检索结果-南通市图书馆

(DarkAI)Mapping the large-scale density field of dark matter using artificial intelligence

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 143-159页

作者： Zitong Wang Feng Shi Xiaohu Yang Qingyang Li yanming Liu Xiaoping Li School of Aerospace Science and Technology Xidian UniversityXi’an 710126China Department of Astronomy School of Physics and Astronomyand Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute and Key Laboratory for Particle Physics Astrophysics and CosmologyMinistry of EducationShanghai Jiao Tong UniversityShanghai 200240China Institute for Astronomy University of EdinburghRoyal ObservatoryEdinburgh EH93HJUnited Kingdom

Herein,we present a deep-learning technique for reconstructing the dark-matter density field from the redshift-space distribution of dark-matter *** built a UNet-architecture neural network and trained it using the COmoving Lagrangian Acceleration fast simulation,which is an approximation of the N-body simulation with 5123 particles in a box size of 500 h^(-1)***,we tested the resulting UNet model not only with training-like test samples but also with standard N-body simulations,such as the Jiutian simulation with 61443particles in a box size of 1000 h^(-1)Mpc and the ELUCID simulation,which has a different *** real-space dark-matter density fields in the three simulations can be reconstructed reliably with only a small reduction of the cross-correlation power spectrum at 1%and 10%levels at k=0.1 and 0.3 h Mpc-1,*** reconstruction clearly helps to correct for redshift-space distortions and is unaffected by the different cosmologies between the training(Planck2018)and test samples(WMAP5).Furthermore,we tested the application of the UNet-reconstructed density field to obtain the velocity&tidal field and found that this approach provides better results compared with the traditional approach based on the linear bias model,showing a 12.2%improvement in the correlation slope and a 21.1%reduction in the scatter between the predicted and true ***,our method is highly efficient and has excellent extrapolation reliability beyond the training *** provides an ideal solution for determining the three-dimensional underlying density field from the plentiful galaxy survey data.

关键词： dark matter large-scale structure cosmology

Exciting broadband thermochromic transmission property opposite to vanadium dioxide in the atmospheric window

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第7期67卷 2244-2254页

作者： GONG YiQuan GUO yanming CHEN ShuNi LI Meng PAN QingHui SHUAI Yong Ministry of Industry and Information Technology Key Laboratory of Aerospace Thermophysics School of Energy Science and EngineeringHarbin Institute of TechnologyHarbin 150001China

The traditional telecommunications band performs poorly in harsh weather conditions due to atmospheric absorption. In recent years, researchers have begun to study optical communication through atmospheric windows, and optical switches are an essential component of optical communication. A broadband atmospheric window optical switch was proposed based on Vanadium dioxide and magnetic polaritons(MP). It is formed by the stacking of two metal-dielectric-metal structures. The simulation results show that the modulation depth can reach 98.38%, and the extinction ratio is 17.93 dB. By calculating the magnetic field, we confirmed that the reason for the “off” mode is the coupling between the different MP modes, while the “on”mode is the excitation of MP. The optical switch we proposed may be applied to radiation cooling and optical satellite communication.

关键词： optical communication thermochromic property atmospheric window optical switch magnetic polariton

同方期刊数据库

A Deep Learning Approach to Shape Optimization Problems for Flexoelectric Materials Using the Isogeometric Finite Element Method

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第5期139卷 1935-1960页

作者： Yu Cheng Yajun Huang Shuai Li Zhongbin Zhou Xiaohui Yuan yanming Xu College of Architecture and Civil Engineering Xinyang Normal UniversityXinyang464000China Henan Unsaturated Soil and Special Soil Engineering Technology Research Center Xinyang Normal UniversityXinyang464000China College of Intelligent Construction Wuchang University of TechnologyWuhan430223China College of Civil Engineering and Architecture Dalian UniversityDalian116622China Henan International Joint Laboratory of Structural Mechanics and Computational Simulation School of Architecture and Civil EngineeringHuanghuai UniversityZhumadian463000China

A new approach for flexoelectricmaterial shape optimization is proposed in this *** this work,a proxymodel based on artificial neural network(ANN)is used to solve the parameter optimization and shape optimization *** improve the fitting ability of the neural network,we use the idea of pre-training to determine the structure of the neural network and combine different optimizers for *** isogeometric analysis-finite element method(IGA-FEM)is used to discretize the flexural theoretical formulas and obtain samples,which helps ANN to build a proxy model from the model shape to the target *** effectiveness of the proposed method is verified through two numerical examples of parameter optimization and one numerical example of shape optimization.

