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Charging Properties and Particle Dynamics of Chang’e-5 Lunar Sample in an External Electric Field

Engineering 2024年第11期42卷 267-277页

作者： Junping Gu Xiaoyu Qian Yiwei Liu Qinggong Wang Yiyang Zhang Xuan Ruan Xiangjin Deng Yaowen Lu Jian Song Hui Zhang Yunning Dong Mengmeng Wei Wei Yao Shuiqing Li Weihua Wang Zhigang Zou Mengfei Yang Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Institute of Nuclear and New Energy TechnologyTsinghua UniversityBeijing 100084China Beijing Institute of Spacecraft System Engineering Beijing 100094China Beijing Orient Institute of Measurement and Test Beijing 100086China Institute of Physics Chinese Academy of SciencesBeijing 100190China College of Engineering and Applied Sciences Nanjing UniversityNanjing 210093China China Academy of Space Technology Beijing 100094China

Facing the challenges of in-situ utilization of lunar regolith resources,applying an external electric field to manipulate lunar particles has become a promising method for space particle control,which mainly depends on the particle charging properties in the applied electric *** the surficial lunar regolith samples brought back from the Moon by the Chang’e-5 mission(CE5 LS),this work successively studied their charging properties,particle dynamics,and their collision damages to aerospace materials under the action of an external electric field in high-vacuum *** results indicated that the charging pro-cess and electrostatic projection of lunar regolith particles under high-vacuum conditions were different from those under atmosphere *** particle diameter range of CE5 LS used in the experiment is 27.7-139.0 *** electric field strength of 3-12 kV·cm^(-1),the charge obtained by CE5 LS is 4.8×10^(-15)-4.7×10^(-13) C and the charge-to-mass ratio is 1.2×10^(-5)-6.8×10^(-4) C·kg^(-1).The CE5 LS is easier to be negatively charged in an external electric ***,significant damages were observed on the target impact surfaces,indicating severe influences of lunar regolith particles on aerospace *** work contributes to a more comprehensive understanding of physical mechanisms controlling the lunar regolith shielding and utilization,and will inspire broad efforts to develop the lunar in-situ engi-neering solutions.

关键词： Chang’e-5 lunar regolith sample Charging properties External electric field Particle dynamics Particle collision

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Pressure-assisted Silver Sintering Structure Optimization for Power Modules 5

Pressure-assisted Silver Sintering Structure Optimization fo...

引用

5th International Conference on Optoelectronic science and Materials, ICOSM 2023

作者： Zhang, Hao Xing, Yulong Gao, Lilan Liu, Zheng Tan, Yansong Lu, Guoquan Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin300384 China National Demonstration Center or Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China Tianjin Yixunyuan New Material Technology Co. Ltd. Tianjin300380 China School of Chemical Engineering Tianjin University Tianjin300350 China School of Materials Science and Engineering Virginia Polytechnic Institute and State University BlacksburgVA24061 United States

ISBN: (纸本)9781510674547

As mobile technology evolves from 5G to 6G, the demand for third-generation semiconductors such as SiC with higher power and frequency capabilities is increasing. Silicon Carbide power modules generate significant heat during operation, requiring large-area nano-silver sintering technology to improve module performance and reliability. However, in large-area sintering processes, low exhaust efficiency of solder paste by-products and uneven sintering pressure of the nano-silver paste result in poor sintering quality of the silver layer. This study aims to improve the sintering quality of interconnected silver layers by optimizing the sintering pressure distribution and adding rubber spacers to the sintering structure. ABAQUS was used to quantitatively analyze the effects of pressure methods and gasket material, diameter, and thickness on the stress distribution in the silver layer. Finally, based on the simulation results, an optimized sintering structure was proposed to unify the pressure and reduce the stress concentration in the silver layer, and verified experimentally by sintering tests. Compared with the traditional sintering structure, the application of a 2 mm thick fluoro rubber gasket with the same surface area as the silver layer in the optimized structure reduced the porosity to 2.15% and achieved a more dense sintered silver layer. © 2024 SPIE.

关键词： Finite element method

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High-order Fully Actuated Approach for Output Position Control of Two Mass systems based on Extended State Observer

High-order Fully Actuated Approach for Output Position Contr...

