检索结果-南通市图书馆

Quantitative Analysis of Seeing with Height and Time at Muztagh-Ata Site Based on ERA5 Database

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第1期24卷 87-95页

作者： Xiao-Qi Wu Cun-Ying Xiao Ali Esamdin Jing Xu Ze-Wei Wang Luo Xiao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

Seeing is an important index to evaluate the quality of an astronomical *** estimate seeing at the Muztagh-Ata site with height and time quantitatively,the European Centre for Medium-Range Weather Forecasts reanalysis database(ERA5)is *** calculated from ERA5 is compared consistently with the Differential Image Motion Monitor seeing at the height of 12 *** show that seeing decays exponentially with height at the Muztagh-Ata *** decays the fastest in fall in 2021 and most slowly with height in *** seeing condition is better in fall than in *** median value of seeing at 12 m is 0.89 arcsec,the maximum value is1.21 arcsec in August and the minimum is 0.66 arcsec in *** median value of seeing at 12 m is 0.72arcsec in the nighttime and 1.08 arcsec in the *** is a combination of annual and about biannual variations with the same phase as temperature and wind speed indicating that seeing variation with time is influenced by temperature and wind *** Richardson number Ri is used to analyze the atmospheric stability and the variations of seeing are consistent with Ri between *** quantitative results can provide an important reference for a telescopic observation strategy.

关键词： site testing atmospheric effects methods:data analysis telescopes Earth

Raindrop Size Distributions in the Zhengzhou Extreme Rainfall Event on 20 July 2021:Temporal-Spatial Variability and Implications for Radar QPE

在线全文

学校读者我要写书评

暂无评论

Journal of Meteorological Research 2024年第3期38卷 489-503页

作者： Liman CUI Haoran LI Aifang SU Yang ZHANG Xiaona LYU Le XI Yuanmeng ZHANG Henan Key Laboratory of Agrometeorological Support and Applied Technique China Meteorological AdministrationZhengzhou450003China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing100081China Henan Meteorological observatory Zhengzhou450003China

In this study,a regional Parsivel OTT disdrometer network covering urban Zhengzhou and adjacent areas is employed to investigate the temporal-spatial variability of raindrop size distributions(DSDs)in the Zhengzhou extreme rainfall event on 20 July *** rain rates observed by disdrometers and rain gauges from six operational sites are in good agreement,despite significant site-to-site variations of 24-h accumulated rainfall ranging from 198.3 to 624.1 *** Parsivel OTT observations show prominent temporal-spatial variations of DSDs,and the most drastic change was registered at Zhengzhou Station where the record-breaking hourly rainfall of 201.9 mm over 1500-1600 LST(local standard time)was *** hourly rainfall is characterized by fairly high concentrations of large raindrops,and the mass-weighted raindrop diameter generally increases with the rain rate before reaching the equilibrium state of DSDs with the rain rate of about 50 mm h^(−1).Besides,polarimetric radar observations show the highest differential phase shift(K_(dp))and differential reflectivity(Z_(dr))near surface over Zhengzhou Station from 1500 to 1600 *** light of the remarkable temporal-spatial variability of DSDs,a reflectivity-grouped fitting approach is proposed to optimize the reflectivity-rain rate(Z-R)parameterization for radar quantitative precipitation estimation(QPE),and the rain gauge measurements are used for *** results show an increase of mean bias ratio from 0.57 to 0.79 and a decrease of root-mean-square error from 23.69 to 18.36 for the rainfall intensity above 20.0 mm h^(−1),as compared with the fixed Z-R *** study reveals the drastic temporal-spatial variations of rain microphysics during the Zhengzhou extreme rainfall event and warrants the promise of using reflectivity-grouped fitting Z-R relationships for radar QPE of such events.

关键词： extreme rainfall raindrop size distribution radar quantitative precipitation estimation(QPE)

在线全文

学校读者我要写书评

暂无评论

The FAST Core Array

Astronomical Techniques and Instruments 2024年第2期1卷 84-94页

作者： Peng Jiang Rurong Chen Hengqian Gan Jinghai Sun Boqin Zhu Hui Li Weiwei Zhu Jingwen Wu Xuelei Chen Haiyan Zhang Tao An National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Guizhou Radio Astronomical observatory Guizhou UniversityGuiyang 550000China Shanghai Astronomical observatory Chinese Academy of SciencesShanghai 200030China

