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Response of global agricultural productivity anomalies to drought stress in irrigated and rainfed agriculture

Science China Earth Sciences 2024年第11期67卷 3579-3593页

作者： Xinxin CHEN Lunche WANG Qian CAO Jia SUN Zigeng NIU Liu YANG Weixia JIANG Hubei key laboratory of Regional ecology and Environmental Change School of Geography and Information EngineeringChina University of Geosciences State key laboratory of Biogeology and Environmental Geology China University of Geosciences

The response of agricultural productivity anomalies to drought stress plays a crucial role in the carbon cycle within terrestrial ecosystems and in ensuring food security. However, detailed analysis of how global agricultural productivity anomalies response to drought stress, particularly within irrigated and rainfed agricultural systems, remains insufficient. In this study, the impact of drought stress on agricultural productivity anomalies during the growing season（zcNDVIS）, across both irrigated and rainfed agriculture, were analyzed using a suite of hydro-climatic variables. Specifically, the investigation utilized the multi-scalar Standardized Precipitation Evapotranspiration Index（SPEI）, the Multivariate ENSO Index（MEI）, and the Madden-Julian Oscillation（MJO）. Meanwhile, the relationships between hydroclimatic variables and zcNDVISwere analyzed at one, two, three and four months before the ending of growing season（EOS）. Results showed that（1） the percentages of significant（p<0.1） drying trends varied across the globe from 8.30% to 13.42%, 6.50% to 14.63%, 6.52% to 14.23%, and 6.47%to 14.95% at one-, two-, three-, and four-month lead times before EOS, respectively, during 2001–2020, which represented by the multiscalar SPEI. This observation highlights that most regions across the globe tend to be arid, which could significantly impact agricultural productivity;（2） the global mean correlation coefficients（rmax） for SPEI-1, SPEI-3, SPEI-6, SPEI-12（indicating SPEI at 1-, 3-, 6-, and 12-month lags）, MEI, and MJO with zcNDVISranged between 0.24–0.25, 0.27–0.28, 0.25–0.26, 0.21–0.22, –0.02–0.01 and 0.06–0.11, respectively, across both irrigated and rainfed agriculture system from 2001 to *** productivity anomalies demonstrated a significant correlation with drought stress. The strongest correlations were noted for SPEI-3 and SPEI-6, suggesting a delayed response of crops to drought conditions. This indicates that agriculture ecosystem experiences prolo

关键词： Drought Agricultural productivity anomaly Remote sensing MEI and MJO

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High-Efficiency Dynamic Scanning Strategy for Powder Bed Fusion by Controlling Temperature Field of the Heat-Affected Zone

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 203-214页

作者： Xiaokang Huang Xiaoyong Tian Qi Zhong Shunwen He Cunbao Huo Yi Cao Zhiqiang Tong Dichen Li State key laboratory of Manufacturing systems Engineering Xi’an Jiaotong UniversityXian 710049China

Improvement of fabrication efficiency and part performance was the main challenge for the large-scale powder bed fusion(PBF)*** this study,a dynamic monitoring and feedback system of powder bed temperature field using an infrared thermal imager has been established and integrated into a four-laser PBF equipment with a working area of 2000 mm×2000 *** heat-affected zone(HAZ)temperature field has been controlled by adjusting the scanning speed ***,the relationship among spot size,HAZ temperature,and part performance has been *** fluctuation of the HAZ temperature in four-laser scanning areas was decreased from 30.85℃to 17.41℃.Thus,the consistency of the sintering performance of the produced large component has been *** on the controllable temperature field,a dynamically adjusting strategy for laser spot size was proposed,by which the fabrication efficiency was improved up to 65.38%.The current research results were of great significance to the further industrial applications of large-scale PBF equipment.

关键词： Powder bed fusion Efficiency Large-scale Spot size Heat-affected zone(HAZ)

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Process in laser drilling of deep microholes without taper on metal materials

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Science China(Technological Sciences) 2024年第1期67卷 37-59页

作者： FAN RunZe MEI XueSong CUI JianLei State key laboratory for Manufacturing systems Engineering Xi’an Jiaotong UniversityXi’an 710054China

Deep microhole machining is currently a prominent research area within the aerospace field,encompassing blade film cooling and fuel injection control ***,taper defects in metal materials may lead to performance degradation or even structural damage over a component’s *** and helical drilling,facilitated by ultrashort pulse lasers,have proven more suitable for achieving high-precision,deep holes in metal ***,excessive repetition rates can also result in severe thermal *** methods are commonly employed for controlling taper,including parameter optimization,assistance,and secondary *** laser beam drilling is widely utilized and has been integrated into relevant machining systems for commercial *** deep microholes include film cooling holes and injection *** drilling is a potential machining method for new materials in the aerospace *** laser drilling processing has been studied,numerous related scientific challenges and technical difficulties must be addressed before practical implementation.

