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An integrative mathematical model of microwave ion thruster for mHz-frequency thrust noise analysis

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Chinese Journal of Aeronautics 2024年第4期37卷 121-136页

作者： Xiang niu Hui LIU Daren yu Plasma Propulsion Laboratory Harbin Institute of TechnologyHarbin 150001China

Many high-precision space missions need thrusters to produce thrust with low noise to compensate for disturbances and ensure satellite platform stability. Microwave ion thruster is characterized with a wide thrust range and potential for these missions. A cost-effective and accurate mathematical model is crucial for mHz-frequency thrust noise analysis and feedback controller design. The Particle-In-Cell(PIC) and global models are two common simulation tools. The PIC model is characterized with high accuracy but huge computation cost, which is difficult to analyze long-time performance characteristics. Now, the global model is only used for the discharge chamber with low accuracy and cannot reflect ion extraction properties. In this paper, an integrative mathematical model is built for a 1-cm microwave ion thruster and can reflect ion beamlet divergence and impingement on the Accelerator Grid(AG). Simulation results show good agreement with experiments at 0.06 sccm. However, the model demonstrates worse consistency with experiments when the flux increases to 0.1 sccm, which may be because the influence of neutral gas on the Electron Cyclotron Resonance(ECR) is not considered in the model. A long-time(1000 s) simulation is conducted with this model under 35 μN. It takes 3 hrs, and the thrust noise reaches 1 μN/Hz^(0.5) at 1 mHz.

关键词： Electric propulsion Microwave ion thruster Integrative model Sheath property Ion beamlet divergence Thrust noise Plasma

A unified pre-training and adaptation framework for combinatorial optimization on graphs

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Science China Mathematics 2024年第6期67卷 1439-1456页

作者： Ruibin Zeng Minglong Lei Lingfeng niu lan Cheng School of Computer Science and Technology University of Chinese Academy of SciencesBeijing100049China Faculty of Information Technology Beijing University of TechnologyBeijing100124China School of Economics and Management University of Chinese Academy of SciencesBeijing100190China School of Mathematics and Statistics Central South UniversityChangsha410075China

Combinatorial optimization(CO)on graphs is a classic topic that has been extensively studied across many scientific and industrial fields.Recently,solving CO problems on graphs through learning methods has attracted great attention.Advanced deep learning methods,e.g.,graph neural networks(GNNs),have been used to effectively assist the process of solving COs.However,current frameworks based on GNNs are mainly designed for certain CO problems,thereby failing to consider their transferable and generalizable abilities among different COs on graphs.Moreover,simply using original graphs to model COs only captures the direct correlations among objects,which does not consider the mathematical logicality and properties of COs.In this paper,we propose a unified pre-training and adaptation framework for COs on graphs with the help of the maximum satisfiability(Max-SAT)problem.We first use Max-SAT to bridge different COs on graphs since they can be converted to Max-SAT problems represented by standard formulas and clauses with logical information.Then we further design a pre-training and domain adaptation framework to extract the transferable and generalizable features so that different COs can benefit from them.In the pre-training stage,Max-SAT instances are generated to initialize the parameters of the model.In the fine-tuning stage,instances from CO and Max-SAT problems are used for adaptation so that the transferable ability can be further improved.Numerical experiments on several datasets show that features extracted by our framework exhibit superior transferability and Max-SAT can boost the ability to solve COs on graphs.

关键词： combinatorial optimization graph neural networks domain adaptation maximum satisfiability problem

Highly Thermoconductive,Strong Graphene‑Based Composite Films by Eliminating Nanosheets Wrinkles

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Nano-Micro Letters 2024年第1期16卷 328-340页

作者： Guang Xiao Hao Li Zhizhou yu Haoting niu Yagang Yao College of Engineering and Applied Sciences Jiangsu Key Laboratory of Artificial Functional Materialsand Collaborative Innovation Center of Advanced MicrostructuresNational Laboratory of Solid State MicrostructuresNanjing UniversityNanjing 210093People’s Republic of China Institute of Laser Manufacturing Henan Academy of SciencesZhengzhou 450052People’s Republic of China Center for Quantum Transport and Thermal Energy Science School of Physics and TechnologyNanjing Normal UniversityNanjing 210023People’s Republic of China

Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices.However,when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites,capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying,which greatly reduces the thermal conductivity of the composites.Herein,graphene nanosheets/aramid nanofiber(GNS/ANF)composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds andπ-πinteractions.The in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets,thereby creating a fast in-plane heat transfer channel.The composite films(GNS/ANF-60 wt%)with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity(146 W m^(−1)K^(−1))and tensile strength(207 MPa).The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones,showing promising applications in the thermal management of high-power electronic devices.