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Fully Actuated system Theory and Applications (CFASTA), Conference on

作者： Ping Li Guang-Ren Duan Bi Zhang Yuzhong Wang Shenzhen Key Laboratory of Control Theory and Intelligent Systems School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China Center for Control Theory and Guidance Technology Harbin Institute of Technology Harbin China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen China

ISBN: (数字)9798350373691

ISBN: (纸本)9798350373707

This paper proposes a high-order fully actuated (HOFA) control approach for the output position control of two-mass systems (TMSs) based on extended state observer (ESO). TMSs belongs to a class of underactuated mechanical systems, which can be converted into an HOFA model using variable elimination. Based on the feature of HOFA model, it is extremely simple to solve the position control law such that a desired tracking error system can be achieved. To handle the control issues of high-order derivatives and unknown disturbances, a linear ESO is employed for state estimation and active disturbance rejection control, where the lumped disturbance is treated as an extended system state. The theoretical stability of control system is analyzed with the help of sliding manifold. Comparative simulations are performed to demonstrate the effectiveness of the proposed approach.

关键词： Robust control Uncertain systems Simulation Position control Observers Control systems Stability analysis

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Investigations of Sodium Droplet Spreading and Evaporation on Surfaces with Different Wettability Based on Lattice Boltzmann Simulations

SSRN

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SSRN 2024年

作者： Tang, Songsheng Guo, Kailun Tian, Zhixing Wang, Mingjun Wang, Chenglong He, Xiaoqiang Su, Guanghui Qiu, Suizheng Tian, Wenxi School of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China Key Lab. of Nuclear Reactor System Design Technology China Nuclear Power Research and Design Institute Chengdu610213 China

The spreading and evaporation of sodium droplets is one of the fundamental phenomena in high-temperature heat pipes. The LBM sodium two-phase flow and phase transition model, which can simulate a huge liquid-vapor density ratio, is first established and validated. Then, the spreading and evaporation processes of sodium droplets on solid walls with different wettability are numerically simulated and analyzed. The main conclusions obtained are as follows: (1) The dimensionless spreading diameter and time of the droplet spreading process conforms to Tanner's power law, and the power exponent has exponential relationship with the equilibrium wetting angle;(2) The maximum dimensionless spreading diameter is negatively and linearly correlated with the equilibrium wetting angle;(3) Evaporation of sodium droplets under constant heat flow conditions shows a mixed pattern. The droplets will be detached from the droplet wall at the late stage of evaporation, and the larger the equilibrium wetting angle the sooner the droplets detach. © 2024, The Authors. All rights reserved.

关键词： Evaporation

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Multi-Resolution Planar Region Extraction for Uneven Terrains

Multi-Resolution Planar Region Extraction for Uneven Terrain...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Yinghan Sun Linfang Zheng Hua Chen Wei Zhang Shenzhen Key Laboratory of Control Theory and Intelligent Systems School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China School of Computer Science University of Birmingham UK

ISBN: (数字)9798350384574

ISBN: (纸本)9798350384581

This paper studies the problem of extracting planar regions in uneven terrains from unordered point cloud measurements. Such a problem is critical in various robotic applications such as robotic perceptive locomotion. While existing approaches have shown promising results in effectively extracting planar regions from the environment, they often suffer from issues such as low computational efficiency or loss of resolution. To address these issues, we propose a multi-resolution planar region extraction strategy in this paper that balances the accuracy in boundaries and computational efficiency. Our method begins with a pointwise classification preprocessing module, which categorizes all sampled points according to their local geometric properties to facilitate multi-resolution segmentation. Subsequently, we arrange the categorized points using an octree, followed by an in-depth analysis of nodes to finish multi-resolution plane segmentation. The efficiency and robustness of the proposed approach are verified via synthetic and real-world experiments, demonstrating our method’s ability to generalize effectively across various uneven terrains while maintaining real-time performance, achieving frame rates exceeding 35 FPS.