The Five-hundred-meter Aperture Spherical Radio Telescope(FAST)Core Array is a proposed extension of FAST,integrating 24 secondary 40-m antennas implanted within 5 km of the FAST *** original array design will combine the unprecedented sensitivity of FAST with a high angular resolution(4.3"at a frequency of 1.4 GHz),thereby exceeding the capabilities at similar frequencies of next-generation arrays such as the Square Kilometre Array Phase 1 or the next-generation Very Large *** article presents the technical specifications of the FAST Core Array,evaluates its potential relatively to existing radio telescope arrays,and describes its expected scientific *** proposed array will be equipped with technologically advanced backend devices,such as real-time signal processing systems.A phased array feed receiver will be mounted on FAST to improve the survey efficiency of the FAST Core Array,whose broad frequency coverage and large field of view(FOV)will be essential to study transient cosmic phenomena such as fast radio bursts and gravitational wave events,to conduct surveys and resolve structures in neutral hydrogen galaxies,to monitor or detect pulsars,and to investigate exoplanetary ***,the FAST Core Array can strengthen China's major role in the global radio astronomy community,owing to a wide range of potential scientific applications from cosmology to exoplanet science.

关键词： FAST Radio telescope Interferometry Synthesis array

Multi-granularity feature enhancement network for maritime ship detection

在线全文

学校读者我要写书评

暂无评论

CAAI Transactions on Intelligence Technology 2024年第3期9卷 649-664页

作者： Li Ying Duoqian Miao Zhifei Zhang Hongyun Zhang Witold Pedrycz Department of Computer Science and Technology Tongji UniversityShanghaiChina Project Management Office of China National Scientific Seafloor observatory Tongji UniversityShanghaiChina Department of Electrical and Computer Engineering AlbertaEdmontonCanada System Research Institute Polish Academy of SciencesWarsawPoland

Due to the characteristics of high resolution and rich texture information,visible light images are widely used for maritime ship ***,these images are suscep-tible to sea fog and ships of different sizes,which can result in missed detections and false alarms,ultimately resulting in lower detection *** address these issues,a novel multi-granularity feature enhancement network,MFENet,which includes a three-way dehazing module(3WDM)and a multi-granularity feature enhancement module(MFEM)is *** 3WDM eliminates sea fog interference by using an image clarity automatic classification algorithm based on three-way decisions and FFA-Net to obtain clear image ***,the MFEM improves the accuracy of detecting ships of different sizes by utilising an improved super-resolution reconstruction con-volutional neural network to enhance the resolution and semantic representation capa-bility of the feature maps from *** results demonstrate that MFENet surpasses the other 15 competing models in terms of the mean Average Pre-cision metric on two benchmark datasets,achieving 96.28%on the McShips dataset and 97.71%on the SeaShips dataset.

关键词： object classification object recognition rough sets rough set theory

Comparison of ERA5 turbulent fluxes at the air-sea interface with measurements from a wave-following platform

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Atmospheric and Oceanic Science Letters 2024年第3期 34-38页

作者： Sa?d Benjeddou Denis Bourras Christopher Luneau Aix Marseille Université National Center for Scientific ResearchMediterranean Institute of Oceanography observatory of the Sciences of the Universe Pythéas Institute National Center for Scientific Research

Turbulent fluxes at the air-sea interface were estimated with data collected in 2011-2020 with a low-profile platform named OCARINA during eight experiments in five regions:2011,2015,and 2016 in the Iroise Sea;2012 in the tropical Atlantic;2014 in the Chilie-Peru upwelling;2017 and 2018 in the Mediterranean Sea,and 2018 and 2020 in *** observations were carried out with moderate winds(2-10 m s-1) and average wave heights of 1.5 *** this study,the authors used the fluxes calculated by the bulk method using OCARINA-sampled data as the *** data can validate the fluxes estimated from ERAS reanalysis *** OCARINA and ERA5 data were taken *** do this,the authors established an algorithm to extract the OCARINA data as closely as possible to the reanalysis data in time and *** measurements of the OCARINA platform can conclude on the relevance of the widely used reanalysis data.