关键词： Graphene Aramid nanofiber Wrinkles elimination In-plane stretching Thermal conductivity

Intraspecific floral colour variation in three Pedicularis species

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Plant Diversity 2024年第2期46卷 274-279页

作者： Qiu-yu Zhang Zhe Chen Hang Sun Yang niu State Key Laboratory of Plant Diversity and Specialty Crops Kunming Institute of BotanyChinese Academy of SciencesKunming 650201YunnanChina University of Chinese Academy of Sciences Beijing 100049China

Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging,reducing reproductive interference in natural communities.The extent of flower constancy is largely determined by the floral traits of co-flowering species.Both higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower constancy.However,previous studies mainly focused on interspecific difference,and the intraspecific variation(consistency)of floral traits received much less attention.We hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering congeners.We investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19communities composed of either single or multiple Pedicularis species.Colour was quantified using image-based colour analysis as perceived by pollinators.We found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees,implying strongly constrained by the visual selection by pollinators.Contrary to the hypothesis,there is no significant difference in intraspecific floral colour variation between different community contexts.It may be due to the relatively large interspecific floral colour differences of most co-flowering species.The influence of community context on intraspecific variation may be reflected in floral traits other than colours.

关键词： Flower constancy Floral colour variation Plantepollinator interactions Pollinator vision

Fabrication of Molecularly Imprinted Electrospun Nanofibers with Mono-amidoxime Functional Ligand for Efficient Decontamination of Toxic Organophosphates

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Chinese Journal of Polymer Science 2024年第4期42卷 446-456页

作者： lan Wang Peng Jiang Ya-Lin niu Jun-Peng Cao Tian-Ying Guo Key Laboratory of Functional Polymer Materials Ministry of EducationInstitute of Polymer ChemistryCollege of Chemistry and Frontier Science Center for the Creation of New Organic SubstancesNankai UniversityTianjin300071China

There is an urgent imperative to discover practical and efficacious artificial catalysts for the expeditious decontamination of toxic organophosphates. Herein, we propose a novel molecularly imprinted approach utilizing electrospun fiber scaffolds. Specifically, an amidoxime-based functional polymer (PMAOX) has been synthesized, which contains amidoxime groups that can act as nucleophiles and ligands for the formation of catalytic active sites. This polymer was blended with polyacrylonitrile (PAN), a well-processable material, to prepare a nanofiber mat using electrospinning techniques. Then, the amidoxime side groups on fiber surface were further cross-linked after the molecular coordination of templates to complete the molecularly imprinting process. This approach can not only enhance the content of functional molecularly imprinted polymers without affecting structural stability, but also combines surface MI technology to fully expose and leverage the advantages of active sites. The as prepared molecularly imprinted electrospun nanofibers MIF-Zn-PMAOX/PAN-6/4 catalyzes the degradation of paraoxon with a half-life of 32 min, and MIF-Ag-PMAOX/PAN catalyzes the degradation of parathion with a half-life of 18 min. The maximum catalytic rate evidence rate enhancements nearly 3700-fold of the self-hydrolysis. Thus, the mono-amidoxime based molecularly imprinted fibers demonstrate the versatility and superiority as self-detoxifying for organophosphates.

关键词： Organophosphateshydrolysis Electrospinning Molecular imprinting

A Brief of Cold Spell Warning Actions of the National Meteorological Center of China Meteorological Administration

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China CDC weekly 2024年第5期6卷 88-91页

作者： Taiyuan Zhang Mengxue Zhang Qiutong Li yu lan Huafeng Meteorological Media Group of China Meteorological Administration(CMA) BeijingChina National Institute of Environmental Health Chinese Center for Disease Control and PreventionBeijingChina The National Meteorological Center of China Meteorological Administration(CMA) BeijingChina

The“Outline for High-Quality Development of Meteorology(2022-2035)”was published by the State Council of the People’s Republic of China in April 2022(1).This publication highlights the essential role of meteorological disaster warnings,particularly cold spell warnings,in preventing and mitigating disasters.The outline also sets forth stricter expectations for enhancing the overall capacity of society in terms of meteorological disaster preparedness and response.