关键词： Point cloud compression Deep learning Accuracy Octrees Noise Robustness Real-time systems

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Evolution and Characteristics of Defect Clusters in H2+ Irradiated Al-Based Gd2o3-W Composites Used as Spent Fuel Shielding Materials

SSRN

引用

SSRN 2023年

作者： Wang, Zuojiang Cao, Ziqi Wu, Mengjie Li, Yuanming Ran, Guang College of Energy Xiamen University Fujian Province Xiamen City361102 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China Fujian Provincial Nuclear Energy Engineering Technology Research Center Xiamen361102 China Nuclear Power Institute of China Chengdu610213 China

Al-based composites containing high neutron absorption cross section elements are the most promising shielding materials for spent fuel storage, but their irradiation performance is the key to their long-term service stability. In the present work, an in-situ study on the evolution and characteristics of irradiation defect clusters including dislocation loops, gas bubbles and hydrogen platelets in Al-based Gd2O3-W composites during 30 keV H2+ irradiation was carried out in a transmission electron microscope and analyzed in detail. The delamination of bubbles and the formation of tunnel structure in Al matrix were found for the first time. Hydrogen platelets in Al5W particles was first observed, and their formation and evolution and corresponding mechanism were investigated in detail. Platelets with different orientation had different growth rates, and the relationship between growth rate and dose was constructed. Besides, the irradiation-induced increment of yield strength in Al matrix was estimated. This study will provide new insights for the design and development of new Al-based rare earth composites with high resistance to irradiation damage. © 2023, The Authors. All rights reserved.

关键词： Platelets

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The dynamic compressive properties of magnetorheological plastomers: enhanced magnetic-induced stresses by non-magnetic particles

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Journal of Materials science & technology 2022年第7期102卷 195-203页

作者： Haoming Pang Zhenbang Xu Longjiang Shen Jun Li Junshuo Zhang Zhiyuan Li Shouhu Xuan Xinglong Gong CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of China(USTC)Hefei 230027China Anhui Weiwei Rubber Parts Group Co.Ltd Tongcheng 231400China CAS Key Laboratory of On-orbit Manufacturing and Integration for Space Optics System Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Hunan Bogie Engineering Research Center Zhuzhou 412000China

In this research, a series of hollow glass powder(HGP) reinforced magnetorheological plastomers(MRPs)were prepared to improve the impact resistance of the materials, and the dynamic compressive properties of MRPs under high strain rate were investigated by using a split Hopkinson pressure bar(SHPB)system equipped with a customized magnetic device. Experimental results showed the HGPs greatly enhanced the yield stresses of the MRPs. Especially, for MRPs with 9 vol.% carbonyl iron powders(CIPs), the magnetic-induced yield stress increased from 7.3 MPa to 17.1 MPa(134% increased) by adding 18 vol.%HGPs. The particle structures in MRPs were further simulated and the corresponding intergranular stress was calculated to study the enhancement effect of HGPs. The simulated results showed that more compact structures were formed with the excluded volume caused by secondary HGPs, so the yield stresses of the MRPs increased under a magnetic field. However, when the mass ratio of HGP to CIP was larger than 0.67, HGPs would hinder the formation of chain-like structures and reduce the magneto-mechanical properties. As a result, the replacing of CIPs by HGPs was proven to be an excellent strategy to improve the dynamic properties of MRPs.

关键词： Particle-reinforced composites Stress/strain curves Microstructures Impact behavior Mechanical properties

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Deep Learning-Enabled ISAC-OTFS Pre-equalization design for Aerial-Terrestrial Networks

arXiv

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arXiv 2024年

作者： Wang, Weihao Guo, Jing Wang, Siqiang Wang, Xinyi Yuan, Weijie Fei, Zesong the School of Information and Electronics Beijing Institute of Technology Beijing100081 China the School of System Design and Intelligent Manufacturing The Shenzhen Key Laboratory of Robotics and Computer Vision Southern University of Science and Technology Shenzhen518055 China