关键词：

Black holes as the source of dark energy:A stringent test with high-redshift JWST AGNs

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 181-188页

作者： Lei Lei Lei Zu Guan-Wen Yuan Zhao-Qiang Shen Yi-Ying Wang Yuan-Zhu Wang Zhen-Bo Su Wen-Ke Ren Shao-Peng Tang Hao Zhou Chi Zhang Zhi-Ping Jin Lei Feng Yi-Zhong Fan Da-Ming Wei Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China

Studies have proposed that there is evidence for cosmological coupling of black holes(BHs)with an index of k≈3;hence,BHs serve as the astrophysical source of dark ***,the data sample is limited for the redshifts of≤*** recent years,the James Webb Space Telescope(JWST)has detected many high-redshift active galactic nuclei(AGNs)and *** the JWST NIRSpec-/NIRCam-resolved AGNs,three are determined to be in early-type host galaxies with a redshift of z~***,their M_(*)and MBH are in tension with the predicted cosmological coupling of black holes with k=3 at a confidence level of~2σ,which challenges the hypothesis that BHs serve as the origin of dark *** work on high-redshift AGNs using the JWST will further assess such a hypothesis by identifying more early-type host galaxies in the higher mass range.

关键词： dark energy supermassive black hole active galactic nuclei James Webb Space Telescope

Long-lived lunar volcanism sustained by precession-driven core-mantle friction

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第2期11卷 114-123页

作者： Shuoran Yu Xiao Xiao Shengxia Gong Nicola Tosi Jun Huang Doris Breuer Long Xiao Dongdong Ni State Key Laboratory of Lunar and Planetary Sciences Macau University of Science and Technology Planetary Science Institute State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences China University of Geosciences CAS Key Laboratory of Planetary Sciences Shanghai Astronomical Observatory Institute of Planetary Research German Aerospace Centre(DLR)

Core-mantle friction induced by the precession of the Moon's spin axis is a strong heat source in the deep lunar mantle during the early phase of a satellite's evolution, but its influence on the long-term thermal evolution still remains poorly explored. Using a one-dimensional thermal evolution model, we show that core-mantle friction can sustain global-scale partial melting in the upper lunar mantle until ～3.1 Ga, thus accounting for the intense volcanic activity on the Moon before ～3.0 Ga. Besides, core-mantle friction tends to suppress the secular cooling of the lunar core and is unlikely to be an energy source for the long-lived lunar core dynamo. Our model also favours the transition of the Cassini state before the end of the lunar magma ocean phase(～4.2 Ga), which implies a decreasing lunar obliquity over time after the solidification of the lunar magma ocean. Such a trend of lunar obliquity evolution may allow volcanically released water to be buried in the lunar regolith of the polar regions. As a consequence, local water ice could be more abundant than previously thought when considering only its accumulation caused by solar wind and comet spreading.

关键词： Moon precession orbit volcanism

Influence of self-similar stresses on scenario earthquake construction:An example along the Tanlu Fault

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第5期67卷 1687-1697页

作者： Feng HU Huajian YAO Houyun YU Zeyu LU Jieyi HOU Song LUO Zhigang SHAO Xiaofei CHEN School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Mengcheng Geophysical National Field Scientific observatory Hefei 230026China Department of Earth and Space Science Southern University of Science and TechnologyShenzhen 518055China Institute of Earthquake Prediction China Earthquake AdministrationBeijing 100036China

As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern *** is important to improve the understanding of seismic hazard assessments in areas near *** start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu *** fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake *** the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation *** findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake *** compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial *** the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip *** response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.

关键词： Scenario earthquakes Self-similar stress Tanlu Fault Dynamic rupture Ground motion

Cascading multi-segment rupture process of the 2023 Turkish earthquake doublet on a complex fault system revealed by teleseismic P wave back projection method

在线全文

学校读者我要写书评

暂无评论

Earthquake Science 2024年第2期37卷 158-173页

作者： Bonan Cao Zengxi Ge Department of Geophysics School of Earth and Space SciencesPeking UniversityBeijing 100871China Hebei Hongshan National Geophysical observatory for Thick Sediments and Seismic Hazards Peking UniversityBeijing 100871China

In this study,the vertical components of broadband teleseismic P wave data recorded by China Earthquake Network are used to image the rupture processes of the February 6th,2023 Turkish earthquake doublet via back projection *** in two frequency bands(0.5-2 Hz and 1-3 Hz)are used in the imaging *** results show that the rupture of the first event extends about 200 km to the northeast and about 150 km to the southwest,lasting~90 s in *** southwestern rupture is triggered by the northeastern rupture,demonstrating a sequential bidirectional unilateral rupture *** rupture of the second event extends approximately 80 km in both northeast and west directions,lasting~35 s in total and demonstrates a typical bilateral rupture *** cascading ruptures on both sides also reflect the occurrence of selective rupture behaviors on bifurcated *** addition,we observe super-shear ruptures on certain fault sections with relatively straight fault structures and sparse aftershocks.

关键词： 2023 Turkish earthquake doublet back projection method cascading segmented rupture process coseismic triggering super-shear ruptures