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Optimization of body configuration and joint-driven attitude stabilization for transformable spacecraft under solar radiation pressure

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Astrodynamics 2024年第1期8卷 47-60页

作者： Yuki Kubo Toshihiro Chujo Institute of Space and Astronautical science Japan Aerospace Exploration AgencyKanagawa252-5210Japan Department of Mechanical Engineering Tokyo Institute of TechnologyTokyo152-8550Japan

The solar sail is one of the most promising space exploration systems due to its theoretically infinite specific impulse achieved through solar radiation pressure(SRP).Recently,researchers have proposed“transformable spacecraft”capable of actively reconfiguring their body configurations using actuatable *** spacecraft,if used similarly to solar sails,are expected to significantly enhance orbit and attitude control capabilities owing to their high redundancy in control degrees of ***,controlling them becomes challenging due to their large number of inputs,leading previous researchers to impose strong constraints to limit their potential control *** study focuses on novel attitude control techniques for transformable spacecraft under *** developed two methods,namely,joint angle optimization to obtain arbitrary SRP force and torque,and momentum damping control driven by joint angle *** proposed methods are formulated in a general manner and can be applied to any transformable spacecraft comprising front faces that can predominantly receive the SRP on each *** validity of our proposed method is confirmed through numerical *** study contributes to making most of the high control redundancy of transformable spacecraft without the need for expendable propellants,thus significantly enhancing the orbit and attitude control capabilities.

关键词： solar sail transformable spacecraft attitude-joint coupled motion attitudestabilization

Low-Energy Spin Excitations in Detwinned FeSe

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Chinese Physics Letters 2024年第6期41卷 112-118页

作者：刘瑞鲜 Mitsutaka Nakamura Kazuya Kamazawa 鲁兴业 Center for Advanced Quantum Studies School of Physics and AstronomyBeijing Normal UniversityBeijing 100875China J-PARC Center Japan Atomic Energy Agency(JAEA)TokaiIbaraki 319-1195Japan Research Center for Neutron science and technology Comprehensive Research Organization for Science and SocietyTokaiIbaraki 319-1106Japan

Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high-Tc *** iron-based superconductors,spin excitations at low energy range,especially the spin-resonance mode at ER~5kBTc,are important for understanding the ***,we use inelastic neutron scattering(INS)to investigate the symmetry and in-plane wave-vector dependence of low-energy spin excitations in uniaxial-strain detwinned Fe *** low-energy spin excitations(E3 meV reported in a prior INS ***,our results reveal an isotropic spin resonance in the superconducting state,which is consistent with the s±wave pairing *** slightly higher energy,low-energy spin excitations become highly *** full width at half maximum of spin excitations is elongated along the transverse *** Q-space isotropic spin resonance and highly anisotropic low-energy spin excitations could arise from dyz intra-orbital selective Fermi surface nesting between the hole pocket aroundΓpoint and the electron pockets centered at MX point.

关键词： excitation symmetry slightly

HEN:a novel hybrid explainable neural network based framework for robust network intrusion detection

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science China(Information sciences) 2024年第7期67卷 72-90页

作者： Wei WEI Sijin CHEN Cen CHEN Heshi WANG Jing LIU Zhongyao CHENG Xiaofeng ZOU School of Computer science and Engineering Xi'an University of TechnologyShaanxi Key Laboratory for Network Computing and Security Technology School of Computer science and technology Wuhan University of Science and Technology School of Future technology South China University of Technology Shenzhen Research Institute of Hunan University School of Computer science Hunan University of Technology and Business Institute for Infocomm Research (I2R) Agency for Science Technology and Reseach (A*STAR)

