检索结果-南通市图书馆

Forecast of cosmological constraints with type Ia supernovae from the Chinese Space station Telescope

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2023年第2期66卷 131-139页

作者： Shi-Yu Li Yun-Long Li Tianmeng Zhang Jozsef Vink Eniko Regos Xiaofeng Wang Gaobo Xi Hu Zhan Beijing Planetarium Beijing Academyof Scienceand TechnologyBeijing 100044China National Space Science Center Chinese Academyof SciencesBeijing 100190China National Space ScienceData Centerof China Beijing 101407China Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 1oo10lChina School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 101408China Konkoly Observatory Konkoly Institute of AstronomyKonkoly Thege M.ut 15-17Budapest 1121Hungary ELTE Eotvos Lorand University Institute of PhysicsPazmany Peter setany I/ABudapest 1117Hungary Institute of Physics Universityof SzegedDom ter9Szeged 6720Hungary Physics Department and Tsinghua Center for Astrophysics(THCA) Tsinghua UniversityBeijing 100084China Kavli Institute forAstronomy and Astrophysics Peking UniversityBeijingio0871China

The 2-m aperture Chinese Space station Telescope(CSST),which observes at wavelengths ranging from 255 to 1000 nm,is expected to start science operations in 2024.An ultra-deep field observation program covering approximately 10 deg2is proposed with supernovae(SNe) and other transients as one of its primary science drivers.This paper presents the simulated detection results of type Ⅰa supernovae(SNe Ⅰa) and explores the impact of new datasets on the determinations of cosmological parameters.The simulated observations are conducted with an exposure time of 150 s and cadences of 10,20,and 30 d.The survey mode covering a total of 80 observations but with a random cadence in the range of 4 to 14 d is also explored.Our simulation results indicate that the CSST can detect up to ~1800 SNe la at z <1.3.The simulated SNe la are then used to constrain the cosmological parameters.The constraint on can be improved by 37.5% using the 10-d cadence sample in comparison with the Pantheon sample.A deeper measurement simulation with a 300 s exposure time together with the Pantheon sample improves the current constraints on Ωmby 58.3% and ω by 47.7%.Taking future lager sets of nearby SN Ⅰa sample form ground-based surveys(i.e.,N~3400) into consideration,the constraints on ω can be improved by 59.1%.The CSST ultra-deep field observation program is expected to discover large amounts of SNe la over a broad redshift span and enhance our understanding of the nature of dark energy.

关键词： supernovae survey station

Tropospheric NO_2 vertical column densities retrieved from ground-based MAX-DOAS measurements at Shangdianzi regional atmospheric background station in China

在线全文

学校读者我要写书评

暂无评论

环境科学学报：英文版 2019年第6期31卷 186-196页

作者： Siyang Cheng Jianzhong Ma Weiping Cheng Peng Yan Huaigang Zhou Liyan Zhou Peng Yang State Key Laboratory of Severe Weather & CMA Key Laboratory of Atmospheric Chemistry Chinese Academy of Meteorological Sciences China Waterborne Transport Research Institute CMA Meteorological Observation Centre Shangdianzi Regional Air Background station Beijing Meteorological Bureau Meteorological Bureau of Shijiazhuang

Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10^(16)molec/cm^2)in February and the minimum(3.5×10^(15)molec/cm^2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.

关键词： Ground-basedMAX-DOAS Tropospheric NO2 Satellite validation Pollution plume Regional atmospheric background station

Optimal sizing of PV and battery-based energy storage in an offgrid nanogrid supplying batteries to a battery swapping station

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 309-320页

作者： Mingfei BAN Jilai YU Mohammad SHAHIDEHPOUR Danyang GUO Harbin Institute of Technology Harbin 150001China Robert W.Galvin Center for Electricity Innovation Illinois Institute of Technology10 W 35th Street#1600ChicagoILUSA

Nanogrids are expected to play a significant role in managing the ever-increasing distributed renewable energy sources. If an off-grid nanogrid can supply fullycharged batteries to a battery swapping station(BSS)serving regional electric vehicles(EVs), it will help establish a structure for implementing renewable-energyto-vehicle systems. A capacity planning problem is formulated to determine the optimal sizing of photovoltaic(PV) generation and battery-based energy storage system(BESS) in such a nanogrid. The problem is formulated based on the mixed-integer linear programming(MILP)and then solved by a robust optimization approach. Flexible uncertainty sets are employed to adjust the conservativeness of the robust optimization, and Monte Carlo simulations are carried out to compare the performance of the solutions. Case studies demonstrate the merits of the proposed applications and verify the approach.

