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Temporal and spatial evolution of global major grain trade patterns

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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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A Transformer-Based Ensemble Framework for the Prediction of Protein-Protein Interaction Sites

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research 2024年第2期2023卷 703-718页

作者： Minjie Mou Ziqi Pan Zhimeng Zhou Lingyan Zheng Hanyu Zhang Shuiyang Shi Fengcheng Li Xiuna Sun Feng Zhu College of Pharmaceutical Sciences The Second Affliated HospitalZhejiang University School of MedicineNational Key Laboratory of Advanced Drug Delivery and Release SystemsZhejiang UniversityHangzhou 310058China Innovation institute for Artificial Intelligence in Medicine of Zhejiang University Alibaba-Zhejiang University Joint Research Center of Future Digital HealthcareHangzhou 330110China

The identification of protein-protein interaction (PPI) sites is essential in the research of protein function and the discovery of new drugs. So far, a variety of computational tools based on machine learning have been developed to accelerate the identification of PPI sites. However, existing methods suffer from the low predictive accuracy or the limited scope of application. Specifically, some methods learned only global or local sequential features, leading to low predictive accuracy, while others achieved improved performance by extracting residue interactions from structures but were limited in their application scope for the serious dependence on precise structure information. There is an urgent need to develop a method that integrates comprehensive information to realize proteome-wide accurate profiling of PPI sites. Herein, a novel ensemble framework for PPI sites prediction, EnsemPPIS, was therefore proposed based on transformer and gated convolutional networks. EnsemPPIS can effectively capture not only global and local patterns but also residue interactions. Specifically, EnsemPPIS was unique in (a) extracting residue interactions from protein sequences with transformer and (b) further integrating global and local sequential features with the ensemble learning strategy. Compared with various existing methods, EnsemPPIS exhibited either superior performance or broader applicability on multiple PPI sites prediction tasks. Moreover, pattern analysis based on the interpretability of EnsemPPIS demonstrated that EnsemPPIS was fully capable of learning residue interactions within the local structure of PPI sites using only sequence information. The web server of EnsemPPIS is freely available at http://***/ensemppis.

关键词： residue extracting ensemble

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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Coordinated Voltage Control of Distribution Network ConsideringMultiple Types of Electric Vehicles

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Energy Engineering 2024年第2期121卷 377-404页

作者： Liang Liu Guangda Xu Yuan Zhao Yi Lu Yu Li Jing Gao State Grid Jibei Electric Power research institute(North China Electric Power research institute Co. Ltd.)Beijing100045China

The couple between the power network and the transportation network(TN)is deepening gradually with the increasing penetration rate of electric vehicles(EV),which also poses a great challenge to the traditional voltage control *** this paper,we propose a coordinated voltage control strategy for the active distribution networks considering multiple types of *** the first stage,the action of on-load tap changer and capacitor banks,etc.,are determined by optimal power flow calculation,and the node electricity price is also determined based on dynamic time-of-use tariff *** the second stage,multiple operating scenarios of multiple types of EVs such as cabs,private cars and buses are considered,and the scheduling results of each EV are solved by building an optimization model based on constraints such as queuing theory,Floyd-Warshall algorithm and traffic flow *** the third stage,the output power of photovoltaic and energy storage systems is fine-tuned in the normal control *** charging power of EVs is also regulated in the emergency control mode to reduce the voltage deviation,and the amount of regulation is calculated based on the fair voltage control mode of ***,we test the modified IEEE 33-bus distribution system coupled with the 24-bus Beijing *** simulation results show that the proposed scheme can mitigate voltage violations well.

关键词： Electric vehicle transportation network voltage control queuing theory

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)

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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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

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

Comparative analysis between single-train passing and double-train intersection in a tunnel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第5期25卷 429-442页

作者： Jianming DU Qian FANG Xuan ZHANG Hualao WANG Bridge and Tunnel research Center Research Institute of Highway Ministry of TransportBeijing 100088China Tunnel and Underground Engineering research Center of Ministry of Education Beijing Jiaotong UniversityBeijing 00044China

Aerodynamic pressure significantly impacts the scientific evaluation of tunnel service *** aerodynamic pressure of two trains running in a double-track tunnel is considerably more complicated than that of a single *** used the numerical method to investigate the difference in aerodynamic pressure between a single train and two trains running in a double-track ***,the numerical method was verified by comparing the results of numerical simulation and on-site ***,the characteristics of aerodynamic pressure were ***,the influence of various train-tunnel factors on the characteristics of aerodynamic pressure was *** results show that the aerodynamic pressure variation can be divided into stage I:irregular pressure fluctuations before the train tail leaves the tunnel exit,and stage II:periodic pressure declines after the train tail leaves the tunnel *** addition,the aerodynamic pressure simultaneously jumps positively or drops negatively for a single train or two trains running in double-track tunnel *** pressure amplitude in the two-train case is higher than that for a single *** maximum positive peak pressure difference(P_(STP))and maximum negative peak pressure difference(P_(STN))increase as train speed rises to the power from 2.256 to 2.930 in stage *** P_(STP) and P_(STN) first increase and then decrease with the increase of tunnel length in stage *** P_(STP) and P_(STN) increase as the blockage ratio rises to the power from 2.032 to 2.798 in stages I and II.

关键词： Railway tunnel Aerodynamic effect Pressure characteristic Train speed Tunnel length Blockage ratio