检索结果-南通市图书馆

Microphysical Characteristics of Rainfall Based on Long-Term Observations with a 2DVD in Yangbajain,Tibet

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第9期41卷 1721-1734页

作者： Ming LI Yongheng BI Yonghai SHEN Yinan WANG Ciren Nima Tianlu CHEN Daren LYU key laboratory for Cosmic rays of the Ministry of Education Tibet UniversityLhasa 850000China key laboratory of Middle Atmosphere and Global Environment Observation(LAGEO) Institute of Atmospheric PhysicsChinese Academy of ScienceBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

Raindrop size distribution(DSD)plays a crucial role in enhancing the accuracy of radar quantitative precipitation estimates in the Tibetan Plateau(TP).However,there is a notable scarcity of long-term,high-resolution observations in this *** address this issue,long-term observations from a two-dimensional video disdrometer(2DVD)were leveraged to refine the radar and satellite-based algorithms for quantifying precipitation in the hinterland of the *** was observed that weak precipitation(R<1,mm h-1)accounts for 86%of the total precipitation time,while small raindrops(D<2 mm)comprise 99%of the total raindrop ***,the average spectral width of the DSD increases with increasing rain *** DSD characteristics of convective and stratiform precipitation were discussed across five different rain rates,revealing that convective precipitation in Yangbajain(YBJ)exhibits characteristics similar to maritime-like *** constrained relationships between the slopeΛand shapeμ,D_(m)and N_(w)of gamma DSDs were ***,we established a correlation between the equivalent diameter and drop axis ratio and found that raindrops on the TP attain a nearly spherical ***,the application of the rainfall retrieval algorithms of the dual-frequency precipitation radar in the TP is improved based on the statistical results of the DSD.

关键词： Tibetan Plateau raindrop size distribution 2DVD dual frequency radar microphysical features

A novel trigger algorithm for wide-field-of-view imaging atmospheric Cherenkov technique experiments

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2022年第3期33卷 22-28页

作者： Guang-Guang Xin Hao Cai Yi-Qing Guo Tian-Lu Chen Cheng Liu Xiang-Li Qian School of Physics and Technology Wuhan UniversityWuhan 430072China key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Ministry of Education The Key Laboratory of Cosmic Rays(Tibet University)Lhasa 850000China School of Intelligent Engineering Shandong Management UniversityJinan 250357China

The high-altitude detection of astronomical radiation(HADAR)experiment is a new Cherenkov observation technique with a wide field of view(FoV),aimed at observing the prompt emissions ofγ-ray bursts(GRBs).The bottleneck for this type of experiment can be found in determining how to reject the high rate of nightsky background(NSB)noise from random *** this work,we propose a novel method for rejecting noise,which considers the spatial properties of GRBs and the temporal characteristics of Cherenkov *** space coordinates,the map between the celestial sphere and the fired photomultiplier tubes(PMTs)on the telescope's camera can be expressed as f(δ(i,j))=δ'(i',j'),which means that a limited number of PMTs is selected from one *** the temporal scale,a 20-ns time window was selected based on the knowledge of Cherenkov *** allowed integration of the NSB for a short time ***,the angular resolution and effective area at 100 GeV in the HADAR experiment were obtained as 0.2°and 10^(4)m^(2),*** method can be applied to all wide-FoV experiments.

关键词： IACTs Wide field of view(FoV) γ-ray burst Cherenkov radiation

Cosmic ray electron spectrum due to the dispersion of injection spectrum

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2018年第7期42卷 89-93页

作者： Tian-Lu Chen Wei Liu Qi Gao Mao-Yuan Liu Hai-Jin Li Danzengluobu Ying Shi School of Physics and Technology Wuhan University Wuhan 430072 China Physics Department of the Science School Tibet University Lhasa 850000 China key laboratory of Cosmic rays（Tibet University） Ministry of Education Lhasa 850000 China key laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

The cosmic-ray total electron spectrum （electrons plus positrons） has been measured precisely up to TeV energies, with more interesting features found. Exhaustive analyses of the electron spectrum strongly support a spectral hardening above 100 GeV, rather than a featureless single power-law, which is confirmed by the most recent observations. Meanwhile, the measurements of the DAMPE satellite have verified the presence of a knee-like structure around 1 TeV in the electron spectrum, resembling the cosmic-ray knee. In this paper, we establish a physical model in which the observed electron spectrum is composed of a superposition of CR sources with various spectral indices and high-energy cutoffs. The dispersion of the power index is assumed to be Gaussian, while the cutoff energy Ec follows a power-law distribution. These simple ideas can account naturally for both the hundred-GeV excess and the TeV spectral break.