关键词： aerospace laser drilling deep microhole taper control

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Design of zero-determinant strategies and its application to networked repeated games

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Science China(Information Sciences) 2024年第10期67卷 227-243页

作者： Daizhan CHENG Changxi LI key laboratory of systems and Control Academy of Mathematics and Systems SciencesChinese Academy of Sciences School of Mathematics Shandong University

Using the semi-tensor product（STP） of matrices, the profile evolutionary equation（PEE） for repeated finite games is obtained. By PEE, the zero-determinant（ZD） strategies are developed for general finite games. A formula is then obtained to design ZD strategies for general finite games with multiple players and asymmetric strategies. A necessary and sufficient condition is obtained to ensure the availability of the designed ZD strategies. It follows that player i can unilaterally design ki-1（one less than the number of its strategies） dominating linear relations about the expected payoffs of all players. Finally, the fictitious opponent player is proposed for networked repeated games（NRGs）. A technique is proposed to simplify the model by reducing the number of frontier strategies.

关键词： finite repeated game profile evolutionary equation ZD strategy networked repeated games semi-tensor product of matrices

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Market Equilibrium Based on Cloud-edge Collaboration

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CSEE Journal of Power and Energy systems 2024年第1期10卷 96-104页

作者： Tong Cheng Haiwang Zhong Qing Xia the State key laboratory of Power systems the Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Market participants can only bid with lagged information disclosure under the existing market mechanism,which can lead to information asymmetry and irrational market behavior,thus influencing market *** promote rational bidding behavior of market participants and improve market efficiency,a novel electricity market mechanism based on cloudedge collaboration is proposed in this *** market information,called residual demand curve,is published to market participants in real-time on the cloud side,while participants on the edge side are allowed to adjust their bids according to the information disclosure prior to closure *** proposed mechanism can encourage rational bids in an incentive-compatible way through the process of dynamic equilibrium while protecting participants’*** paper further formulates the mathematical model of market equilibrium to simulate the process of each market participant’s strategic bidding behavior towards equilibrium.A case study based on the IEEE 30-bus system shows the proposed market mechanism can effectively guide bidding behavior of market participants,while condensing exchanged information and protecting privacy of participants.

关键词： Cloud-edge collaboration market mechanism residual demand curve strategic bidding

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Emergence of machine language: towards symbolic intelligence with neural networks

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National Science Review 2024年第4期11卷 27-30页

作者： Yuqi Wang Xu-Yao Zhang Cheng-Lin Liu Tieniu Tan Zhaoxiang Zhang State key laboratory of Multimodal Artificial Intelligence systems Institute of AutomationChinese Academy of Sciences

Representation learning is a core issue in artificial intelligence (AI). Currently,there exists a disparity in the choice of representation between humans and machines. Humans rely on discrete language for communicati...

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Design methodology,synthesis,and control strategy of the high-speed planetary rover

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Frontiers of Mechanical Engineering 2024年第2期19卷 59-74页

作者： Renchao LU Haibo GAO Zhen LIU Runze YUAN Zongquan DENG State key laboratory of Robotics and systems Harbin Institute of TechnologyHarbin 150001China

The planned missions to explore the surfaces of the Moon and Mars require high exploration efficiency,thus imposing new demands on the mobility system of planetary *** this paper,a design method for a high-speed planetary rover(HPR)is proposed,and the representative configurations are modeled and ***,the influence of the planetary surface environment on the design of HPRs is analyzed,and the design factors for HPRs are determined by studying a single-wheel ***,a design methodology for HPRs is *** adaptive suspension mechanisms of a four-wheeled rover are synthesized using the all-wheel-attachment condition and position and orientation characteristics theory,which are expressed in the form of a graph theory for the increase in elastic components and active ***,a dynamic model is built,and a simulation is carried out for the proposed *** validity of the proposed method and rover is verified,thus highlighting their potential application in future planetary exploration.

