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Progress in Electromagnetic Research Symposium (PIERS)

作者： Yanfeng Wang Qihua Wu Tiehua Zhao Xiaobin Liu Feng Zhao Shunping Xiao State Key Laboratory of Complex Electromagnetic Environmental Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology China

ISBN: (数字)9798350375909

ISBN: (纸本)9798350375916

Range gate pull-off (RGPO) Jamming disrupts tracking capability of radar system by strategically increasing the latency of radar signal. Hence this kind of active deception jamming is widely adopted. The quantitative assessment and evaluation of RGPO Jamming effects on radar systems is of great significance for enhancing radar anti-jamming capabilities. However, difficulties exist in establishing a mathematical model for analyzing the jamming effects through theoretical analyses. Both the complexity of different radar systems and randomness of radar tracking processes add to this challenge. These factors result in substantial workload to analyze jamming effects. Considering these challenges, a modelling method for RGPO effects on radar based on digital simulation results is introduced in this study. Firstly, the radar range tracking model was established. Through the qualitative analyses of the process of RGPO jamming effect and the principle of affecting the tracking loop, it was found that the rate of a successful pulling off would show a precipitous drop after the pulling speed exceeds a certain threshold. This conclusion was verified in the simulation results of the RGPO effect simulation system. On this basis, to build the relationship between the maximum pull-off speed and the Jamming-to-Signal Ratio (JSR), a modelling method based on spline interpolation and least squares fitting was proposed in this study. The work contributes to a deeper understanding of the impact of RGPO Jamming on radar tracking, and provides valuable insights for bolstering radar countermeasures.

关键词： Interpolation Analytical models Tracking loops Fitting Digital simulation Radar Logic gates

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Dual-Polarized Wideband Wide-Beam Millimeter-Wave Magneto-Electric Dipole Antenna

Dual-Polarized Wideband Wide-Beam Millimeter-Wave Magneto-El...

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Cross Strait Quad-Regional Radio science and Wireless technology Conference (CSRWTC)

作者： Linglong Gou Jing Ma Bin Shi Zhongbo Zhu Lin Peng Key laboratory of Microwave and Optical Wave Application Technology Guilin University of Electronic Technology Guilin Guangxi China The Science and Technology on special system simulation laboratory Beijing Simulation Center Beijing China The National Key Laboratory of Science and Technology on Space Microwave Xi'an China

In this manuscript, a dual-polarized wideband wide beamwidth magneto-electric (ME) dipole antenna for millimeter-wave mobile communication is proposed. As can be seen from the simulation results, this design exhibits excellent performance. Owing to the mutual resonances of the magnetic dipole and the electric dipole, large bandwidths of 64.8% and 59% (18.4 GHz-33 GHz and 17.29 GHz-33.9 GHz) are obtained for the two polarizations, respectively. The isolation between the two ports is greater than 25 dB. By loading metal vias, the antenna's beamwidth is widened to more than 100° through the whole operating band. The antenna size is $\mathbf{5}\mathbf{mm}\times \mathbf{5}\mathbf{mm}\times \mathbf{1.72}\mathbf{mm}$ , and this compact structure is quite suitable for using in beam scanning antennas.

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Large Eddy simulation of Flow and Heat Transfer Performance in Periodically Inward Corrugated Tubes

SSRN

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SSRN 2023年

作者： Zhong, Yuzhou Song, Yueheng Zhao, Lei Mi, Fei Zhao, Jingquan Zhu, Xiaowei School of Aeronautic Science and Engineering Beihang University Beijing100191 China Science & Technology on Complex Aviation System Simulation Laboratory Beijing100070 China Co. Ltd. Henan453049 China

Corrugated tubes are extensively unitized in enhancing heat transfer within tubular heat exchange devices. The efficiency of these corrugated tubes is closely linked to the geometric characteristics of the surface corrugations. In this study, we conducted an extensive series of Large Eddy simulations on a representative type of enhanced tube featuring periodic inward corrugations (PIC). Our goal was to compile a comprehensive and precise dataset of the thermal and hydraulic properties specific to this design. The key design parameters that define the corrugated patterns are corrugation height, corrugation width, and the length of the straight section. We systematically explored these parameters to understand their impact on heat transfer and fluid dynamics. Among these parameters, corrugation height has been identified as the most influential factor affecting flow and heat transfer properties. As the corrugation height varies from 1/8D to 3/8D, we observed a substantial increase in the friction factor and Nusselt number by a factor of 209 and 5, respectively, at Re = 1000;while the critical Reynolds number decreased roughly from 800 to 100. These findings underscore the significant role of corrugation height in shaping the flow and heat transfer performance of PIC tubes. The other two parameters, corrugation width and straight section length, were also found to be crucial in determining the overall heat transfer coefficient and pressure drop. The results of our study suggest that when utilizing this type of corrugated tubes, careful consideration is required to strike an optimal balance between heat transfer efficiency and pressure loss. The large-sets LES results presented in this paper can serve as valuable inputs for optimizing the design of PIC tubes. © 2023, The Authors. All rights reserved.