关键词： electron spectrum cosmic rays source DAMPE

Research on the knee region of cosmic ray by using a novel type of electron-neutron detector array

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2024年第4期19卷 13-24页

作者： Bing-Bing Li Xin-Hua Ma Shu-Wang Cui Hao-Kun Chen Tian-Lu Chen Danzengluobu Wei Gao Hai-Bing Hu Denis Kuleshov Kirill Kurinov Hu Liu Mao-Yuan Liu Ye Liu Da-Yu Peng Yao-Hui Qi Oleg Shchegolev Yuri Stenkin Li-Qiao Yin Heng-Yu Zhang Liang-Wei Zhang College of Physics Hebei Normal UniversityShijiazhuang 050024China key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China TIANFU Cosmic Ray Research Center Chengdu 610000China College of Science Tibet UniversityLhasa 850000China key laboratory of comic rays Ministry of EducationTibet UniversityLhasa 850000China Institute for Nuclear Research of the Russian Academy of Sciences Moscow 117312Russia School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China School of Management Science and Engineering Hebei University of Economics and BusinessShijiazhuang 050061China Moscow Institute of Physics and Technology Moscow 141700Russia

By accurately measuring composition and energy spectrum of cosmic ray,the origin problem of so called“knee”region(energy>one PeV)can be ***,up to the present,the results of the spectrum in the knee region obtained by several previous experiments have shown obvious differences,so they cannot give effective evidence for judging the theoretical models on the origin of the ***,the Large High Altitude Air Shower Observatory(LHAASO)has reported several major breakthroughs and important results in astro-particle physics *** on its advantages of wide-sky survey,high altitude location and large area detector arrays,the research content of LHAASO experiment mainly includes ultra high-energy gamma-ray astronomy,measurement of cosmic ray spectra in the knee region,searching for dark matter and new phenomena of particle physics at higher *** electron and thermal neutron detector(EN-Detector)is a new scintillator detector which applies thermal neutron detection technology to measure cosmic ray extensive air shower(EAS).This technology is an extension of *** EN-Detector Array(ENDA)can highly efficiently measure thermal neutrons generated by secondary hadrons so called“skeleton”of *** this paper,we perform the optimization of ENDA configuration,and obtain expectations on the ENDA results,including thermal neutron distribution,trigger efficiency and capability of cosmic ray composition *** obtained real data results are consistent with those by the Monte Carlo simulation.

关键词： cosmic ray EAS knee region LHAASO ENDA

Unveiling Cloud Vertical Structures over the Interior Tibetan Plateau through Anomaly Detection in Synergetic Lidar and Radar Observations

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

Advances in Atmospheric Sciences 2024年第12期41卷 2381-2398页

作者： Wei ZHAO Yinan WANG Yongheng BI Xue WU Yufang TIAN Lingxiao WU Jingxuan LUO Xiaoru HU Zhengchao QI Jian LI Yubing PAN Daren LYU key laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China key laboratory for Cosmic rays of the Ministry of Education Tibet UniversityLhasa 850000China School of Ecology and Environment Tibet UniversityLhasa 850000China State key laboratory of Severe Weather Institute of Tibetan Plateau MeteorologyChinese Academy of Meteorological SciencesBeijing 100081China Institute of Urban Meteorology Chinese Meteorological AdministrationBeijing 100089China

Cloud vertical structure(CVS)strongly affects atmospheric circulation and radiative ***,long-term,groundbased observations are scarce over the Tibetan Plateau(TP)despite its vital role in global *** study utilizes ground-based lidar and Ka-band cloud profiling radar(KaCR)measurements at Yangbajain(YBJ),TP,from October 2021 to September 2022 to characterize cloud properties.A satisfactorily performing novel anomaly detection algorithm(LevelShiftAD)is proposed for lidar and KaCR profiles to identify cloud *** base heights(CBH)retrieved from KaCR and lidar observations show good consistency,with a correlation coefficient of 0.78 and a mean difference of-0.06 *** top heights(CTH)derived from KaCR match the FengYun-4A and Himawari-8 products ***,KaCR measurements serve as the primary dataset for investigating CVSs over the *** diurnal cycles occur in summer and *** diurnal cycle is characterized by a pronounced increase in cloud occurrence frequency in the afternoon with an early-morning decrease in winter,while cloud amounts remain high all day,with scattered nocturnal increases in *** features more frequent clouds with larger geometrical thicknesses,a higher multi-layer ratio,and greater inter-cloud *** 26%of the cloud bases occur below 0.5 *** exhibits a bimodal distribution of cloud base heights with peaks at 0-0.5 km and 2-2.5 ***-layer and geometrically thin clouds prevail at *** study enriches long-term measurements of CVSs over the TP,and the robust anomaly detection method helps quantify cloud macro-physical properties via synergistic lidar and radar observations.

关键词： Ka-band cloud profiling radar lidar anomaly detection cloud base heights cloud top heights Tibetan Plateau

A GPU Algorithm for Solving the Positions of New Pulsars

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11期24卷 46-52页

作者： Ziyao Fang Weiwei Zhu Chenchen Miao Yukai Zhou Dejiang Zhou Tianlu Chen Qiuyang Fu Lingqi Meng Xueli Miao Jiarui Niu Mengyao Xue The key laboratory of Cosmic rays(Tibet University) Ministry of EducationLhasa 850000China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China School of Physics Peking UniversityBeijing 100871China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

Timing newly discovered pulsars requires gradually building up a timing model that connects observations taken days to months *** sometimes can be challenging when our initial knowledge of the pulsar’s position is arcminutes off from its true *** a position error leads to significant arrival time shifts as a result of the Earth’s orbital *** down-hill fitting timing algorithms become ineffective when our model predicts the wrong pulse rotations for our next *** some pulsars whose model prediction is not too far off,the correct rotation number could be found by trial-and-error *** the remaining challenging pulsars,a more generalized method is called *** paper proposes a GPU-based algorithm that could exhaustively search a large area of trail positions for probable timing *** could help find phase-connected timing solutions for new pulsars using brute force.

