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Temporal and spatial evolution of global major grain trade patterns

Journal of Integrative Agriculture 2024年第3期23卷 1075-1086页

作者： Ziqi Yin Jiaxuan Hu Jing Zhang Xiangyang Zhou Lingling Li Jianzhai Wu Agricultural Information institute Chinese Academy of Agricultural SciencesBeijing 100081China institute of Scientific and Technical Information of China Beijing 100038China Zibo Agricultural Science research institute Zibo 255000China Zibo institute for Digital Agriculture and Rural research Zibo 255000China

The complex and volatile international landscape has significantly impacted global grain supply security. This study uses a complex network analysis model to examine the evolution and trends of the global major grain trade from 1990 to 2020, focusing on network topology, centrality ranking, and community structure. There are three major findings. First, the global major grain trade network has expanded in scale, with a growing emphasis on diversification and balance. During the study period, the United States, Canada, China, and Brazil were the core nodes of the network. Grain-exporting countries were mainly situated in Asia, the Americas, and Europe, and importing countries in Asia, Africa, and Europe. Second, a significant increase in the number of high centrality countries with high export capacity occurred, benefiting from natural advantages such as fertile land and favorable climates. Third, the main global grain trade network is divided into four communities, with the Americas-Europe community being the largest and most widespread. The formation of the community pattern was influenced by geographic proximity, driven by the core exporting countries. Therefore, the world needs to enhance the existing trade model, promote the multi-polarization of the grain trade network, and establish a global vision for the future community. Countries and regions should participate actively in global grain trade security governance and institutional reform, expand trade links with other countries, and optimize import and export policies to reduce trade risks.

关键词： grain trade pattern evolution complex network

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Optimized scheduling of integrated energy systems for low carbon economy considering carbon transaction costs

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Global Energy Interconnection 2024年第4期7卷 377-390页

作者： Chao Liu Weiru Wang Jing Li Xinyuan Liu Yongning Chi China Electric Power research institute Beijing 100192P.R.China State Grid Shanxi Electric Power research institute Taiyuan 030001P.R.China

With the introduction of the“dual carbon”goal and the continuous promotion of low-carbon development,the integrated energy system(IES)has gradually become an effective way to save energy and reduce *** study proposes a low-carbon economic optimization scheduling model for an IES that considers carbon trading *** the goal of minimizing the total operating cost of the IES and considering the transferable and curtailable characteristics of the electric and thermal flexible loads,an optimal scheduling model of the IES that considers the cost of carbon trading and flexible loads on the user side was *** role of flexible loads in improving the economy of an energy system was investigated using examples,and the rationality and effectiveness of the study were verified through a comparative analysis of different *** results showed that the total cost of the system in different scenarios was reduced by 18.04%,9.1%,3.35%,and 7.03%,respectively,whereas the total carbon emissions of the system were reduced by 65.28%,20.63%,3.85%,and 18.03%,respectively,when the carbon trading cost and demand-side flexible electric and thermal load responses were considered *** electrical and thermal loads did not have the same impact on the system *** the analyzed case,the total cost and carbon emissions of the system when only the flexible electrical load response was considered were lower than those when only the flexible thermal load response was taken into *** have an excess of carbon trading credits and can profit from selling them,whereas other devices have an excess of carbon trading and need to buy carbon credits.

关键词： Demand response Combined cooling Heating and power system Carbon transaction costs Flexible electric and thermal loads Optimal scheduling

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Chromosome-level genome assembly of the Asian citrus psyllid,Diaphorina citri

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Insect Science 2024年第1期31卷 13-27页

作者： Shuang Lei Shi-Jiang Yu Qi Pan Li-Li Ding Si-Chen Li Lu-Yan Cheng Shu-Qi Wang Bing-Hai Lou Jun He Cui-Yun Lei Lin Cong Hao-Qiang Liu Xue-Feng Wang Chun Ran Citrus research institute Southwest University/Chinese Academy of Agricultural SciencesNational Engineering Research Center for CitrusChongqingChina

Diaphorina citri is a global citrus *** a vector insect,it can transmit the causative agents of citrus huanglongbing,causing irreversible losses to the citrus *** acquisition of genomic information can provide a molecular genetic basis for effective control of ***,the DNBSEQ™,Oxford Nanopore Technologies,and Hi-C technologies are applied to generate a high-quality chromosome-level genome of *** genome size of *** was 523.78 Mb with a scaffold N50 of 47.05 Mb distributed on 13 chromosomes.A total of 250.64 Mb(47.85%)repeat sequences and 24048 protein-coding genes were *** resequencing of female and male individuals indicated that the sex chromosome system of *** is *** analysis demonstrated that *** and Pachypsylla venusta,which separated from their most recent common ancestor about 336.62 million years ago,were the most closely ***,we identified genes potentially involved in detoxification metabolism,pathogen transmission,and honeydew secretion for further *** high-quality genome provides an important reference for developing effective management strategies of ***.