关键词： disaster meteorological warning

Emerging mechanisms and implications of c GAS-STING signaling in cancer immunotherapy strategies

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Cancer Biology & Medicine 2024年第1期21卷 45-64页

作者： Jiawen Zhang Sihui yu Qiao Peng Ping Wang lan Fang Tongji University Cancer Center Shanghai Tenth People’s HospitalSchool of MedicineTongji UniversityShanghai 200072China Reproductive Medicine Center Department of Obstetrics and GynecologyShanghai General HospitalShanghai Jiao Tong University School of MedicineShanghai 201620China Department of Obstetrics and Gynecology Zhongshan HospitalFudan UniversityShanghai 200032China

The intricate interplay between the human immune system and cancer development underscores the central role of immunotherapy in cancer treatment.Within this landscape,the innate immune system,a critical sentinel protecting against tumor incursion,is a key player.The cyclic GMP-AMP synthase(c GAS)and stimulator of interferon genes(STING)pathway has been found to be a linchpin of innate immunity:activation of this signaling pathway orchestrates the production of type I interferon(IFN-α/β),thus fostering the maturation,differentiation,and mobilization of immune effectors in the tumor microenvironment.Furthermore,STING activation facilitates the release and presentation of tumor antigens,and therefore is an attractive target for cancer immunotherapy.Current strategies to activate the STING pathway,including use of pharmacological agonists,have made substantial advancements,particularly when combined with immune checkpoint inhibitors.These approaches have shown promise in preclinical and clinical settings,by enhancing patient survival rates.This review describes the evolving understanding of the c GAS-STING pathway's involvement in tumor biology and therapy.Moreover,this review explores classical and non-classical STING agonists,providing insights into their mechanisms of action and potential for optimizing immunotherapy strategies.Despite challenges and complexities,the c GAS-STING pathway,a promising avenue for enhancing cancer treatment efficacy,has the potential to revolutionize patient outcomes.

关键词： cGAS-STING pathway type I interferon cyclic dinucleotide STING agonist cancer immunotherapy

Demonstration of high-dimensional controlled quantum teleportation for the first time

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Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 163-164页

作者： yu-Bo Sheng lan Zhou College of Electronic and Optical Engineering and College of Flexible Electronics(Future Technology) Nanjing University of Posts and TelecommunicationsNanjing 210023China College of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China

Controlled quantum teleportation(CQT) [1] is the tripartite version of quantum teleportation and it allows the teleportation of an unknown quantum state under the control of a third party. Compared with low-dimensional counterparts,high-dimensional CQT can exhibit larger information transmission capacity and a higher control power [2,3].

关键词： quantum dimensional high

Model for estimating the weight-loss ratio of damaged Korla fragrant pears

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International Journal of Agricultural and Biological Engineering 2024年第1期17卷 261-266页

作者： Yang Liu yurong Tang Hong Zhang Hao niu Haipeng lan College of Mechanical and Electrical Engineering Tarim UniversityAlaer 843300XinjiangChina College of Water Resources and Architectural Engineering Tarim UniversityAlaer 843300XinjiangChina

To predict the weight-loss ratio of Korla fragrant pears effectively,improve commodity value and study the variation laws of the weight-loss ratio of damaged fragrant pears during storage,this study predicted the weight-loss ratio of fragrant pears by utilizing the generalized regression neural network(GRNN),support vector regression(SVR),partial least squares regression(PLSR)and error back propagation neural network(BPNN).The prediction performances of GRNN,SVR,PLSR and BPNN models were compared comprehensively,and the optimal model was determined.In addition,the optimal prediction model was verified.The results show that weight-loss ratio of fragrant pears increases gradually with the extension of storage time.During storage,the weight-loss ratio of fragrant pears is positively related to the degree of damage.The trained GRNN,SVR,PLSR and BPNN models can be used to predict the weight-loss ratio of fragrant pears.The BPNN model is the most accurate in predicting the weight-loss ratio of damaged fragrant pears(R^(2)=0.9929;RMSE=0.2138).It has also been proved to have good predictive effect in production practice(R^(2)=0.9377,RMSE=0.7138).The research findings can provide references to predict the delivery quality and time of delivery of Korla fragrant pears.

关键词： Korla fragrant pears weight-loss ratio damages storage time