关键词： design methodology spectrum analysis high-speed planetary rover type synthesis

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Temperature is a cryptic factor shaping the geographical pattern of genetic variation in Ceratophyllum demersum across a subtropical freshwater lake

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Plant Diversity 2024年第5期46卷 630-639页

作者： Yixian Li Xuyao Zhao Manli Xia Xinzeng Wei Hongwei Hou The State key laboratory of Freshwater ecology and Biotechnology The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of SciencesInstitute of HydrobiologyChinese Academy of SciencesWuhan 430072HubeiChina University of Chinese Academy of Sciences Beijing 100049China key laboratory of Aquatic Botany and Watershed ecology Wuhan Botanical GardenChinese Academy of SciencesWuhan 430074HubeiChina

Macrophyte habitats exhibit remarkable heterogeneity,encompassing the spatial variation of abiotic and biotic components such as changes in water conditions and weather as well as anthropogenic *** factors are thought to be important drivers shaping the genetic and epigenetic variation of aquatic ***,the links among genetic diversity,epigenetic variation,and environmental variables remain largely unclear,especially for clonal aquatic ***,we performed population genetic and epigenetic analyses in conjunction with habitat discrimination to elucidate the environmental factors driving intraspecies genetic and epigenetic variation in hornwort(Ceratophyllum demersum)in a subtropical *** factors were highly correlated with the genetic and epigenetic variation of ***,with temperature being a key driver of the genetic *** temperature was detected to be correlated with greater genetic and epigenetic *** and epigenetic variation were positively driven by water temperature,but were negatively affected by ambient air *** findings indicate that the genetic and epigenetic variation of this clonal aquatic herb is not related to the geographic feature but is instead driven by environmental conditions,and demonstrate the effects of temperature on local genetic and epigenetic variation in aquatic systems.

关键词： Genetic diversity Epigenetic variation Temperature Macrophyte Restoration

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Ultrafast pulse-dilation framing camera and its application for time-resolved X-ray diagnostic

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Nuclear Science and Techniques 2024年第7期35卷 101-114页

作者： Hou-Zhi Cai Qiu-Yan Luo Kai-Xuan Lin Xuan Deng Jun-Kai Liu Kai-Zhi Yang Dong Wang Jia-Jie Chen Jia-Heng Wang Jing-Hua Long Li-Hong Niu Yun-Fei Lei Jin-Yuan Liu key laboratory of Optoelectronic Devices and systems of Ministry of Education and Guangdong Province Shenzhen Key Laboratory of Photonics and BiophotonicsCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen518060China

An ultrafast framing camera with a pulse-dilation device,a microchannel plate(MCP)imager,and an electronic imaging system were *** camera achieved a temporal resolution of 10 ps by using a pulse-dilation device and gated MCP imager,and a spatial resolution of 100μm by using an electronic imaging system comprising combined magnetic *** spatial resolution characteristics of the camera were studied both theoretically and *** results showed that the camera with combined magnetic lenses reduced the field curvature and acquired a larger working area.A working area with a diameter of 53 mm was created by applying four magnetic lenses to the ***,the camera was used to detect the X-rays produced by the laser-targeting *** diagnostic results indicated that the width of the X-ray pulse was approximately 18 ps.

关键词： Inertial confinement fusion Plasma diagnostics Framing camera Combined lenses Pulse-dilation

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Light weight design and integrated method for manufacturing hydraulic wheel-legged robots

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第9期25卷 701-715页

作者： Xu LI Haoyang YU Huaizhi ZONG Haibo FENG Yili FU State key laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China State key laboratory of Fluid Power and Mechatronic systems Zhejiang UniversityHangzhou 310058China

Design and manufacturing play pivotal roles in hydraulic-driven robotic ***,previous studies have emphasized mainly results and performance,often overlooking the specifics of the design and manufacturing *** paper introduces a novel approach known as light weight design and integrated manufacturing(LD&IM)for hydraulic wheel-legged *** LD&IM method leverages topology optimization and generative design techniques to achieve a substantial 45%weight reduction,enhancing the robot’s dynamic motion *** innovative design method not only streamlines the design process but also upholds the crucial attributes of light weight construction and high strength essential for hydraulic wheel-legged ***,the integrated manufacturing method,incorporating selective laser melting(SLM)and high-precision subtractive manufacturing(SM)processes,expedites the fabrication of high-quality *** the LD&IM approach,a hydraulic-driven single wheel-legged robot,denoted as WLR-IV,has been successfully *** robot boasts low mass and inertia,high strength,and a simplified component *** assess its dynamic jumping capabilities,the control loop integrates a linear quadratic regulator(LQR)and zero dynamic-based controller,while trajectory planning uses the spring-loaded inverted pendulum(SLIP)*** jumping results confirm the WLR-IV single-legged robot’s exceptional dynamic performance,validating both the effectiveness of the LD&IM method and the rationale behind the control strategy.

关键词： Wheel-legged robot Hydraulic driven Topology optimization Wheel-legged robot Hydraulic driven Topology optimization Additive manufacturing(AM) Jump control

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