Orthogonal time frequency space (OTFS) modulation has been viewed as a promising technique for integrated sensing and communication (ISAC) systems and aerial-terrestrial networks, due to its delay-Doppler domain transmission property and strong Doppler-resistance capability. However, it also suffers from high processing complexity at the receiver. In this work, we propose a novel pre-equalization based ISAC-OTFS transmission framework, where the terrestrial base station (BS) executes pre-equalization based on its estimated channel state information (CSI). In particular, the mean square error of OTFS symbol demodulation and Cramér-Rao lower bound of sensing parameter estimation are derived, and their weighted sum is utilized as the metric for optimizing the pre-equalization matrix. To address the formulated problem while taking the time-varying CSI into consideration, a deep learning enabled channel prediction-based pre-equalization framework is proposed, where a parameter-level channel prediction module is utilized to decouple OTFS channel parameters, and a low-dimensional prediction network is leveraged to correct outdated CSI. A CSI processing module is then used to initialize the input of the pre-equalization module. Finally, a residual-structured deep neural network is cascaded to execute pre-equalization. Simulation results show that under the proposed framework, the demodulation complexity at the receiver as well as the pilot overhead for channel estimation, are significantly reduced, while the symbol detection performance approaches those of conventional minimum mean square error equalization and perfect CSI. Copyright © 2024, The Authors. All rights reserved.

关键词： Channel estimation

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Microstructure and impact toughness of 16MND5 reactor pressure vessel steel manufactured by electrical additive manufacturing

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Journal of Iron and Steel Research International 2020年第8期27卷 992-1004页

作者： Xi-kou He Chang-sheng Xie Li-jun Xiao Ying Luo Di Lu Zheng-dong Liu Xi-tao Wang Institute for Special Steels China Iron and Steel Research InstituteBeijing 100081China Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610041SichuanChina Southern Additive Science and Technology Co. Ltd.Foshan 528225GuangdongChina

Electrical additive manufacturing can improve manufacturing efficiency and reduce the cost of 16MND5 reactor pres-sure vessel steel. Impact tests were conducted to compare the impact toughness of 16MND5 steels manufactured by the electrical additive manufacturing and conventional forging, respectively. It is found that the impact toughness of electrical additive manufacturing specimen was slightly higher than that of conventional forging specimen. The characterizations of microstructure show that there were large ferrites and carbides in electrical additive manufacturing specimen. The fracture mechanisms of electrical additive manufacturing specimen were that microvoids or microcracks were prone to nucleate at the large ferrite/bainite interface and large carbide/bainitic ferrite interface, where the stress concentration was high. In addi-tion, the block size and high-angle grain boundaries played a vital role in hindering crack propagation of electrical additive manufacturing specimen, helping to improve the impact energy and leading to a low ductile–brittle transition temperature. The results suggest that the electrical additive manufacturing technology was an effective method to enhance the impact toughness of 16MND5 steel.

关键词： Electrical additive manufacturing 16MND5 steel Impact toughness Fracture High-angle grain boundary

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High spectro-temporal compression on a nonlinear CMOS-chip

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Light(science & Applications) 2021年第7期10卷 1347-1361页

作者： Ju Won Choi Ezgi Sahin Byoung-Uk Sohn George F.R.Chen Doris K.T.Ng Anuradha M.Agarwal Lionel C.Kimerling Dawn T.H.Tan Photonics Devices and System Group SUTD-MIT International Design CenterSingapore University of Technology and DesignSingapore 487372Singapore Institute of Microelectronics A*STAR(Agency for ScienceTechnology and Research)2 Fusionopolis Way#08-02Innovis TowerSingapore 138634Singapore Microphotonics Center Massachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA 02139USA Materials Research Laboratory Massachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA 02139USA Department of Materials Science and Engineering Massachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA 02139USA

Optical pulses are fundamentally defined by their temporal and spectral *** ability to control pulse properties allows practitioners to efficiently leverage them for advanced metrology,high speed optical communications and attosecond ***,we report 11×temporal compression of 5.8 ps pulses to 0.55 ps using a low power of 13.3 *** result is accompanied by a significant increase in the pulse peak power by 9.4×.These results represent the strongest temporal compression demonstrated to date on a complementary metal–oxide–semiconductor(CMOS)*** addition,we report the first demonstration of on-chip spectral compression,3.0×spectral compression of 480 fs pulses,importantly while preserving the pulse *** strong compression achieved at low powers harnesses advanced on-chip device design,and the strong nonlinear properties of backend-CMOS compatible ultra-silicon-rich nitride,which possesses absence of two-photon absorption and 500×larger nonlinear parameter than in stoichiometric silicon nitride *** demonstrated work introduces an important new paradigm for spectro-temporal compression of optical pulses toward turn-key,on-chip integrated systems for all-optical pulse control.

关键词： pulse optical nonlinear

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