关键词： Shape optimization deep learning flexoelectric structure finite element method isogeometric

Space/Air Covert Communications:Potentials,Scenarios,and Key Technologies

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Communications 2024年第3期21卷 1-18页

作者： Mao Haobin Liu yanming Zhu Lipeng Mao Tianqi Xiao Zhenyu Zhang Rui Han Zhu Xia Xianggen School of Electronic and Information Engineering Beihang UniversityBeijing 100191China Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore School of Science and Engineering Shenzhen Research Institute of Big Datathe Chinese University of Hong KongShenzhenGuangdong 518172China Department of Electrical and Computer Engineering University of HoustonHoustonTX 77004USA Department of Computer Science and Engineering Kyung Hee UniversitySeoulSouth Korea446-701 Department of Electrical and Computer Engineering University of DelawareNewarkDE 19716USA

Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wireless propagation environment and the broad coverage pose severe threats to the protection of private data. Emerging covert communications provides a promising solution to achieve robust communication security. Aiming at facilitating the practical implementation of covert communications in space/air networks, we present a tutorial overview of its potentials, scenarios, and key technologies. Specifically, first, the commonly used covertness constraint model, covert performance metrics, and potential application scenarios are briefly introduced. Then, several efficient methods that introduce uncertainty into the covert system are thoroughly summarized, followed by several critical enabling technologies, including joint resource allocation and deployment/trajectory design, multi-antenna and beamforming techniques, reconfigurable intelligent surface(RIS), and artificial intelligence algorithms. Finally, we highlight some open issues for future investigation.

关键词： artificial intelligence(AI) sixth generation(6G) space-air-ground integrated networks(SAGINs) space/air covert communications

Electrical control of excitonic oscillator strength and spatial distribution in a monolayer semiconductor

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第9期17卷 8424-8430页

作者： yanming Wang Junrong Zhang Tianhua Ren Meng Xia Long Fang Xiangyi Wang Xingwang Zhang Kai Zhang Junyong Wang School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026China CAS Key Laboratory of Nanophotonic Materials and Devices&Key Laboratory of Nanodevices and Applications i-LabSuzhou Institute of Nano-Tech and Nano-Bionics(SINANO)Chinese Academy of SciencesSuzhou 215123China Institute of Applied Physics and Materials Engineering University of MacaoTaipaMacao 999078China College of New Energy Inner Mongolia University of TechnologyHohhot 010051China

Electrical modulation of luminescence is significant to modern light-emitting *** transition metal dichalcogenides are emerging direct-bandgap luminescent materials with unique excitonic properties,and the multiple exciton complexes provide new opportunities to modulate the property of luminescence in atomically thin ***,we report an electrical control of exciton emission in the oscillator strength and spatial distribution of excitons in a monolayer *** modulation of excitonic emission intensity with a degree of modulation of~92%has been demonstrated by an electric field at room *** spatial carrier redistribution tuned by a lateral electric field results in distinct excitonic emission patterns by *** modulation approach to exciton oscillator strength and distribution provides an efficient way to investigate the exciton diffusion dynamics and to construct electrically tunable optoelectronic devices.