关键词： Asian citrus psyllid chromosome-level genome comparative genomics cytochrome P450 detoxification Huanglongbing

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Transient Stability Analysis and Design of VSGs with Different DC-Link Voltage Controllers

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 593-604页

作者： Chao Shen Wei Gu Wanxing Sheng Keyan Liu School of Electrical Engineering Southeast UniversityNanjingChina Power Distribution research Department China Electric Power Research InstituteBeijing 100192China

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

关键词： DC-link voltage dynamics equal area criterion(eac) transient synchronization stability virtual synchronous generator(VSG)

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Optimizing temperature coefficient of Sm2Co17-type magnets through adjusting the isothermal aging process

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Journal of Rare Earths 2024年第11期42卷 2097-2104页

作者： Chao Wang Die Hu Qiangfeng Li Yikun Fang Meng Zheng Lei Wang Hongsheng Chen Lei Zhao Haizhou Wang Minggang Zhu Wei Li Division of Functional Materials research Central Iron and Steel Research Institute Shanghai Aerospace Control Technology institute Beijing Advanced Innovation Center for Materials Genome Engineering Central Iron and Steel Research Institute Beijing Key Laboratory of Metal Materials Characterization Central Iron and Steel Research Institute

The high-temperature magnetic perfo rmance and micro structure of Sm1-xGdx(CobalFe0.09Cu0.09Zr0.025)7.2（x=0.3,0.5） magnets were *** the isothermal aging time decreasing from 11 to 3 h,the temperature coefficient of intrinsic coercivity in the temperature range of 25-500℃,β25-500℃,was optimized from -0,167%/℃ to-0.112%/℃ for x=0.3 *** noticeable enhancement（～33%） of temperature stability is correlated with the increased content of 1:5H cell boundary phase and its relatively high Curie temperature as ***,for the x=0.5 magnet,it is found that the presence of Sm5Co19phases and wider nanotwin variants hinder the formation of 1:5H cell boundary *** insufficient 1:5H is not beneficial to the proper redistribution of Cu in cell boundary,making the x=0.5 magnet difficult to achieve higher temperature ***,the approach of adjusting the isothermal aging process can offer guidance for attaining superior magnetic performance in the temperature range from 25 to 500℃ for Gd-substituted Sm2Co17-type magnets.

关键词： Isothermal aging process Rare earths Sm2Co17-type magnets Temperature coefficient of intrinsic coercivity

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Low-Temperature Reforming Products Coupling Spark Plug on Gasoline Compression Ignition and Combustion Characteristics under Low-Load Condition

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Journal of Thermal Science 2024年第06期33卷 2386-2398页

作者： LIU Long LI Mingkun CAO Qun WANG Yang WANG Xichang College of Power and Energy Engineering Harbin Engineering University China Helicopter research and Development institute

Gasoline compression combustion engine has the advantages of low emission and high efficiency,which is very promising for research,but it is difficult to apply under low-load *** has the characteristics of low reactivity;in the case of low thermodynamic state in the cylinder,the fire delay period of the fuel is longer,and the combustion phase is relatively lagging,which will lead to the increase of combustion cycle fluctuations,and even difficult to ignite and other adverse combustion *** order to improve the combustion stability of Gasoline Compression Ignition（GCI） engine under low-load condition and expand the limit of low-load combustion boundary,gasoline was reformed without catalyst under the boundary condition of reforming temperature of 488 K and reforming equivalent ratio of 8,and the concentration of reformed product was measured by a gas detection ***,the coupling of the reformed product and spark plug with GCI engine under low-load condition was investigated to analyze the effect on engine combustion and *** results showed that the initial combustion timing of the low-load GCI engine was late,but the addition of reformed products could advance the combustion phase,shorten the combustion duration,reduce single-cycle NOxemission,and improve the small-load operation characteristics of GCI *** spark plug ignition on the basis of adding reformed products could further improve the problem of combustion stability under low-load GCI *** the optimization effect became more obvious as the ignition position of the spark plug moves ***,spark plug ignition would cause local high temperature areas,resulting in an increase in NOxemission.

关键词： combustion emission gasoline low-temperature reform spark plug

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A survey of decision making in adversarial games

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Science China(Information Sciences) 2024年第4期67卷 85-112页

作者： Xiuxian LI Min MENG Yiguang HONG Jie CHEN College of Electronics and Information Engineering Tongji University Shanghai research institute for Intelligent Autonomous Systems

In many practical applications, such as poker, chess, drug interdiction, cybersecurity, and national defense, players often have adversarial stances, i.e., the selfish actions of each player inevitably or intentionally inflict loss or wreak havoc on other players. Therefore, adversarial games are important in realworld applications. However, only special adversarial games, such as Bayesian games, are reviewed in the literature. In this respect, this study aims to provide a systematic survey of three main game models widely employed in adversarial games, i.e., zero-sum normal-form and extensive-form games, Stackelberg(security) games, and zero-sum differential games, from an array of perspectives, including basic knowledge of game models,(approximate) equilibrium concepts, problem classifications, research frontiers,(approximate) optimal strategy-seeking techniques, prevailing algorithms, and practical applications. Finally, promising future research directions are also discussed for relevant adversarial games.