关键词： Nanogrid Battery swapping station Electric vehicle Renewable energy

Length optimization of straight line connecting turnout on main line in high-speed railway station yard

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2017年第5期24卷 1111-1120页

作者：尹国栋时瑾魏庆朝来琳 School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China China Railway Design Corporation Tianjin 300142China

Taking the development of high-speed railway in China as background, and referring to the dynamic theory and wheel-rail contact mode, dynamic analysis model was established, considering the setting position of straight lines and running conditions of train in high-speed railway station yard. Using the established model, and choosing vehicle lateral acceleration and wheel suspension as the evaluation indexes, dynamic characteristic of vehicle traveling in turnout and adjacent area on main line was analyzed, and effects on travelling safety and stability of train aroused by length variation of straight lines were calculated based on analyzing the damping rules of vibration. The results show that, a certain length of straight lines can alleviate the vibration aroused in turnout and curve(turnout), length of straight lines connecting turnouts in different sections on main line was proposed to meet the demand of traveling stability, and shortening or cancelation of straight line for the scale limitation of station yard has less influence on operation safety of train.

关键词： high-speed railway station yard straight line turnout dynamic theory length optimization

Optimization model and algorithm for system operation division of labor at two-way marshaling station

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 1998年第5期41卷 511-518页

作者：牛惠民胡安洲 Department of Transportation Management Engineering Northern Jiaotong University Beijing China

Based on the systematic analysis of the operation process at two-way marshaling station, the operation ways of through car flows, sorting car flows and loading car flows are comprehensively studied. An optimal model of system operation division of labor based on resource constraint is constructed. The model is solved by using genetic algorithm, and the improving strategy for solving the model is proposed. The application example indicates that the model and algorithm can effectively solve the problem of operation division of labor at two-way marshaling station.

关键词： two-way marshaling station operation division of labor car flows joining operation process model genetic algorithm.

Performance enhancement of water bath heater at natural gas city gate station using twisted tubes

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2020年第1期28卷 165-179页

作者： P.Soleimani M.Khoshvaght-Aliabadi H.Rashidi H.Bahmanpour Department of Chemical Engineering Shahrood BranchIslamic Azad UniversityShahroodIran Department of Environment Shahrood BranchIslamic Azad UniversityShahroodIran

Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). Before the pressure reduction process, the temperature of natural gas is increased usually by using a water bath heater,which burns natural gas as fuel, to protect against freezing of natural gas. These types of heat exchangers have a low efficiency and consume a lot of fuel to generate the required heat. In the current study, the twisted configuration of the heating coil is proposed and investigated to enhance the heat transfer through a water bath heater with a nominal capacity of 1000 m^3·h^-1. Firstly, the implementation procedure is validated with data collected from the CGS of Qaleh-Jiq(located in Golestan province of Iran). A very good agreement is achieved between the obtained results and the real data. Then, three different twist ratios are considered to examine the twisting effects. The proposed technique is evaluated in the terms of velocity, temperature, and pressure variations, and the results are compared with the conventional case, i.e. straight configuration. It is found that both the heat transfer rate and the pressure drop augment as the twist ratio is raised. Finally, it is concluded that the twisted tubes can reduce the length of the gas coil by about 12.5% for the model with low twist ratio, 18.75% for the model with medium twist ratio, and 25% for the model with high twist ratio as compared to the straight configuration.