关键词： Large eddy simulation

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Health benefits from the rapid reduction in ambient exposure to air pollutants after China's clean air actions:progress in efficacy and geographic equality

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National science Review 2024年第2期11卷 103-113页

作者： Tao Xue Ruohan Wang Meng Wang Yanying Wang Dan Tong Xia Meng Conghong Huang Siqi Ai Fangzhou Li Jingyuan Cao Mingkun Tong Xueqiu Ni Hengyi Liu Jianyu Deng Hong Lu Wei Wan Jicheng Gong Shiqiu Zhang Tong Zhu Institute of Reproductive and Child Health National Health Commission Key Laboratory of Reproductive Health/Department of Epidemiology and Biostatistics Ministry of Education Key Laboratory of Epidemiology of Major Diseases(PKU) School of Public Health Peking University Health Science Centre State Environmental Protection Key Laboratory of Atmospheric Exposure and Health Risk Management and Center for Environment and Health Peking University Advanced Institute of Information Technology Peking University Department of Epidemiology and Environmental Health School of Public Health and Health ProfessionsUniversity at Buffalo State Key Joint Laboratory of Environment Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking University Department of Earth System Science Tsinghua University School of Public Health Key Laboratory of Public Health Safety of the Ministry of Education and Key Laboratory of Health Technology Assessment of the Ministry of HealthFudan University College of Land Management Nanjing Agricultural University National&Local Joint Engineering Research Center for Rural Land Resources Use and Consolidation Clean Air Asia

Clean air actions （CAAs） in China have been linked to considerable benefits in public ***,whether the beneficial effects of CAAs are equally distributed geographically is *** high-resolution maps of the distributions of major air pollutants (fine particulate matter[PM2.5]and ozone[O3]) and population,we aimed to track spatiotemporal changes in health impacts from,and geographic inequality embedded in,the reduced exposures to PM2.5and O3from 2013 to *** used a method established by the Global Burden of Diseases *** analyzing the changes in loss of life expectancy（LLE） attributable to PM2.5and O3,we calculated the gain of life expectancy （GLE） to quantify the health benefits of the air-quality ***,we assessed the geographic inequality embedded in the GLE using the Gini index （GI）.Based on risk assessments of PM2.5and O3,during the first stage of CAAs（2013 to 2017）,the mean GLE was 1.87 *** of the sum of the GLE was disproportionally distributed in about one quarter of the population exposed （GI 0.44）.During the second stage of CAAs（2017 to 2020）,the mean GLE increased to 3.94 months and geographic inequality decreased （GI 0.18）.According to our assessments,CAAs were enhanced,from the first to second stages,in terms of not only preventing premature mortality but also ameliorating health *** enhancements were related to increased sensitivity to the health effects of air pollution and synergic control of PM2.5and *** findings will contribute to optimizing future CAAs.

关键词： clean air action public health inequality fine particulate matter ozone

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Reinforcement learning-based three-dimensional cooperative guidance law

Reinforcement learning-based three-dimensional cooperative g...

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

作者： Zhen Gu Zeqi Zhang Honglong Kang Jianfeng Li Keyuan Yue Shenmin Song Center for Control Theory and Guidance Technology Harbin Institute of Technology Harbin China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China

ISBN: (数字)9798350373691

ISBN: (纸本)9798350373707

An innovative three-dimensional cooperative guidance law for striking stationary target, based on proximal policy optimization (PPO), is introduced. This novel guidance law directly correlates engagement state information with the navigation ratio of proportional navigation guidance (PNG). Initially, the cooperative homing guidance problem is transformed into a Markov decision process, and the reward function incorporates considerations for the zero-effort-miss (ZEM) and the consensus error of time-to-go. Subsequently, the cooperative homing guidance problem is transposed into the framework of reinforcement learning (RL). Ultimately, the effectiveness of the cooperative homing guidance solution is validated through numerical simulations, encompassing agent model training and Monte Carlo cases.

