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Prediction of solar activities:Sunspot numbers and solar magnetic synoptic maps

Science China Earth Sciences 2024年第8期67卷 2460-2477页

作者： Rui ZHUO Jiansen HE Die DUAN Rong LIN Ziqi WU Limei YAN Yong WEI School of Earth and Space Sciences Peking UniversityBeijing 100091China College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Centre for Mathematical Plasma Astrophysics Department of MathematicsKU LeuvenLeuven 3001Belgium Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

The evolution of solar magnetic fields is significant for understanding and predicting solar *** our knowledge of solar magnetic fields largely depends on the photospheric magnetic *** this paper,based on the spherical harmonic expansion of the photospheric magnetic field observed by Wilcox Solar Observatory,we analyze the time series of spherical harmonic coefficients and predict Sunspot Number as well as synoptic maps for Solar Cycle *** find that solar maximum years have complex short-period disturbances,and the time series of coefficient g_(7)~0 is nearly in-phase with Sunspot Number,which may be related to solar meridional *** Long Short-Term Memory networks(LSTM),our prediction suggests that the maximum of Solar Cycle 25 is likely to occur in June 2024 with an error of 8 months,the peak sunspot number may be 166.9±22.6,and the next solar minimum may occur around January *** incorporating Empirical Mode Decomposition,we enhance our forecast of synoptic maps truncated to Order 5,validating their relative *** prediction not only addresses a gap in forecasting the global distribution of the solar magnetic field but also holds potential reference value for forthcoming solar observation plans.

关键词： Solar activity prediction Solar magnetic field Spherical harmonic expansion Long-Short Term Memory(LSTM) Empirical Mode Decomposition(EMD)

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An improved four-dimensional variation source term inversion model with observation error regularization

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Defence Technology（防务技术） 2023年第6期24卷 349-360页

作者： Chao-shuai Han Xue-zheng Zhu Jin Gu Guo-hui Yan Xiao-hui Gao Qin-wen Zuo institute of nbc Defence BeijingChina State Key Laboratory of nbc Protection for Civilian BeijingChina

Aiming at the Four-Dimensional Variation source term inversion algorithm proposed earlier,the observation error regularization factor is introduced to improve the prediction accuracy of the diffusion model,and an improved Four-Dimensional Variation source term inversion algorithm with observation error regularization(OER-4DVAR STI model)is ***,by constructing the inversion process and basic model of OER-4DVAR STI model,its basic principle and logical structure are ***,the observation error regularization factor estimation method based on Bayesian optimization is proposed,and the error factor is separated and optimized by two parameters:error statistical time and deviation ***,the scientific,feasible and advanced nature of the OER-4DVAR STI model are verified by numerical simulation and tracer test *** experimental results show that OER-4DVAR STI model can better reverse calculate the hazard source term information under the conditions of high atmospheric stability and flat underlying *** with the previous inversion algorithm,the source intensity estimation accuracy of OER-4DVAR STI model is improved by about 46.97%,and the source location estimation accuracy is improved by about 26.72%.

关键词： Source term inversion Four dimensional variation Observation error regularization factor Bayesian optimization SF6 tracer test

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Character of Convective Systems Producing Short-Term Heavy Precipitation in Central China Revealed by Kilometer and Minute Interval Observations

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Journal of Meteorological Research 2024年第3期38卷 530-541页

作者： Zitong CHEN Yunying LI Zhiwei ZHANG Jing SUN Chengzhi YE Anyuan XIONG College of Meteorology and Oceanography National University of Defense TechnologyChangsha410073China High Impact Weather Key Laboratory of China Meteorological Administration Changsha410073China Unit No.92192 of Chinese People’s Liberation Army Ningbo315000China Hubei Key Research Laboratory for Heavy Rain Monitoring and Warning Institute of Heavy RainChina Meteorological AdministrationWuhan430223China institute of Meteorological Sciences of Hunan Province Hunan Meteorological BureauChangsha410118China National Meteorological Information Centre China Meteorological AdministrationBeijing100081China

