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Ionospheric vertical total electron content prediction model in low-latitude regions based on long short-term memory neural network

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Chinese Physics B 2022年第8期31卷 347-358页

作者： tong-bao zhang Hui-Jian Liang Shi-Guang Wang Chen-Guang Ouyang Department of Precision Instrument Tsinghua UniversityBeijing 100084China State Key Laboratory of Precision Measurement Technology and Instrument Tsinghua UniversityBeijing 100084China Department of Electronic Engineer Tsinghua UniversityBeijing 100084China

Ionosphere delay is one of the main sources of noise affecting global navigation satellite systems, operation of radio detection and ranging systems and very-long-baseline-interferometry. One of the most important and common methods to reduce this phase delay is to establish accurate nowcasting and forecasting ionospheric total electron content models. For forecasting models, compared to mid-to-high latitudes, at low latitudes, an active ionosphere leads to extreme differences between long-term prediction models and the actual state of the ionosphere. To solve the problem of low accuracy for long-term prediction models at low latitudes, this article provides a low-latitude, long-term ionospheric prediction model based on a multi-input-multi-output, long-short-term memory neural network. To verify the feasibility of the model, we first made predictions of the vertical total electron content data 24 and 48 hours in advance for each day of July 2020 and then compared both the predictions corresponding to a given day, for all days. Furthermore, in the model modification part, we selected historical data from June 2020 for the validation set, determined a large offset from the results that were predicted to be active, and used the ratio of the mean absolute error of the detected results to that of the predicted results as a correction coefficient to modify our multi-input-multi-output long short-term memory model. The average root mean square error of the 24-hour-advance predictions of our modified model was 4.4 TECU, which was lower and better than5.1 TECU of the multi-input-multi-output, long short-term memory model and 5.9 TECU of the IRI-2016 model.

关键词： long-short-term memory neural network equatorial ionosphere vertical total electron content vertical total electron content(vTEC)

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Highly efficient nitrogen fixation over S-scheme heterojunction photocatalysts with enhanced active hydrogen supply

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National Science Review 2024年第5期11卷 315-325页

作者： tong bao Yamin Xi Chaoqi zhang Peiyang Du Yitong Xiang Jiaxin Li Ling Yuan Chengzhong Yu Chao Liu School of Chemistry and Molecular Engineering East China Normal University Australian Institute for Bioengineering and Nanotechnology The University of Queensland

Photocatalytic N2fixation is a promising strategy for ammonia（NH3） synthesis;however,it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2adsorption/activation ***,an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2fixation *** CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSxhollow *** the heterojunction,the ele ctronic interaction between ZnS and CoSxcreates electron-deficient Zn sites with enhanced N2chemisorption and electron-sufficient Co sites with active hydrogen supply for N2hydrogenation,cooperatively reducing the energy barrier for *** combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure,an excellent N2fixation performance with a high NH3yield of 1175.37 μmol g-1h-1is *** study provides new insights into the design of hetero junction photocatalysts for N2fixation.

关键词： photocatalysis nitrogen fixation S-scheme heterojunction active hydrogen ammonia

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Vertical MBE growth of Si fins on sub-10 nm patterned substrate for high-performance FinFET technology

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Chinese Physics B 2021年第7期30卷 591-594页

作者： Shuang Sun Jian-Huan Wang bao-tong zhang Xiao-Kang Li Qi-Feng Cai Xia An Xiao-Yan Xu Jian-Jun zhang Ming Li Department of Micro-Nanoelectronics Peking UniversityBeijing 100871China Beijing Laboratory of Future IC Technology and Science Peking UniversityBeijing 100871China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China

A high quality epitaxial Si layer by molecular beam epitaxy(MBE)on Si(001)substrates was demonstrated to fabricate a channel with low density defects for high-performance Fin FET *** order to study the effects of fin width and crystallography orientation on the MBE behavior,a 30 nm thick Si layer was deposited on the top of an etched Si fin with different widths from 10 nm to 50 nm and orientations of 100 and *** result shows that a defect-free Si film was obtained on the fin by MBE,since the etching damage was confined in the bottom of the epitaxial *** addition,the vertical growth of the epitaxial Si layer was observed on sub-10 nm 100 Si fins,and this was explained by a kinetic mechanism.

