate the bound state problem in a one-dimensional flat band system with a Coulomb *** is found that,in the presence of a Coulomb potential of type I(with three equal diagonal elements),similarly to that in the twodimensional case,the flat band could not *** the same time,the flat band states are transformed into localized states with a logarithmic singularity near the center *** addition,the wave function near the origin would collapse for an arbitrarily weak Coulomb *** to the wave function collapses,the eigen-energies for a shifted Coulomb potential depend sensitively on the cut-off *** a Coulomb potential of type II,there exist infinite bound states that are generated from the flat ***,when the bound state energy is very near the flat band,the energy is inversely proportional to the natural number,e.g.,E_(n)∝1/n,n=1,2,3,...It is expected that the 1/n energy spectrum could be observed experimentally in the near future.

关键词： wave function collapses flat band infinite bound states

A multi-objective multi-memetic algorithm for network-wide conflict-free 4D flight trajectories planning

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Chinese Journal of Aeronautics 2017年第3期30卷 1161-1173页

作者： Su YAn Kaiquan cai School of Electronics and Information Engineering Beihang University Beijing 100191 China Beijing Key Laboratory of network Enabled Collaborative ATM Beijing 100191 China

Under the demand of strategic air traffic flow management and the concept of trajectory based operations（TBO）,the network-wide 4D flight trajectories planning（n4DFTP） problem has been investigated with the purpose of safely and efficiently allocating 4D trajectories（4DTs）（3D position and time） for all the flights in the whole airway *** that the introduction of large-scale 4DTs inevitably increases the problem complexity,an efficient model for strategiclevel conflict management is developed in this ***,a bi-objective n4 DFTP problem that aims to minimize both potential conflicts and the trajectory cost is *** consideration of the large-scale,high-complexity,and multi-objective characteristics of the n4DFTP problem,a multi-objective multi-memetic algorithm（MOMMA） that incorporates an evolutionary global search framework together with three problem-specific local search operators is *** is capable of rapidly and effectively allocating 4DTs via rerouting,target time controlling,and flight level ***,to balance the ability of exploitation and exploration of the algorithm,a special hybridization scheme is adopted for the integration of local and global *** studies using real air traffic data in China with different network complexities show that the proposed MOMMA is effective to solve the n4 DFTP *** solutions achieved are competitive for elaborate decision support under a TBO environment.

关键词： Air traffic flow management 4D trajectory planning Multi-memetic algorithm Multi-objective optimization network-wide strategic conflict management

Leader-following adaptive consensus of multiple uncertain rigid spacecraft systems

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Science China(Information Sciences) 2016年第1期59卷 6-18页

作者： He cai Jie HUAnG Shenzhen Research Institute The Chinese University of Hong Kong Department of Mechanical and Automation Engineering The Chinese University of Hong KongShatin N.T.

The existing results on the leader-following attitude consensus for multiple rigid spacecraft systems assume that all the parameters of the spacecraft systems are known exactly and the information flow among the followers is bidirectional. In this paper, we remove these two assumptions. First, by introducing a new Lyapunov function, we allow the communication network to be directed. Second, we convert the leader-following consensus problem into an adaptive stabilization problem of a well defined error system. Then, under the standard assumption that the state of the leader system can reach every follower through a directed path, we further show that this stabilization problem is solvable by a distributed adaptive control law. Moreover, we also present the sufficient condition for guaranteeing the convergence of the estimated parameters to the unknown actual parameters.

关键词： adaptive control attitude consensus multi-agent system nonlinear distributed observer parameter convergence

Effect of titanium content on the refinement of coarse columnar austenite grains during the solidification of peritectic steel

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International Journal of Minerals,Metallurgy and Materials 2022年第12期29卷 2172-2180页

作者： Jiazhi An Zhaozhen cai Miaoyong Zhu Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China

The effect of titanium content on the refinement of austenite grain size in as-cast peritectic carbon steel was investigated by fast directional solidification experiments with simulating the solidification and growth of surface and subsurface austenite in continuously cast *** electron microscope(TEM)and scanning electron microscope(SEM)were used to analyze the size and distribution of Ti(C,n)precipitates during *** on these results,the pinning pressure of Ti(C,n)precipitates on the growth of coarse columnar grains(CCGs)was *** results show that the austenite microstructure of as-cast peritectic carbon steel is mainly composed of the regions of CCGs and fine columnar grains(FCGs).Increasing the content of titanium reduces the region and the short axis of the *** the content of titanium is 0.09wt%,there is no CCG *** microscale particles will firstly form in the liquid,which will decrease the transition temperature from FCGs to *** chain-like nanoscale Ti(C,n)will precipitate with the decrease of the transition ***,calculations shows that the refinement of the CCGs is caused by the pinning effect of Ti(C,n)precipitates.

关键词： peritectic steel grain refinement coarse columnar grain titanium carbonitride pinning pressure

An ultra-porous g-C_(3)n_(4) micro-tube coupled with MXene(Ti_(3)C_(2)TX)nanosheets for efficient degradation of organics under natural sunlight

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Journal of Environmental Sciences 2024年第3期137卷 258-270页

作者： Zongyang Ya Qiyou Wang Jingjin cai Peng Wang Xinyu Jiang zhiy.n cai Shanglin Xiang Tingwei Wang Dongyu cai College of Materials Science&Engineering Nanjing Tech University30 South PuZhu RoadNanjing 211816China Key Laboratory of Flexible Electronics(KLOFE)&Institute of Advanced Materials(IAM) Jiangsu National Synergetic Innovation Center for Advanced Materials(SICAM)Nanjing Tech University30 South PuZhu RoadNanjing 211816China

It remains as a challenge for realizing efficient photo-responsive catalysts towards largescale degradation of organic pollutants under natural *** work reports a new pore engineering strategy for creating ultra-porous g-C_(3)n_(4) micro-tubes with an unprecedentedly high specific surface area of 152.96 m^(2)/*** is mainly associated with releasing internal vapor pressure in the autoclave where the hydrothermal treatment of the urea/melamine mixture is *** by microscopic observation,porosity measurement and spectroscopic characterization,it is found that releasing the pressure at halfway of hydrothermal process is vital for forming exfoliated rod-like precursors and the de-aggregation of these rods presents substantial benefits on the production of mesopores on g-C_(3)n_(4) microtubes during the calcination of *** offers a large number of reactive sites required by photocatalytic *** these micro-tubes with Ti_(3)C_(2)T_(X) nanosheets via electrostatic interaction yields a 1D/2D heterojunction with a close interfacial *** addition of metallically conductive Ti_(3)C_(2)T_(X) nanosheets accelerates the separation between electrons and holes,and also enhances the light *** these merits of structural design lead to forming a group of highly efficient catalysts demonstrating an excellent photocatalytic degradation rate of k=0.0560 min^(-1)for RhB dyes under 100 mW/cm~2 visible light radiation that micks sunlight *** laboratory valuation is further supported by an outdoor test that shows a fast degradation rate of 0.0744 min^(-1)under natural sunlight.

关键词： Carbon nitride MXene Heterojunction Photocatalysis

Twistors for modules over algebras

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Science China Mathematics 2016年第7期59卷 1327-1344页

作者： SUn Jian cai Department of Mathematics Shanghai University

We study the concept of module twistor for a module over an algebra. This concept provides a unifying framework for various deformed constructions of modules over algebras, such as module R-matrices,(n-factor iterated) twisted tensor products and L-R-twisted tensor products of algebras. Among the main results,we find the relations among these constructions. Furthermore, we study some properties of module twistors.

关键词： twistor module algebra