Accurate forecasting of heavy precipitation in central China is still a challenge,within which a key issue is our still incomplete understanding of the convective systems(CSs)responsible for such *** this study,through use of an iterative rain-cell tracking algorithm,the macroscale characteristics(scale,intensity,duration,etc.)of the CSs that produced 595 short-term heavy precipitation events in Hunan Province,central China,are quantitatively analyzed,based on radar reflectivity,echo top,and rainfall observations at 1-km and 6-min intervals in April-September of *** results show that CSs present significant seasonal and diurnal *** CSs usually cover a larger echo area with stronger convective cores and thus generate more precipitation than summer CSs,though summer CSs develop more vigorously and *** initiated at 1400-1600 local time are characterized by the strongest convection and a smaller spatiotemporal scale,causing violent and transient showers with typical areal precipitation of 0.5-1 mm km^(−2),but less total *** analyses of the relationships among the scale,intensity,duration,and total precipitation of CSs reveal that the convective intensity is linearly correlated to the spatiotemporal scale of CSs,with the duration increasing on average by 0.0372 h dBZ^(−1);the echo area is significantly correlated to the total precipitation,and the duration and rainfall amount are connected with the area expansion rate(AER)of CSs:when the AER exceeds 50%,CSs expand rapidly with increasing total precipitation,but the duration is *** findings provide a helpful reference for the forecasting of short-term heavy precipitation induced by CSs in central China.

关键词： convective system radar reflectivity factor total precipitation iterative rain-cell tracking

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Ozone kinetics of dimethyl sulfide in the presence o water vapor

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Frontiers of Environmental Science & Engineering 2013年第6期7卷 833-835页

作者： Haitao WANG Chemical defense Research institute of Beijing Beijing 102205 China State Key Laboratory of nbc Protection for Civilian Beijing 102205 China

The outdoor smog chamber was used to thorough investigate the rate constants of gas-phase reaction between dimethyl sulfide （DMS） and ozone （O3） under conditions of relative humidity 55.0%-67.8% at （296±2）K for the first time. The rate constants were measured, at a total pressure of 1 atm, to be （10.4±0.2） × 10^-19 cm^3·molecule^-1·s^-1 at relative humidity of 67.5%±0.3% at 298K, （10.1±0.1） × 10^-19cm^3·molecule^-1·s^-1 at relative humidity of 66.5%±0.5% at 296K, （7.75±0.39） × 10^-19cm^3·molecule^-1·s^-1 at relative humidity of 64.8%± 0.1% at 294K and （3.42±0.21） × 10^-19cm^3·molecu- le^-1·s^-1at relative humidity of 55.8%±0.8% at 295K. Base on these results, it is possible to see the reaction of O3/ DMS in the presence of water vapor as an important sink for DMS in the earth atmosphere.

关键词： rate constants ozone (03) dimethyl sulfide(DMS) water vapor

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Applications of magnetic nanoparticles in surface-enhanced Raman scattering(SERS)detection of environmental pollutants

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Journal of Environmental Sciences 2019年第6期31卷 14-34页

作者： Dan Song Rong Yang Feng Long Anna Zhu School of Environment and Natural Resources Renmin University of China Research institute of Chemical defense Academy of Military Sciences PLA China State Key Laboratory of nbc Protection FOR Civilian

Environmental pollution, a major problem worldwide, poses considerable threat to human health and ecological environment. Efficient and reliable detection technologies, which focus on the appearance of emerging environmental and trace pollutants, are urgently needed. Surface-enhanced Raman scattering(SERS) has become an attractive analytical tool for sensing trace targets in environmental field because of its inherent molecular fingerprint specificity and high sensitivity. In this review, we focused on the recent developments in the integration of magnetic nanoparticles(MNPs) with SERS for facilitating sensitive detection of environmental pollutants. An overview and classification of different types of MNPs for SERS detection were initially provided, enabling us to categorize the huge amount of literature that was available in the interdisciplinary research field of MNPs based SERS technology. Then, the basic working principles and applications of MNPs in SERS detection were presented. Subsequently, the detection technologies integrating MNPs with SERS that eventually were used for the detection of various environmental pollutions were reviewed. Finally, the advantages of MNP-basedSERS detection technology for environmental pollutants were concluded, and the current challenges and future outlook of this technology in practical applications were highlighted. The application of the MNPsbasedSERS techniques for environmental analysis will be significantly advanced with the great progresses of the nanotechnologies, optics, and materials.