关键词： monolayer semiconductor exciton electrical modulation spatial distribution

Comparing the effects of dual-task training and single-task training on walking,balance and cognitive functions in individuals with Parkinson’s disease:A systematic review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Medical Journal 2024年第13期137卷 1535-1543页

作者： Xiaoying Lin yanming Zhang Xiaowei Zhang Xi Chen Jianhua Liu Lei Yang Marco Yiu Chung Pang Department of Rehabilitation Medicine the First Affiliated Hospital of Xi’an Jiaotong UniversityXi’anShaanxi 710061China Department of Rehabilitation Medicine The Second People’s Hospital of KunmingKunmingYunnan 650051China Department of Rehabilitation Medicine Xuanwu HospitalCapital Medical UniversityBeijing 100000China Department of Physical Therapy China Rehabilitation Research CenterBeijing 100000China Department of Rehabilitation Sciences The Hong Kong Polytechnic UniversityHong Kong 999077China

Background:This systematic review aimed to examine whether dual-task(DT)training was superior to single-task(ST)training in improving DT walking,balance and cognitive functions for individuals with Parkinson’s disease(PD).Methods:Literature search was performed in the following electronic databases:PubMed,the Cochrane Library,Web of Science,and Metstr covering inception to May 10,*** in order to facilitate comparison across trials,we calculated the effect size(Hedges’g)of gait,balance,cognitive,and other parameters under both ST and DT conditions,using the mean change score and standard deviation(SD)of change score of the experimental and control *** controlled trials that examined the effects of DT motor and cognitive training in individuals with Parkinson’s disease were included for this systematic ***:A total of 214 participants recruited from six articles(actually five trials)were involved in this *** terms of walking ability,only double support time and stride time variability showed significant between-group difference(Hedges’g=0.34,0.18,respectively).Compared to ST training group,DT training group had a more improvement effect in laboratory balance measurement(Hedges’g=0.18,1.25),but no significant improvement in clinical balance *** significant between-group differences were observed,thus its training effect on cognitive function was ***:The DT training failed to achieve promising results better than ST training in improving DT walking and balance functions for individuals with *** firm conclusion cannot be drawn at present,due to the limited number of eligible *** sample size and high-quality studies are needed to investigate the effectiveness of DT training in individuals with PD.

关键词： Parkinson’s disease Dual-task training Mobility Cognition Systematic review

Transpiration Rates of Carex Meyeriana in Relation to Micrometerological Factors in a Mountain Valley Wetland

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2009年第3期6卷 293-298页

作者： XU Huifeng JIN yanming deng Wei XU Kezhang WANG Zhen College of Agriculture Jilin Agricultural University Changchun 130008 P.R. China. Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610042 P.R. China. University of Nebraska-Board of Regents Lincoln NE 68503-1435 USA

In order to reveal transpiration rates of wetland plants and its relationships to micro-meterological factors in a mountain valley wetland, relative humidity, air temperature, leaf temperature, soil temperature, photo flux density and transpiration rates were measured once two hours in a Carex meyeriana wetland of the Changbai Mountain valley in dry (July) and wet (September) of 2003, respectively. Results showed that the tendency of "decreasing after increasing" was obvious in wet season. However, a relatively stable trend was observed for the transpiration in dry season.. Generally, the photon flux density of Carex meyeriana was higher in wet season than that in dry season. However, the variabilities of leaf temperature, air temperature and relative humidity were similar in both seasons. Higher transpiration rates of Carex meyeriana leaves were observed in July (varied from 40 to 150 mol·m-2·s-1) compared to those (varied from 7 to 14 mol·m-2·s-1) in September. Transpiration rates were significantly correlated with air temperature (P<0.01), leaf temperature (P<0.01), and wind speed (P<0.05), but correlationship between relative humidity and photo flux density was not significant (P<0.05).