关键词： methods data analysis-(stars:)pulsars general-(stars:)pulsars individual J0706+2707,J2149+5643

Deep-reinforcement-learning-based water diversion strategy

在线全文

学校读者我要写书评

暂无评论

Environmental Science and Ecotechnology 2024年第1期17卷 68-79页

作者： Qingsong Jiang Jincheng Li Yanxin Sun Jilin Huang Rui Zou Wenjing Ma Huaicheng Guo Zhiyun Wang Yong Liu State Environmental Protection key laboratory of All Materials Flux in River Ecosystems College of Environmental Sciences and EngineeringPeking UniversityBeijing100871PR China rays Computational Intelligence Lab Beijing Inteliway Environmental Ltd.Beijing100085PR China Yunnan key laboratory of Pollution Process and Management of Plateau Lake-Watershed Yunnan Research Academy of Eco-environmental SciencesKunming650034PR Chin

Water diversion is a common strategy to enhance water quality in eutrophic lakes by increasing available water resources and accelerating nutrient *** effectiveness depends on changes in the source water and lake ***,the challenge of optimizing water diversion remains because it is difficult to simultaneously improve lake water quality and minimize the amount of diverted ***,we propose a new approach called dynamic water diversion optimization(DWDO),which combines a comprehensive water quality model with a deep reinforcement learning *** applied DWDO to a region of Lake Dianchi,the largest eutrophic freshwater lake in China and validated *** results demonstrate that DWDO significantly reduced total nitrogen and total phosphorus concentrations in the lake by 7%and 6%,respectively,compared to previous ***,annual water diversion decreased by an impressive 75%.Through interpretable machine learning,we identified the impact of meteorological indicators and the water quality of both the source water and the lake on optimal water *** found that a single input variable could either increase or decrease water diversion,depending on its specific value,while multiple factors collectively influenced real-time adjustment of water ***,using well-designed hyperparameters,DWDO proved robust under different uncertainties in model *** training time of the model is theoretically shorter than traditional simulation-optimization algorithms,highlighting its potential to support more effective decisionmaking in water quality management.

关键词： Dynamic water diversion optimization Deep reinforcement learning Process-based model Explainable decision-making Parameter uncertainty

Variable Stars in the 50BiN Open Cluster Survey.Ⅲ.NGC 884

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

Research in Astronomy and Astrophysics 2024年第2期24卷 36-45页

作者： Lin-Hong Wang Qian-Heng Nie Kun Wang Xiao-Dian Chen Chun-Guang Zhang Li-Cai Deng Xiao-Bin Zhang Tian-Lu Chen Department of Physics College of ScienceTibet UniversityLhasa 850000China key laboratory of Cosmic rays Tibet UniversityMinistry of EducationLhasa 850000China key laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Middlesex School ConcordMassachusettsUnited States of America School of Physics and Astronomy China West Normal UniversityNanchong 637002China

Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky *** stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host *** most powerful tool for such studies is time-domain photometric *** paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC *** target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally *** the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were *** detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown *** new variable stars were discovered in this *** also compared the variable star content of NGC 884 with its companion NGC 869.

关键词： stars variables general-(Galaxy:)open clusters and associations individual(…,…)-(stars:)binaries general

Atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering correction

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第3期35卷 40-52页

作者： Ding-Han Zhu Xiong Zhang Xiao-Qiang Li Peng Li Yan-Bin Wang Shuang Zhang State key laboratory of NBC Protection for Civilian Beijing 102205China

In high-altitude nuclear detonations,the proportion of pulsed X-ray energy can exceed 70%,making it a specific monitoring signal for such *** pulsed X-rays can be captured using a satellite-borne X-ray detector following atmospheric *** quantitatively analyze the effects of different satellite detection altitudes,burst heights,and transmission angles on the physical processes of X-ray transport and energy fluence,we developed an atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering *** proposed method is an improvement over the traditional analytical method that only computes direct-transmission *** traditional analytical method exhibits a maximum relative error of 67.79% compared with the Monte Carlo *** improved method reduces this error to within 10% under the same conditions,even reaching 1% in certain ***,its computation time is 48,000 times faster than that of the Monte Carlo *** results have important theoretical significance and engineering application value for designing satellite-borne nuclear detonation pulsed X-ray detectors,inverting nuclear detonation source terms,and assessing ionospheric effects.

关键词： High-altitude nuclear detonation Atmospheric transmission Pulsed X-rays Scattering correction Analytical method Monte Carlo method