关键词： Training Monte Carlo methods Navigation Markov decision processes Reinforcement learning Numerical simulation Robustness

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Decadal climate variability during the pre-industrial Common Era: characteristics and mechanisms

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science Bulletin 2025年第13期70卷 2190-2203页

作者： Ning, Liang Liu, Zhengyu Mann, Michael E. Liu, Jian Yan, Mi Sun, Weiyi Chen, Kefan Qin, Yanmin Wen, Qin State Key Laboratory of Climate System Prediction and Risk Management Nanjing210023 China Key Laboratory for Virtual Geographic Environment Ministry of Education Nanjing210023 China State Key Laboratory Cultivation Base of Geographical Environment Evolution and Regional Response of Jiangsu Province Nanjing210023 China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing210023 China School of Geography Nanjing Normal University Nanjing210023 China Department of Geography The Ohio State University ColumbusOH43210 United States Department of Earth and Environmental Science Annenberg School for Communication University of Pennsylvania PhiladelphiaPA19104 United States Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems School of Mathematical Science Nanjing Normal University Nanjing210023 China

In this article, we present a comprehensive review of decadal to multi-decadal climate variability during the Common Era (CE), focusing on their characteristics and mechanisms. We begin by summarizing recent advances in proxy reconstructions that reveal the paleo-evidence of decadal to multi-decadal climate variability during the CE. Decadal to multi-decadal variability has been observed in extensive sets of proxy records in the CE. Despite improvements in proxy records in the type, temporal resolution, and temporal coverage, there remains a lack of clear consistency in the preferred time scales and phases of the variability among different records. The agreements of decadal characteristics between proxy records and model simulations are higher during the periods with strong external forcings, but lower during periods of weak external forcing. We subsequently describe the recent modeling studies on the influences of external forcings and internal variability on decadal to multi-decadal climate variability with associated physical mechanisms, and some emerging research topics. Despite the improved understanding of climate variability and regional climate changes, especially over the eastern Asia summer monsoon region, several inconsistencies still exist, such as the amplitudes of responses to external forcings and relative contributions from external forcings and internal variability. The review ends with perspectives for future directions to reconcile discrepancies of decadal climate variability, such as applications of paleoclimate data assimilation and isotope-enabled transient climate modeling, and implications for projecting future decadal to multi-decadal climate changes and for improving the accuracy of decadal predictions. © 2025 science China Press

关键词： Global warming

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Design of an Ultra-Wideband Low-Profile Directional Bowtie Antenna for Ground-Penetrating Radars

Design of an Ultra-Wideband Low-Profile Directional Bowtie A...

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International Conference on Microwave and Millimeter Wave technology Proceedings

作者： Jin Wu Jing Ma Bin Shi Kun-Shan Mo Lin Peng The Key Laboratory of Microwave and Optical Wave Application Technology Guilin University of Electronic Technology Guilin Guangxi China The Science and Technology on Special System Simulation Laboratory Beijing Simulation Center Beijing China School of Electronic Information and Automation Guilin University of Aerospace Technology Guilin Guangxi China

ISBN: (数字)9798350389968

ISBN: (纸本)9798350389975

In this paper, An elliptical patch dipole antenna with resistive loading and parasitic structure is proposed. By loading the parasitic structure, the height of the antenna is reduced. The overall dimensions of the antenna are $0.16\lambda_{0}\times 0.08\lambda_{0}\times 0.03\lambda_{0}$ , and $\lambda_{0}$ is the free-space wavelength at the lowest frequency. By loading large reflective floors, the proposed antenna achieves a good unidirectional radiation performance in the whole frequency band from 0.18 GHz to 2 GHz with a $\text{VSWR} < 2$ , and an in-band peak gain of up to 7.41 dBi is obtained. It is a good candidate antenna for ground-penetrating radar.

关键词： Microwave antennas Ground penetrating radar Dipole antennas Loading Bandwidth Millimeter wave radar Radar antennas

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Study on Numerical simulation Method of Unsteady Deposition Characteristics of Particles in Surface Filtration 29

Study on Numerical Simulation Method of Unsteady Deposition ...