关键词： Natural gas city gate station Water bath heater Heat transfer enhancement Twisted tube

Mechanism of toppling and deformation in hard rock slope: a case of bank slope of Hydropower station, Qinghai Province, China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2019年第4期16卷 924-934页

作者： CAI Jun-chao JU Neng-pan HUANG Run-qiu ZHENG Da ZHAO Wei-hua LI Long-qi HUANG Jian State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology College of Environment and Civil Engineering Chengdu University of Technology

Recently, various toppling slopes have emerged with the development of hydropower projects in the western mountainous regions of China. The slope on the right bank of the Laxiwa Hydropower station, located on the mainstream of the Yellow River in the Qinghai Province of Northwest China, is a typical hard rock slope. Further, its deformation characteristics are different from those of common natural hard rock toppling. Because this slope is located close to the dam of the hydropower station, its deformation mechanism has a practical significance. Based on detailed geological engineering surveys, four stages of deformation have been identified using discrete element numerical software and geological engineering analysis methods, including toppling creep, initial toppling deformation, intensified toppling deformation, and current slope formation. The spatial and time-related deformation of this site also exhibited four stages, including initial toppling, toppling development, intensification of toppling, and disintegration and collapse. Subsequently, the mechanism of toppling and deformation of the bank slope were studied. The results of this study exhibit important reference value for developing the prevention–control design of toppling and for ensuring operational safety in the hydropower reservoir area.

关键词： Laxiwa Hydropower station Hard rock slope Toppling Deformation mechanism Discrete element method Slope failure

Observational Study of Annual Variations of the Surface Energy Balance Components at Zhongshan station of Antarctica in 1990

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 1993年第8期36卷 976-987页

作者：卞林根贾朋群陆龙骅周秀骥 Polar Meteorological Research Laboratory of Chinese Academy of Meteorological Sciences Beijing 100081 PRC

From February 1990 to January 1991, the measurement experiment was carried out at Zhongshan station, East Antarctica. In the experiment, measurements of the surface radiative fluxes and wind, temperature and humidity profiles in the lowest 32 m in the atmosphere boundary layer were made throughout the year. The regime of the surface energy balance was analysed based on the observed data. The conclusion was derived that in warm season (from Nov. to Feb.), large amounts of energy are absorbed by the surface and then transported to the atmosphere in the form of sensible and latent heat, while in cold season (from Mar. to Oct.) continually radiative cooling of the surface occurs.

关键词： Antarctica Zhongshan station surface energy balance turbulent exchange flux radiative flux.

Towards More Snow Days in Summer since 2001 at the Great Wall station,Antarctic Peninsula:The Role of the Amundsen Sea Low

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2020年第5期37卷 494-504页

作者： Minghu DING Wei HAN Tong ZHANG Xiaoyuan YUE Jeremy FYKE Ge LIU Cunde XIAO State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Fluid Dynamics and Solid Mechanics Group Los Alamos National LaboratoryLos AlamosNew Mexico 87545USA Associated Engineering Group LtdVernonBritish Columbia V1T 9P9Canada State Key Laboratory of Earth Surface and Resource Ecology Beijing Normal UniversityBeijing 100875China Beijing Meteorological Observation Center Beijing 100176China

The variation in the precipitation phase in polar regions represents an important indicator of climate change and variability.We studied the precipitation phase at the Great Wall station and Antarctic Peninsula(AP)region,based on daily precipitation,synoptic records and ERA-Interim data during the austral summers of 1985?2014.Overall,there was no trend in the total precipitation amount or days,but the phase of summer precipitation(rainfall days versus snowfall days)showed opposite trends before and after 2001 at the AP.The total summer rain days/snow days increased/decreased during 1985?2001 and significantly decreased at a rate of?14.13 d(10 yr)?1/increased at a rate of 14.31 d(10 yr)?1 during 2001?2014,agreeing well with corresponding variations in the surface air temperature.Further,we found that the longitudinal location of the Amundsen Sea low(ASL)should account for the change in the precipitation phase since 2001,as it has shown a westward drift after 2001[?41.1°(10 yr)?1],leading to stronger cold southerly winds,colder water vapor flux,and more snow over the AP region during summertime.This study points out a supplementary factor for the climate variation on the AP.

关键词： precipitation phase Great Wall station Amundsen Sea Low