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Investigation of high rate mechanical flow followed by ignition for high-energy propellant under dynamic extrusion loading

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Defence Technology（防务技术） 2024年第2期32卷 336-347页

作者： Liying Dong Yanqing Wu Kun Yang Xiao hou State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident ***, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 22.3 MPa to 28.6 MPa, the critical value of effective plastic work required for ignition is shortened from 1280 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.

关键词： NEPE propellant Crevice extrusion Shear flow Sample thickness Ignition reaction

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Terminal attitude selection method of missile attack aircraft

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Chinese Journal of Aeronautics 2024年第2期37卷 385-400页

作者： Peng hou Yang PEI Yuxue GE Mengjie ZHU School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Research Department Shanghai Electro-Mechanical Engineering InstituteShanghai 201108China

The appropriate terminal attitude of missile is important to improve the damage effectiveness of fragmentation warhead against aircraft *** this paper,three missile terminal attitude selection methods are proposed to solve the problem of terminal attitude selection in different situations according to their respective evaluation *** MVE-based method uses the damage probability of each detonation point around the aircraft at a given attitude of missile to calculate the Mean Volume of Effectiveness(MVE)at the corresponding attitude,and then uses the MVE for different attitudes to select the terminal strike *** detonation position-based method addresses the case where the missile detonation position can be assessed in *** the effects of missile guidance errors and fuze activation position errors,Monte Carlo simulations are used to calculate the damage probability of aircraft with different strike attitudes,from which the terminal strike attitude is *** BP-ANN model-based method uses the constructed Back Propagation Artificial Neural Network(BP-ANN)model instead of simulation to calculate the evaluation indexes in the corresponding cases of MVE-based method and Detonation position-based method,which can improve the efficiency of attitude *** are conducted for different scenarios to verify the feasibility and effectiveness of the proposed method.

关键词： Aircraft vulnerability Attitude selection BP-ANN Damage probability Damage effectiveness

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Direct Conversion of Methane to Propylene

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Research 2024年第2期2023卷 463-472页

作者： Yunpeng hou Yuxiang Lan Chao Qian Shaodong Zhou College of Chemical and Biological Engineering Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture TechnologyZhejiang University310027 HangzhouP.R.China Zhejiang Provincial Innovation Center of Advanced Chemicals Technology Institute of Zhejiang University-Quzhou324000 QuzhouP.R.China

Nonoxidative coupling of methane exhibits promising prospect in that it affords value-added hydrocarbons and hydrogen with high atom ***,challenge remains in direct,selective conversion of methane to more valuable hydrocarbons like *** current work presents a catalyst with well-dispersed Ta atoms anchored by graphitic C_(3)N_(4)-supported *** a catalyst is able to convert methane selectively to ethylene and propylene at a relatively low temperature(350℃).The conception of the active center and construction of the catalyst have been described,and the origins of the catalytic performance are discussed.

关键词： methane catalyst hydrocarbons

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断层带破碎岩体采动剪切变形与渗透性演化规律

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煤田地质与勘探 2023年第8期51卷 150-160页

作者：李樯马丹张吉雄刘勇侯文涛中国矿业大学矿业工程学院江苏徐州221116 中国矿业大学深部煤炭资源开采教育部重点实验室江苏徐州221116

为探索采动影响下的断层活化突水机理,开展断层破碎岩体剪切变形与渗透性演化试验研究。基于流固耦合原理设计一套破碎岩体压剪渗流试验系统,实现破碎岩体剪切变形与渗流的耦合过程,开展多因素影响下的破碎岩体剪切-渗流耦合试验,获得... 详细信息

为探索采动影响下的断层活化突水机理,开展断层破碎岩体剪切变形与渗透性演化试验研究。基于流固耦合原理设计一套破碎岩体压剪渗流试验系统,实现破碎岩体剪切变形与渗流的耦合过程,开展多因素影响下的破碎岩体剪切-渗流耦合试验,获得连续剪切过程中颗粒级配和初始孔隙率对孔隙率和渗透性参量的影响规律。结果表明,连续剪切条件下,破碎岩体的渗透率和孔隙率变化过程大致相同,可分为3个阶段:缓慢增长阶段,破碎岩石颗粒由散乱状态向有序的组织结构调整;加速增长阶段,破碎岩石颗粒剪切膨胀;增速放缓阶段,破碎岩体颗粒的剪切变形在围压的约束下达到动态平衡。试样Talbot指数越小或初始孔隙率越大,渗透率和孔隙率敏感性越强,渗透率和孔隙率越大;非Darcy流β因子的演化规律与渗透率的演化规律相反。结合数值模拟发现,剪切作用下破碎岩体剪切带内岩石颗粒的运移是剪胀现象发生的主要原因,破碎岩体剪胀过程中颗粒的力链由随机分布向特定方向转化,表现为局部孔隙和孔喉的膨胀,是孔隙率和渗透率增加的主要原因。研究成果可为深部煤矿突水灾害机理揭示与灾害防治提供参考。