With the rapid development of network technology and the automation process for 5G, cyberattacks have become increasingly complex and threatening. In response to these threats, researchers have developed various network intrusion detection systems(NIDS) to monitor network traffic. However, the incessant emergence of new attack techniques and the lack of system interpretability pose challenges to improving the detection performance of NIDS. To address these issues, this paper proposes a hybrid explainable neural network-based framework that improves both the interpretability of our model and the performance in detecting new attacks through the innovative application of the explainable artificial intelligence(XAI)method. We effectively introduce the Shapley additive explanations(SHAP) method to explain a light gradient boosting machine(Light GBM) model. Additionally, we propose an autoencoder long-term short-term memory(AE-LSTM) network to reconstruct SHAP values previously generated. Furthermore, we define a threshold based on reconstruction errors observed during the training phase. Any network flow that surpasses the specified threshold is classified as an attack flow. This approach enhances the framework's ability to accurately identify attacks. We achieve an accuracy of 92.65%, a recall of 95.26%, a precision of 92.57%,and an F1-score of 93.90% on the dataset NSL-KDD. Experimental results demonstrate that our approach generates detection performance on par with state-of-the-art methods.

关键词： explainable artificial intelligence light gradient boosting machine machine learning network intrusion detection Shapley additive explanation hybrid explainable neural network (HEN)

Recent Advances in In-Memory Computing:Exploring Memristor and Memtransistor Arrays with 2D Materials

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Nano-Micro Letters 2024年第7期16卷 1-30页

作者： Hangbo Zhou Sifan Li Kah-Wee Ang Yong-Wei Zhang Institute of High Performance Computing(IHPC) Agency for ScienceTechnology and Research(A*STAR)1 Fusionopolis Way#16-16 ConnexisSingapore 138632Republic of Singapore Department of Electrical and Computer Engineering National University of Singapore4 Engineering Drive 3Singapore 117583Republic of Singapore Institute of Materials Research and Engineering Agency for ScienceTechnology and Research(A*STAR)2 Fusionopolis WaySingapore 138634Republic of Singapore

The conventional computing architecture faces substantial chal-lenges,including high latency and energy consumption between memory and processing *** response,in-memory computing has emerged as a promising alternative architecture,enabling computing operations within memory arrays to overcome these *** devices have gained significant attention as key components for in-memory computing due to their high-density arrays,rapid response times,and ability to emulate biological *** these devices,two-dimensional(2D)material-based memristor and memtransistor arrays have emerged as particularly promising candidates for next-generation in-memory computing,thanks to their exceptional performance driven by the unique properties of 2D materials,such as layered structures,mechanical flexibility,and the capability to form *** review delves into the state-of-the-art research on 2D material-based memristive arrays,encompassing critical aspects such as material selection,device perfor-mance metrics,array structures,and potential ***,it provides a comprehensive overview of the current challenges and limitations associated with these arrays,along with potential *** primary objective of this review is to serve as a significant milestone in realizing next-generation in-memory computing utilizing 2D materials and bridge the gap from single-device characterization to array-level and system-level implementations of neuromorphic computing,leveraging the potential of 2D material-based memristive devices.

关键词： 2D materials Memristors Memtransistors Crossbar array In-memory computing

Nanophononic metamaterials induced proximity effect in heat flux regulation

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Frontiers of physics 2024年第2期19卷 149-156页

作者： Jian Zhang Haochun Zhang Gang Zhang School of Energy science and Engineering Harbin Institute of TechnologyHarbin 150001China Institute of High Performance Computing Agency for ScienceTechnology and Research(A*STAR)Singapore 138632Singapore

Recent studies have shown that the construction of nanophononic metamaterials can reduce thermal conductivity without affecting electrical properties,making them promising in many fields of application,such as energy conversion and thermal ***,although extensive studies have been carried out on thermal conductivity reduction in nanophononic metamaterials,the local heat flux characteristic is still *** this work,we construct a heat flux regulator which includes a silicon nanofilm with silicon *** regulator has remarkable heat flux regulation ability,and various impacts on the regulation ability are ***,even in the region without nanopillars,the local heat current is still lower than that in pristine silicon nanofilms,reduced by the neighboring nanopillars through the thermal proximity *** combine the analysis of the phonon participation ratio with the intensity of localized phonon modes to provide a clear *** findings not only provide insights into the mechanisms of heat flux regulation by nanophononic metamaterials,but also will open up new research directions to control local heat flux for a broad range of applications,including heat management,thermoelectric energy conversion,thermal cloak,and thermal concentrator.