关键词： Magnetic nanoparticles Surface-enhanced Raman scattering SERS substrates Environmental pollutant detection

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Uncertainty-Aware Physical Simulation of Neural Radiance Fields for Fluids

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 1143-1163页

作者： Haojie Lian Jiaqi Wang Leilei Chen Shengze Li Ruochen Cao Qingyuan Hu Peiyun Zhao Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education Taiyuan University of TechnologyTaiyuan030024China Henan International Joint Laboratory of Structural Mechanics and Computational Simulation College of Architectural and Civil EngineeringHuanghuai UniversityZhumadian463000China National Innovation institute of defense Technology Academy of Military ScienceBeijing100091China School of Software Taiyuan University of TechnologyJinzhong030600China School of Science Jiangnan UniversityWuxi214122China

This paper presents a novel framework aimed at quantifying uncertainties associated with the 3D reconstruction of smoke *** approach reconstructs color and density fields from 2D images using Neural Radiance Field(NeRF)and improves image quality using frequency *** NeRF model is obtained via joint training ofmultiple artificial neural networks,whereby the expectation and standard deviation of density fields and RGB values can be evaluated for each *** addition,customized physics-informed neural network(PINN)with residual blocks and two-layer activation functions are utilized to input the density fields of the NeRF into Navier-Stokes equations and convection-diffusion equations to reconstruct the velocity *** velocity uncertainties are also evaluated through ensemble *** effectiveness of the proposed algorithm is demonstrated through numerical *** presentmethod is an important step towards downstream tasks such as reliability analysis and robust optimization in engineering design.

关键词： Uncertainty quantification neural radiance field physics-informed neural network frequency regularization twolayer activation function ensemble learning

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Challenges and modification strategies of high-voltage cathode materials for Li-ion batteries

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Chinese Journal of Structural Chemistry 2023年第10期42卷 67-79页

作者： Yue Wang Caixia Xu Xingtao Tian Siyu Wang Yan Zhao institute of nbc defense PLA ArmyBeijing102205China School of Energy and Power Engineering Jiangsu UniversityZhenjiang212013China

Li-ion batteries(LIBs)have gained wide recognition as effective energy storage devices and power supply sources due to their exceptional volumetric energy density,mass energy density and cycling *** cathode materials,a key component of LIBs,play a crucial role in determining the electrochemical performance of these ***,there is an increasing demand to explore and investigate suitable high-energy electrode materials that can provide greater capacity and output voltage for the next generation of *** paper aims to provide a comprehensive overview of the latest researches on five typical high-voltage cathode ***,this review will focus on the detailed analysis of their crystalline structures,reaction mechanisms during cycling,current research status and strategies aimed at improving or enhancing their overall electrochemical ***,the insights presented in this review will help researchers design and develop high-energy cathode materials with improved performance for the next generation of LIBs.

关键词： Research advances Li-ion batteries Lithium iron phosphate Layered cathode Lithium-rich oxides Lithium manganate

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节流式燃氧分离固体发动机准一维内弹道数值研究

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Acta Mechanica Sinica 2024年第1期40卷 85-101页

作者：王立民王富祺王志邦王英男王革关奔周星 College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China Inner Mongolia Dynamic and Mechanical institute Hohhot 010011China College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbin 150001China College of Engineering Peking UniversityBeijing 100871China

本文建立了用于计算节流式燃氧分离固体发动机内弹道的准一维数值模型。节流式燃氧分离固体发动机通过改变富燃燃烧室和富氧燃烧室之间的节流阀开口半径来实现其推力的调节。数值模型采用简化的反应机理来描述化学非平衡过程,且考虑了... 详细信息