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2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Ma, Song Sun, Zhongning Zhou, Yanmin Gu, Haifeng Lintai Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin150001 China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin150001 China

ISBN: (纸本)9780791886502

As an important part of the ventilation system of nuclear facilities, the performance of filter is of great significance to the environment and personnel safety. With the operation of the filter, the filtration mode will change from depth filtration to surface filtration. In this paper, a numerical simulation method is developed for the unsteady deposition characteristics of particles in the surface filtration. The parcel injection model is applied to accelerate the formation and growth process of dust cake on the surface of fiber filter. A series of subroutines running in FLUENT environment are developed to enhance the capabilities of computational fluid dynamics code in ANSYS. The Brownian force is added to the DPM model to calculate the particle trajectory more accurately. The function that aerosol particles are intercepted and deposited on the surface of fiber filter to form dust cake is added. The porous media model is used to simulate the fiber filter and dust cake. The porosity and resistance coefficient change with the unsteady deposition of particles. Combined with the subroutine with FLUENT software, a numerical simulation method which can be used to predict the unsteady deposition characteristics of particles in the surface filtration is formed. The numerical simulation results are compared with the experimental results, and they are basically consistent. So the developed numerical simulation method can be used to predict the unsteady deposition characteristics of particles in the surface filtration, and can also provide a theoretical basis for the structural design of pleated filter. © 2022 by ASME.

关键词： Deposition

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Research on data assimilation strategy of turbulent separated flow over airfoil

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Applied Mathematics and Mechanics(English Edition) 2022年第4期43卷 571-586页

作者： Ying ZHANG Lin DU Weiwei ZHANG Zichen DENG National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China Complex System Dynamics and Control Academic Exchange Center School of Mathematics and StatisticsNorthwestern Polytechnical UniversityXi'an 710119China Rotor Aerodynamics Key Laboratory China Aerodynamics Research and Development CenterMianyang 621000Sichuan ProvinceChina

In order to increase the accuracy of turbulence field reconstruction,this paper combines experimental observation and numerical simulation to develop and establish a data assimilation framework,and apply it to the study of S809 low-speed and high-angle airfoil *** method is based on the ensemble transform Kalman filter(ETKF)algorithm,which improves the disturbance strategy of the ensemble members and enhances the richness of the initial members by screening high flow field sensitivity constants,increasing the constant disturbance dimensions and designing a fine disturbance *** results show that the pressure distribution on the airfoil surface after assimilation is closer to the experimental value than that of the standard Spalart-Allmaras(S-A)*** separated vortex estimated by filtering is fuller,and the eddy viscosity field information is more abundant,which is physically consistent with the observation ***,the data assimilation method based on the improved ensemble strategy can more accurately and effectively describe complex turbulence phenomena.

关键词： turbulence data assimilation ensemble disturbance strategy large angle of attack separation ensemble transform Kalman filter(ETKF)

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Mechanically Stable and Damage Resistant Freestanding Ultrathin Silver Nanowire Films with Closely Packed Crossed-Lamellar Structure

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Precision Chemistry 2024年第12期2卷 634-643页

作者： Si-Chao Zhang Huai-Ling Ga Long Zhang Yin-Bo Zhu Ya-Dong Wu Jian-Wei Liu Li-Bo Mao Mei Feng Liang Dong Zhao Pan Xiang-Sen Meng Yang Lu Shu-Hong Yu Department of Chemistry New Cornerstone Science LaboratoryInstitute of Biomimetic Materials&ChemistryAnhui Engineering Laboratory of Biomimetic MaterialsDivision of Nanomaterials&ChemistryHefei National Research Center for Physical Sciences at the MicroscaleUniversity of Science and Technology of ChinaHefei 230026China 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 ChinaHefei 230027China Anhui Key Laboratory of Controllable Chemical Reaction and Material Chemical Engineering School of Chemistry and Chemical EngineeringHefei University of TechnologyHefeiAnhui 230009P.R.China Institute of Innovative Materials(I2M) Department of ChemistryDepartment of Materials Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China

One-dimensional(1D)functional nanowires are widely used as nanoscale building blocks for assembling advanced nanodevices due to their unique ***,previous research has mainly focused on nanowire functionality,while neglecting the structural stability and damage resistance of nanowire assemblies,which are critical for the long-term operation of *** achieve excellent mechanical stability and damage resistance through sophisticated structural ***,we successfully prepared a mechanically stabilized monolamella silver nanowire(Ag NW)film,based on a facile bubblemediated assembly and nondestructive transfer strategy with the assistance of a porous mixed cellulose ester substrate,inspired by the hierarchical structure of *** to the closely packed arrangement of Ag NWs combined with their weak interfaces,the monolamellar Ag NW film can be transferred to arbitrary substrates without ***,freestanding multilamellar Ag NW films with impressive damage resistance can be obtained from the monolamellar Ag NW film,through the introduction of bioinspired closely packed crossed-lamellar(CPCL)*** CPCL structure maximizes intra-and interlamellar interactions among Ag NWs ensuring efficient stress transfer and uniform electron transport,resulting in excellent mechanical durability and stable electrical properties of the multilamellar Ag NW films.

关键词： Biomimetics hierarchical structure structural stability damage resistance functional nanowire assemblies

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