关键词： nanophononic metamaterials proximity effect

Enabling an Inorganic-Rich Interface via Cationic Surfactant for High-Performance Lithium Metal Batteries

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Nano-Micro Letters 2024年第8期16卷 1-17页

作者： Zejun Sun Jinlin Yang Hongfei Xu Chonglai Jiang Yuxiang Niu Xu Lian Yuan Liu Ruiqi Su Dayu Liu Yu Long Meng Wang Jingyu Mao Haotian Yang Baihua Cui Yukun Xiao Ganwen Chen Qi Zhang Zhenxiang Xing Jisheng Pan Gang Wu Wei Chen Department of Chemistry National University of Singapore3 Science Drive 3Singapore 117543Singapore agency for science Technology and Research(A*STAR)Institute of High-Performance Computing1 Fusionopolis Way#16‑16 ConnexisSingapore 138632Singapore Department of Physics National University of Singapore2 Science Drive 3Singapore 117542Singapore Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou 350207People’s Republic of China agency for science Technologyand Research(A*STAR)Institute of Materials Research and EngineeringInnovis2 Fusionopolis Way#08‑03Singapore 138634Singapore

An anion-rich electric double layer(EDL)region is favorable for fabricating an inorganic-rich solid-electrolyte interphase(SEI)towards stable lithium metal anode in ester ***,cetyltrimethylammonium bromide(CTAB),a cationic surfactant,is adopted to draw more anions into EDL by ionic interactions that shield the repelling force on anions during lithium *** situ electrochemical surface-enhanced Raman spectroscopy results combined with molecular dynamics simulations validate the enrichment of NO_(3)^(−)/FSI−anions in the EDL region due to the positively charged CTA^(+).In-depth analysis of SEI structure by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry results confirmed the formation of the inorganic-rich SEI,which helps improve the kinetics of Li^(+)transfer,lower the charge transfer activation energy,and homogenize Li *** a result,the Li||Li symmetric cell in the designed electrolyte displays a prolongated cycling time from 500 to 1300 h compared to that in the blank electrolyte at 0.5 mA cm^(-2) with a capacity of 1 mAh cm^(-2).Moreover,Li||LiFePO_(4) and Li||LiCoO_(2) with a high cathode mass loading of>10 mg cm^(-2) can be stably cycled over 180 cycles.

关键词： Cationic surfactant Lithium nitrate additive Solid-electrolyte interphase Electric double layer Lithium metal batteries

Combinations of electron and proton donors in transition-metal complex mediated nitrogen reduction reactions

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science China Chemistry 2024年第7期67卷 2136-2154页

作者： Delong Han Li Yang Hao Huang Priyanka Chakraborty Shashikant U.Dighe Kuo-Wei Huang KAUST Catalysis Center and Division of Physical science and Engineering King Abdullah University of Science and TechnologyThuwal 23955Saudi Arabia agency for science Technologyand ResearchInstitute of Materials Research and Engineering and Institute of Sustainability for ChemicalsEnergy and EnvironmentSingapore 138634Singapore

Nitrogen fixation is a complex process involving the transfer of six electrons and *** from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to reduce nitrogen(N_(2)),homogeneous transition metal complex-catalyzed N_(2)reduction reactions(NRR)employ an array of electron and proton donors or even electron donors combined with *** the synthesis of diverse catalytic progress,the categories of donors have seen rapid ***,existing literature only provides summaries regarding the metal,ligands,and *** the significance of electron and proton donor combinations in nitrogen reduction reactions,no literature has thoroughly reviewed this ***,we hereby compiled a comprehensive list of commonly used reagents in N_(2)reduction and classified them according to their specific donor *** review presents clear and organized information about these combinations,along with a summary of their general performance trend in NRR with related ***,we conclude the discussion by highlighting key points for researchers to consider when selecting catalysts and donor combinations,with the ultimate goal of advancing the field of nitrogen fixation.