关键词：断层突水破碎岩体剪切-渗流耦合渗透特性离散元模拟

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民国武化运动的内容、逻辑及其新时代启示

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体育学研究 2022年第4期36卷 51-58页

作者：李龙侯文韬刘帅兵南京体育学院武术与艺术学院江苏南京210014 苏州大学体育学院江苏苏州215021

民国武化运动是一场针对民国危局寻找中华民族出路的运动,是相对于新文化运动而言的。其思想在今天依然具有时代价值。文章运用文献资料法、逻辑分析法等对民国武化运动的内容、逻辑及其新时代启示展开研究。研究认为,民国武化运动主要... 详细信息

民国武化运动是一场针对民国危局寻找中华民族出路的运动,是相对于新文化运动而言的。其思想在今天依然具有时代价值。文章运用文献资料法、逻辑分析法等对民国武化运动的内容、逻辑及其新时代启示展开研究。研究认为,民国武化运动主要通过改造军人群体、提倡军事教育和体育救国及武术救国等内容,培育和弘扬中华民族尚武精神。救亡图存是其应激性反应的外在逻辑,强种强国是其内在的正向逻辑。其弘扬体育和武术的内在逻辑就是强国必要强种,强种必要习武,习武必要塑造具有尚武精神的现代化人格。这些逻辑思想光芒在新时代的重要价值是加强武化教育,建设一支具有尚武精神的现代化军队;通过武化教育,培养新时代青年自强不息、敢于担当的精神品质;增强价值认同,弘扬体育和武术文化的强身健体和教育功能。

关键词：民国武化运动体育救国救亡图存强种强国尚武精神

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高频即时磁刺激对神经兴奋性与电压门控钠钾离子通道的影响

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电工技术学报 2021年第18期36卷 3787-3798页

作者：朱海军尹晓楠丁冲侯文涛徐桂芝省部共建电工装备可靠性与智能化国家重点实验室(河北工业大学) 天津300130 河北工业大学天津市生物电工与智能健康重点实验室天津300130

经颅磁刺激作为一种无创的脑刺激技术,因其在神经调控方面的良好效果,已广泛应用于科学研究与临床应用。该文旨在研究不同强度的即时磁刺激对神经兴奋性与电压门控钠离子通道及电压门控钾离子通道的影响。对急性小鼠大脑切片施加0T、0.3... 详细信息

经颅磁刺激作为一种无创的脑刺激技术,因其在神经调控方面的良好效果,已广泛应用于科学研究与临床应用。该文旨在研究不同强度的即时磁刺激对神经兴奋性与电压门控钠离子通道及电压门控钾离子通道的影响。对急性小鼠大脑切片施加0T、0.3T、0.5T的高频即时磁刺激,采用全细胞膜片钳技术记录海马齿状回颗粒神经元的静息电位与诱发神经放电,以及电压门控钠通道、瞬时外向钾通道、延迟整流钾通道在激活、失活、恢复等不同过程中的通道电流。结果表明,磁刺激可以改变相关离子通道的动力学特性来激活钠电流抑制钾电流,进而提高神经兴奋性,且磁刺激的这种神经调控作用具有强度依赖性。

关键词：磁刺激神经兴奋性电压门控钠电流瞬时外向钾电流延迟整流钾电流

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Dual Frequency Transformer for Efficient SDR-to-HDR Translation

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Machine Intelligence Research 2024年第3期21卷 538-548页

作者： Gang Xu Qibin hou Ming-Ming Cheng Tianjin Media Computing Center College of Computer ScienceNankai UniversityTianjin300000China

The SDR-to-HDR translation technique can convert the abundant standard-dynamic-range (SDR) media resources to high-dynamic-range (HDR) ones, which can represent high-contrast scenes, providing more realistic visual experiences. While recent vision Transformers have achieved promising performance in many low-level vision tasks, there are few works attempting to leverage Transformers for SDR-to-HDR translation. In this paper, we are among the first to investigate the performance of Transformers for SDR-to-HDR translation. We find that directly using the self-attention mechanism may involve artifacts in the results due to the inappropriate way to model long-range dependencies between the low-frequency and high-frequency components. Taking this into account, we advance the self-attention mechanism and present a dual frequency attention (DFA), which leverages the self-attention mechanism to separately encode the low-frequency structural information and high-frequency detail information. Based on the proposed DFA, we further design a multi-scale feature fusion network, named dual frequency Transformer (DFT), for efficient SDR-to-HDR translation. Extensive experiments on the HDRTV1K dataset demonstrate that our DFT can achieve better quantitative and qualitative performance than the recent state-of-the-art methods. The code of our DFT is made publicly available at https://***/CS-GangXu/DFT.