关键词： sub-10 nm fin molecular beam epitaxy defects mobility

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A novel weld-pool-length monitoring method based on pixel analysis in plasma arc additive manufacturing

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Advances in Manufacturing 2024年第2期12卷 335-348页

作者： bao-Ri zhang Yong-Hua Shi Bionic Robot Research Department Ji Hua LaboratoryFoshan528200GuangdongPeople’s Republic of China Guangdong Provincial Engineering Research Center for Special Welding Technology and Equipment School of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhou510640People’s Republic of China

The real-time monitoring of the weld pool during deposition is important for automatic control in plasma arc additive *** obtain a high deposition accuracy,it is essential to maintain a stable weld pool *** this study,a novel passive visual method is proposed to measure the weld pool *** the proposed method,the image quality was improved by designing a special visual system that employed an endoscope and a *** also includes pixel brightness-based and gradient-based algorithms that can adaptively detect feature points at the boundary when the weld pool geometry *** algorithm can also be applied to materials with different solidification *** was performed to measure the real weld pool length in world coordinates,and outlier rejection was performed to increase the accuracy of the ***,tests were carried out on the intersection component,and the results showed that the proposed method performed well in tracking the changing weld pool length and was applicable to the real-time monitoring of different types of materials.

关键词： Plasma arc additive manufacturing(PAAM) Weld pool geometry Gradient analysis Real-time detection

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Advancements in Humanoid Robots: A Comprehensive Review and Future Prospects

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 301-328页

作者： Yuchuang tong Haotian Liu Zhengtao zhang IEEE CAS Engineering Laboratory for Intelligent Industrial Vision Institute of AutomationChinese Academy of SciencesBeijing 100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China

This paper provides a comprehensive review of the current status, advancements, and future prospects of humanoid robots, highlighting their significance in driving the evolution of next-generation industries. By analyzing various research endeavors and key technologies, encompassing ontology structure,control and decision-making, and perception and interaction, a holistic overview of the current state of humanoid robot research is presented. Furthermore, emerging challenges in the field are identified, emphasizing the necessity for a deeper understanding of biological motion mechanisms, improved structural design,enhanced material applications, advanced drive and control methods, and efficient energy utilization. The integration of bionics, brain-inspired intelligence, mechanics, and control is underscored as a promising direction for the development of advanced humanoid robotic systems. This paper serves as an invaluable resource, offering insightful guidance to researchers in the field,while contributing to the ongoing evolution and potential of humanoid robots across diverse domains.

关键词： Future trends and challenges humanoid robots human-robot interaction key technologies potential applications

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Testing Linearity in Functional Partially Linear Models

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 875-886页

作者： Fan-rong ZHAO bao-xue zhang School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China School of Statistics Capital University of Economics and BusinessBeijing 100070China

For the functional partially linear models including flexible nonparametric part and functional linear part,the estimators of the nonlinear function and the slope function have been studied in existing *** to test the correlation between response and explanatory variables,however,still seems to be ***,a test procedure for testing the linearity in the functional partially linear models will be proposed in this paper.A test statistic is constructed based on the existing estimators of the nonlinear and the slope ***,we prove that the approximately asymptotic distribution of the proposed statistic is a chi-squared distribution under some regularity ***,some simulation studies and a real data application are presented to demonstrate the performance of the proposed test statistic.

关键词： asymptotic theory functional partially linear model Nadaraya-Watson estimate test statistic

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Influence of ecological function protection zone on the water conservation in Gansu-Qinghai Contiguous Region of the upper Yellow River

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Journal of Mountain Science 2024年第4期21卷 1345-1357页

作者： tong Huali CHEN Qingbo zhang Xuan College of Geography and Environmental Science Northwest Normal UniversityLanzhou 730070China Gansu Province Land Use and Comprehensive Improvement Engineering Research Center Lanzhou 730070China

The implementation of Ecological Function Protection Zone(EFPZ)policy is significant for the ecological restoration and conservation of soil and water in the territory *** manuscript analyzed and quantified the impact of EFPZ on the regional water conservation function,based on land use data from 2005,2008,2010,2015 and 2020,by conducting a counterfactual simulation along with the GeoSOS-FLUS model and the InVEST *** results demonstrate that the delineation of EFPZ can significantly influence the water conservation.(1)From 2010 to 2020,as the EFPZ was implemented,the water conservation in the study area was increasing year by year,with a growth rate of 0.03×10^(8) m^(3)∙a^(-1).On the other hand,the simulated water conservation capacity without the implementation of EFPZ decreased year by year,with a decrease rate of 0.01×10^(8) m^(3)∙a^(-1).(2)The EFPZ accounts for only 23%of the total area,but the contribution rate of water conservation reaches 80%.The actual values of water conservation and average water yield per unit pixel in the EFPZ show an increasing trend both internally and externally,while the counterfactual simulation values exhibit a decreasing trend.(3)The water conservation is much higher within the EFPZ than without *** implementation of EFPZ has a significant effect on the improvement of the water conservation capacity in Maqu EFPZ and Yellow River Source *** protection effectiveness should be enhanced in Qilian Mountain EFPZ and afforestation activities need to be carefully considered in Loess Plateau EFPZ.