关键词： adversarial games zero-sum games Stackelberg games differential games Nash equilibrium correlated equilibrium regret

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Fracture behavior and mechanism of highly fragmented steel cylindrical shell under explosive loading

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Defence Technology（防务技术） 2024年第6期36卷 122-132页

作者： Kang Wang Peng Chen Xingyun Sun Yufeng Liu Jiayu Meng Xiaoyuan Li Xiongwei Zheng Chuan Xiao Xi'an Modern Chemistry research institute Xi'an 710065China Shanxi Jiangyang Chemical Company Limited Taiyuan 030051China Central Iron&Steel research institute Company Limited Beijing 100081China China research and Development Academy of Machinery Equipment Beijing 100089China

An in-depth understanding of the fracture behavior and mechanism of metallic shells under internal explosive loading can help develop material designs for warheads and regulate the quantity and mass distribution of the fragments *** study investigated the fragmentation performance of a new high-carbon silicon-manganese(HCSiMn)steel cylindrical shell through fragment recovery *** with the conventional 45Cr steel shell,the number of small mass fragments produced by the HCSi Mn steel shell was significantly increased with a scale parameter of 0.57 g fitted by the Weibull distribution *** fragmentation process of the HCSi Mn shell exhibited more brittle tensile fracture characteristics,with the microcrack damage zone on the outer surface being the direct cause of its high *** the one hand,the doping of alloy elements resulted in grain refinement by forming metallographic structure of tempered sorbite,so that microscopic intergranular fracture reduces the characteristic mass of the fragments;on the other hand,the distribution of alloy carbides can exert a"pinning"effect on the substrate grains,causing more initial cracks to form and propagate along the brittle carbides,further improving the shell *** the killing power radius for light armored vehicles was slightly reduced by about 6%,the dense killing radius of HCSiMn steel projectile against personnel can be significantly increased by about 26%based on theoretical *** results provided an experimental basis for high fragmentation warhead design,and to some extent,revealed the correlation mechanism between metallographic structure and shell fragmentation.

关键词： Projectile fragmentation Fragment mass distribution Fracture mode Metallographic structure Damage power

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Preparation and characterization of Rb-doped TiO_(2) powders for photocatalytic applications

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Rare Metals 2024年第2期43卷 555-561页

作者： Lu Jia Li-Mei Yang Wei Wang Song-Tao Huang Zheng Xu National Engineering Laboratory of Biohydrometallurgy General Research Institute for Nonferrous MetalsBeijing100088China

TiO_(2)nanoparticles doped with different concentrations of Rb were prepared by sol–gel *** crystal structures of samples were characterized by X-ray diffraction(XRD)and transmission electron microscopy(TEM).It was confirmed by the Rietveld refinement method that the as-prepared samples crystallize in anatase phase and Rb doping induces expansion and distortion of the crystal *** with the pure TiO_(2),the Rb-doped nanoparticles have smaller crystal size and better *** rate of methylene blue was used to evaluate the photocatalytic activity of Rb–TiO_(2).It indicated that doping Rb into TiO_(2)can effectively improve the photocatalytic activity of TiO_(2)and the mechanisms were discussed in *** using the sample doped with 0.20%Rb,methylene blue degraded with the fastest rate(97%within 60 min).

关键词： Rb doping TiO_(2) Photocatalysis Sol-gel

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Architecture and exploration target areas of the Senegal Basin,West Africa

Energy Geoscience

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Energy Geoscience 2024年第4期5卷 174-186页

作者： Naxin Tian Gaokui Wu Min Gao Yue Gong Dapeng Wang Zhipeng Liu SINOPEC Exploration and Production research institute Beijing102206China

The recent discovery of large oil and gas fields in the deep-water of the Senegal Basin has drawn global *** this,several exploration wells in this area fail,which can be primarily contributed to a lack of understanding of the basin's structures and hydrocarbon accumulation *** study examines these characteristics utilizing gravity,seismic and drilling data,and finally makes a comparison with the Cote d’Ivoire Basin,a typical transform margin basin in the South *** results suggest that the Senegal Basin,influenced by multiple transform faults and a weak Paleozoic basement,experienced three evolutionary stages:rifting,transitional,and *** stage contributed to the development of distinct depositional sequences-syn-rift sequences,sag sequences,and continental margin sequences,*** Triassic-Early Jurassic rifting stage predominantly formed continental deposits,like fluvial,lacustrine,and deltaic deposits,in the syn-rift *** Middle-Late Jurassic transitional stage,influenced by transform faults,witnessed the formation of marginal ridges or submarine uplift *** zones,in conjunction with landward high terrains,formed a restricted environment promoting the development of source rocks in the sag *** the drifting stage,three types of reservoirs,namely platform carbonate rocks,deltas,and slope-floor fans were ***,large-scale hydrocarbon reservoirs have been found in the deltas and the slope-floor fans both in the Senegal Basin and the Cote d’Ivoire *** Upper Jurassic-Aptian platforms exhibit thick carbonate rocks and organic reefs on their edges,suggesting substantial potential for hydrocarbon exploration in the Senegal Basin.

关键词： Transform-extensional passive continental margin Basin architecture Accumulation model Senegal Basin West Africa

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