关键词： Standard-dynamic-range to high-dynamic-range(SDR-to-HDR)translation Transformer dual frequency attention(DFA) frequency-aware feature decomposition efficient model

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Robust Forecasting-Aided State Estimation Considering Uncertainty in Distribution System

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1632-1641页

作者： Dongchen hou Yonghui Sun Linchuang Zhang Sen Wang College of Energy and Electrical Engineering Hohai UniversityNanjing 210098China

With the development of the smart grid,the distribution system operation conditions become more complex and ***,due to the influence of observation outliers and uncertain noise statistics,it is more difficult to grasp the dynamic operation characteristics of distribution *** order to address these problems,by using projection statistics and the noise covariance updating technology based on the Sage-Husa noise estimator,for distribution power system with outliers and uncertain noise statistics,a robust adaptive cubature Kalman filter forecasting-aided state estimation method is proposed based on generalized-maximum likelihood type ***,an adaptive strategy,which can enhance the filtering accuracy under normal conditions,is *** the simulation part,the branch parameters and node load parameters of the test system are appropriately modified to simulate the asymmetry of the three-phase branch parameters and the asymmetry of the three-phase ***,through simulation experiments on the improved test system,it is verified that the robust forecasting-aided state estimation method,presented in this paper,can effectively perceive the actual operating state of the distribution network in different simulation scenarios.

关键词： Cubature Kalman filter distribution power system forecasting-aided state estimation projection statistics

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Hierarchical vectorization for facial images

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Computational Visual Media 2024年第1期10卷 97-118页

作者： Qian Fu Linlin Liu Fei hou Ying He School of Computer Science and Engineering Nanyang Technological University639798SingaporeSingapore Data61 Commonwealth Scientific and Industrial Research OrganisationSydney2015Australia Interdisciplinary Graduate School Nanyang Technological University and Alibaba Group639798SingaporeSingapore State Key Laboratory of Computer Science Institute of SoftwareChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China

The explosive growth of social media means portrait editing and retouching are in high *** portraits are commonly captured and stored as raster images,editing raster images is non-trivial and requires the user to be highly *** at developing intuitive and easy-to-use portrait editing tools,we propose a novel vectorization method that can automatically convert raster images into a 3-tier hierarchical *** base layer consists of a set of sparse diffusion curves(DCs)which characterize salient geometric features and low-frequency colors,providing a means for semantic color transfer and facial expression *** middle level encodes specular highlights and shadows as large,editable Poisson regions(PRs)and allows the user to directly adjust illumination by tuning the strength and changing the shapes of *** top level contains two types of pixel-sized PRs for high-frequency residuals and fine details such as pimples and *** train a deep generative model that can produce high-frequency residuals *** to the inherent meaning in vector primitives,editing portraits becomes easy and *** particular,our method supports color transfer,facial expression editing,highlight and shadow editing,and automatic *** quantitatively evaluate the results,we extend the commonly used FLIP metric(which measures color and feature differences between two images)to consider *** new metric,illumination-sensitive FLIP,can effectively capture salient changes in color transfer results,and is more consistent with human perception than FLIP and other quality measures for portrait *** evaluate our method on the FFHQR dataset and show it to be effective for common portrait editing tasks,such as retouching,light editing,color transfer,and expression editing.

关键词： face editing vectorization Poisson editing color transfer illumination editing expression editing

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Characteristics of the HIV/AIDS Epidemic among People Aged≥50 Years in China during 2018–2021

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Biomedical and Environmental Sciences 2024年第4期37卷 399-405页

作者： hou Yu Shan JIN Yi Chen CAI Chang TANG hou Lin QIN Qian Qian LYU Fan National Center for AIDS/STD Control and Prevention Chinese Center for Disease Control and PreventionBeijing 102206China

Objective This study aimed to determine the current epidemiological status of PLWHA aged≥50 years in China from 2018 to *** also aimed to recommend targeted interventions for the prevention and treatment of HIV/AIDS in elderly *** Data on newly reported cases of PLWHA,aged≥50 years in China from 2018 to 2021,were collected using the *** tests and spatial analyses were also *** Between 2018 and 2021,237,724 HIV/AIDS cases were reported among patients aged≥50 years in *** main transmission route was heterosexual transmission(91.24%).Commercial heterosexual transmission(CHC)was the primary mode of transmission among males,while non-marital non-CHC([NMNCHC];60.59%)was the prevalent route in *** proportion of patients with CHC decreased over time(Z=67.716,P<0.01),while that of patients with NMNCHC increased(Z=153.05,P<0.01).The sex ratio varied among the different modes of infection,and it peaked at 17.65 for *** spatial analysis indicated spatial clustering,and the high-high clustering areas were mainly distributed in the southwestern and central-southern *** In China,PLWHA,aged≥50 years,were predominantly infected through heterosexual *** primary modes of infection were CHC and *** were variations in the sex ratio among different age groups,infected through various sexual ***/AIDS cases exhibited spatial *** on these results,the expansion of HIV testing,treatment,and integrated behavioral interventions in high-risk populations is recommended to enhance disease detection in key regions.

关键词： HIV/AIDS Aged≥50 years China

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