关键词： Water conservation function Ecological Function Protection Zone Counterfactual simulation Geo SOS-FLUS model InVEST model

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A self-organization formation configuration based assignment probability and collision detection

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Journal of Systems Engineering and Electronics 2024年第1期35卷 222-232页

作者： SONG Wei WANG tong YANG Guangxin zhang Peng School of Harbin Engineering University Harbin 150001China Chinese Aeronautical Establishment Beijing 100010China

The formation control of multiple unmanned aerial vehicles(multi-UAVs)has always been a research *** on the straight line trajectory,a multi-UAVs target point assignment algorithm based on the assignment probability is proposed to achieve the shortest overall formation path of multi-UAVs with low complexity and reduce the energy *** order to avoid the collision between UAVs in the formation process,the concept of safety ball is introduced,and the collision detection based on continuous motion of two time slots and the lane occupation detection after motion is proposed to avoid collision between *** on the idea of game theory,a method of UAV motion form setting based on the maximization of interests is proposed,including the maximization of self-interest and the maximization of formation interest is proposed,so that multi-UAVs can complete the formation task quickly and reasonably with the linear trajectory assigned in ***,through simulation verification,the multi-UAVs target assignment algorithm based on the assignment probability proposed in this paper can effectively reduce the total path length,and the UAV motion selection method based on the maximization interests can effectively complete the task formation.

关键词： straight line trajectory assignment probability collision detection lane occupation detection maximization of interests

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An Online Q-Learning Method for Linear-Quadratic Nonzero-Sum Stochastic Differential Games with Completely Unknown Dynamics

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Journal of Systems Science & Complexity 2024年第5期37卷 1907-1922页

作者： zhang bao-Qiang WANG Bing-Chang CAO Ying School of Control Science and Engineering Shandong UniversityJinan 250000China

In this paper,the authors design a reinforcement learning algorithm to solve the adaptive linear-quadratic stochastic n-players non-zero sum differential game with completely unknown *** each player,a critic network is used to estimate the Q-function,and an actor network is used to estimate the control input.A model-free online Q-learning algorithm is obtained for solving this kind of *** is proved that under some mild conditions the system state and weight estimation errors can be uniformly ultimately bounded.A simulation with five players is given to verify the effectiveness of the algorithm.

关键词： Actor-critic algorithm model-free adaptive control nonzero-sum stochastic game reinforcement learning

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Photoinduced Bending and Curling Motions in Molecular Microcrystals of Naphthyl Meldrum’s Acid Derivative Based on E-to-Z Photoisomerization

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Chemical Research in Chinese Universities 2024年第5期40卷 907-913页

作者： zhang Xiaowen XU Tianyi zhang Chenchen tong Fei Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterFrontiers Science Center for Materiobiology and Dynamic ChemistrySchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai200237P.R.China

Dynamic photoresponsive molecular crystals are promising candidates for making intelligent devices and materials in the ***,we synthesized a new photoactive molecule(E)-2,2-dimethyl-5-[3-(naphthalen-1-yl)allylide]-1,3-dioxane-4,6-dione[(E)-DNADD]that undergoes an E-to-Z photoisomerization in both liquid solution and solids when exposed to visible light(405 nm).Compared to the bulk crystals,the photoresponsive behavior in microcrystals was profoundly *** crystalline(E)-DNADD microplate crystals exhibit robust motions,including bending,curling,and coiling under light *** photoproduct conversion of the photochemical reaction in the microplate is no more than 20%,while the large bending curvature of the coiled illuminated samples was estimated at approximately 150–300 mm−1,comparable to some photoactive *** results indicate that shrinking crystal dimensions can boost the photoresponses in molecular crystals and provide a facile strategy for developing dynamic molecular crystals at the microscopic scale.

关键词： Photochemistry Molecular crystal E-to-Z photoisomerization Photoinduced motion

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