本文建立了用于计算节流式燃氧分离固体发动机内弹道的准一维数值模型。节流式燃氧分离固体发动机通过改变富燃燃烧室和富氧燃烧室之间的节流阀开口半径来实现其推力的调节。数值模型采用简化的反应机理来描述化学非平衡过程,且考虑了燃烧室中的质量添加、壁面摩擦和推进剂燃面退移过程。利用该数值模型展示了节流式燃氧分离固体发动机的内部流动参数分布和工作性能.发动机稳定工作状态结果显示,当节流阀开度半径由10.5mm调节至1.4mm时,发动机推力由121.82N增加至250.60N,推力提升了206%,验证了节流式燃氧分离固体发动机概念的可行性.流动参数也表明节流阀的调节作用仅在阀门开度较小时才得以充分体现.发动机动态工作过程结果显示,在调节阀停止作动时,节流式燃氧分离固体发动机性能会产生负调现象,因而需要对发动机采取额外的保护措施.对节流式燃氧分离固体发动机调节能力的理论预测发现,发动机的推力调节能力受限于富燃燃烧室压力和初始质量流量比,需要在多个参数之间进行权衡以实现合理的推力调节比.最后对推进剂的布置方式进行了初步探讨结果表明,燃氧推进剂布置下发动机的推力调节能力优于氧燃推进剂布置。

关键词：固体发动机化学非平衡燃烧室压力阀门开度质量流量比流动参数节流阀开度准一维

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Local Adaptive Gradient Variance Attack for Deep Fake Fingerprint Detection

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Computers, Materials & Continua 2024年第1期78卷 899-914页

作者： Chengsheng Yuan Baojie Cui Zhili Zhou Xinting Li Qingming Jonathan Wu Engineering Research Center of Digital Forensics Ministry of EducationNanjing University of Information Science and TechnologyNanjing210044China School of Computer Science Nanjing University of Information Science and TechnologyNanjing210044China institute of Artificial Intelligence and Blockchain Guangzhou UniversityGuangzhou510006China School of International Relations National University of Defense TechnologyNanjing210039China Department of Electrical and Computer Engineering University of WindsorWindsorN9B 3P4Canada

In recent years,deep learning has been the mainstream technology for fingerprint liveness detection(FLD)tasks because of its remarkable ***,recent studies have shown that these deep fake fingerprint detection(DFFD)models are not resistant to attacks by adversarial examples,which are generated by the introduction of subtle perturbations in the fingerprint image,allowing the model to make fake *** of the existing adversarial example generation methods are based on gradient optimization,which is easy to fall into local optimal,resulting in poor transferability of adversarial *** addition,the perturbation added to the blank area of the fingerprint image is easily perceived by the human eye,leading to poor visual *** response to the above challenges,this paper proposes a novel adversarial attack method based on local adaptive gradient variance for *** ridge texture area within the fingerprint image has been identified and designated as the region for perturbation ***,the images are fed into the targeted white-box model,and the gradient direction is optimized to compute gradient ***,an adaptive parameter search method is proposed using stochastic gradient ascent to explore the parameter values during adversarial example generation,aiming to maximize adversarial attack *** results on two publicly available fingerprint datasets show that ourmethod achieves higher attack transferability and robustness than existing methods,and the perturbation is harder to perceive.

关键词： FLD adversarial attacks adversarial examples gradient optimization transferability

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Research progress of integrated optical gyroscope

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Chinese Optics Letters 2024年第3期22卷 42-49页

作者：郭宏杰刘海锋雷明谭满清宋志刚 institute of Semiconductors Chinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-electronics Technology University of Chinese Academy of SciencesBeijing 100049China Beijing Huairou Instruments and Sensors Co. Ltd.Beijing 101400China Beijing institute of Automation and Control Equipment Key Laboratory of National Defense Science and Technology of Inertial TechnologyBeijing 100074China

Integrated optical gyroscopes(IOGs)have been an efficient tool for numerous applications in various fields,including inertial navigation,flight control,and earthquake ***,we review the progress of integrated optical gyroscopes based on two categories of integrated interferometric optical gyroscopes(IIOGs)and integrated resonant optical gyroscopes(IROGs).

关键词： integrated optical gyroscopes interferometric optical gyroscopes integrated resonant optical gyroscopes

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