关键词：叶片蒸腾速率乌拉苔草湿地植物山谷相对湿度空气温度通量密度叶片温度

Analysis on characteristics of extreme precipitation indices and atmospheric circulation in Northern Shanxi

在线全文

学校读者我要写书评

暂无评论

Research in Cold and Arid Regions 2024年第2期16卷 84-97页

作者： Xia Cai Yan Song Lin Cai Xin Su GuiHua Liang yanming Xu Shuozhou Meteorological Bureau of Shanxi Province ShuozhouShanxi 036002China China Meteorological Administration Training Center Beijing 100081China Heze University of Shandong Province HezeShandong 274000China Huafeng Meteorological Media Group Beijing 100081China Shuocheng Meteorological Bureau ShuozhouShanxi 036002China

This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020,and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average reanalysis *** study employs techniques such as empirical orthogonal function(EOF)decomposition,MannKendall mutation and other methods to investigate the spatiotemporal distribution of extreme precipitation index in northern Shanxi and their correlation with atmospheric *** research results show that:the absolute index,relative index,intensity index and sustained dry period index(CDD)in the continuous index appear from southwest to *** spatial distribution characteristics of the central region decrease,while the continuous wet period(CWD)decreases from the central to the east and *** three indices Rx1day,Rx5day,and CWD mutated in 1978,1975,and 1983 respectively,and other extreme precipitation indices all appeared in a sudden change from a low-value period to a high-value period occurred around *** the high-value years of the summer extreme precipitation index,there is a significant negative anomaly in the height field in the mid-high latitude regions of *** Shanxi is controlled by a broad low-pressure trough in the Lake Baikal *** vapor transported via the east,west,and south routes converges in the northern Shanxi region and encounters cold air from the *** is a strong upward motion anomaly at 500 hPa in the troposphere,and the dynamic conditions of upper-level divergence and lower-level convergence lead to more summer extreme precipitation in the northern Shanxi ***,in the low-value years of the summer extreme precipitation index,northern Shanxi is affected by a strong high-pressure ridge north of Lake *** is a downward motion anomaly at 500 hPa,and the northern Shanxi region lacks water *** cold and warm air cannot converge,and both the water vapor conditions

关键词： Northern Shanxi Extreme precipitation indices Spatio-temporal distribution and evolution Mutations Atmospheric circulation anomaly

Experts’Consensus on the Management of Respiratory Disease Syndemic

在线全文

学校读者我要写书评

暂无评论

China CDC weekly 2024年第8期6卷 131-138页

作者： Weizhong Yang Zhongjie Li Ting Yang yanming Li Zhengde Xie Luzhao Feng Zhibin Peng Jue Liu School of Population Medicine and Public Health Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina State Key Laboratory of Respiratory Health and Multimorbidity BeijingChina Key Laboratory of Pathogen Infection Prevention and Control Peking Union Medical CollegeMinistry of EducationBeijingChina National Center for Respiratory Diseases State Key Laboratory of Respiratory Health and MultimorbidityNational Clinical Research Center for Respiratory DiseasesInstitute of Respiratory MedicineChinese Academy of Medical SciencesDepartment of Pulmonary and Critical Care MedicineCenter of Respiratory MedicineChina-Japan Friendship HospitalBeijingChina Department of Pulmonary and Critical Care Medicine National Center of GerontologyBeijing HospitalInstitute of Geriatric MedicineChinese Academy of Medical SciencesBeijingChina Beijing Key Laboratory of Pediatric Respiratory Infection Diseases Key Laboratory of Major Diseases in ChildrenMinistry of EducationNational Clinical Research Center for Respiratory DiseasesResearch Unit of Critical Infection in ChildrenChinese Academy of Medical Sciences2019RU016National Key Discipline of Pediatrics(Capital Medical University)Beijing Pediatric Research InstituteBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina Chinese Center for Disease Control and Prevention BeijingChina Department of Epidemiology and Biostatistics School of PublicHealthKey Laboratory of Epidemiology of Major DiseasesMinistry of EducationPeking University Health Science Center-Weifang Joint Research Center for Maternal and Child HealthPeking UniversityBeijingChina

The global burden of respiratory diseases is a significant and increasing threat to individuals *** 2017,there were 544.9 million cases of chronic respiratory diseases,a 39.8%increase since 1990(1).These diseases were the third leading cause of global mortality in 2017,accounting for 7.0%of all deaths,an 18.0%increase compared to 1990.

关键词： diseases respiratory mortality