关键词： dinitrogen reduction reaction reducing donor combination transition metal complexes homogeneous catalysis

An Experimental Study on Response and Control of a Flapping-Wing Aerial Robot Under Wind Gusts

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Journal of Bionic Engineering 2024年第1期21卷 209-223页

作者： Kazuki Shimura Hikaru Aono Chang-kwon Kang Graduate School of science and technology Shinshu University3-15-1 TokidaUedaNagano 3868567Japan Department of Mechanical Engineering and Robotics 3-15-1 TokidaUedaNagano 3868567Japan Department of Mechanical and Aerospace Engineering University of Alabama in HuntsvilleTechnology Hall N266HuntsvilleAL35899USA

Bioinspired flapping-wing micro-air-vehicles(FWMAVs)have the potential to be useful aerial tools for gathering information in various *** recent advancements in manufacturing technologies and better understanding of aerodynamic mechanisms behind of the flapping flight,outdoor flights have become a ***,to fully realize the potential of FWMAVs,further improvements are necessary,particularly in terms of stability and robustness under gusty *** this study,the response and control of a tailless two-winged FWMAV under the wind gusts are *** experiments are conducted with a one-degree-of-freedom gimbal to focus on effects of wind gusts on the rotational motion of the ***-derivative and sliding-mode controls are adopted for the attitude *** present that the body angles changed in time and reached approximately 50°at the maximum due to the wing *** sliding-mode controller can more effectively control the rotational angle in the presence of disturbances and both the wing speed and changes in wind speed have an impact on the effectiveness of attitude *** results contribute to the development of of tailless two-winged,single-motor driven FWMAVs in terms of the design of attitude controller and testing apparatus.

关键词： Flapping-wing micro-air vehicles Sliding-mode control Pitch and roll angle-Wind gus

Numerical analysis of a projecting wall type oscillating water column(PW-OWC)wave energy converter in regular waves

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Journal of Hydrodynamics 2024年第3期36卷 479-491页

作者： Lei Tan Ruiyuan Chang Tomoki Ikoma Department of Oceanic Architecture and Engineering College of Science and TechnologyNihon UniversityChibaJapan

Oscillating water column(OWC)based wave energy absorption devices are classic which have been widely used for harnessing ocean wave *** paper presents a numerical study on a projecting wall(PW)type OWC wave energy converter in regular *** computational fluid dynamics(CFD)modelling of a stationary floating PW-OWC model in a three-dimensional wave flume is achieved by the software *** analyses are carried out based on CFD simulations and the linear potential flow solutions with modifications to account for turbine-induced *** present numerical solutions are validated against our previous experimental *** is found that both the CFD and modified linear potential flow predictions are in reasonably good agreements with the experimental data in the first order results of OWC and air pressure *** the nonlinear responses are included in the result,the modified linear potential flow solution is found to slightly under-estimate the wave energy conversion performance at long *** the airflows above and below the chamber orifice,the CFD results suggest that they are almost unidirectional,oscillating in not only the base frequency but also subharmonic and ultraharmonic *** evolution of the OWC responses during an entire period and the phase analysis based on CFD simulations are *** phase results provide the crucial evidence to the reasonability of the physics-based modification of the potential flow model in modelling of *** present results and analysis are expected to be beneficial to the understanding on the physical mechanism of OWCs and the design of phase control strategies.

关键词： Computational fluid dynamics(CFD)simulation hydrodynamic analysis oscillating water column(OWC)damping orifice airflow phase difference