分类： 天文学 >> 天文学 提交时间： 2017-10-11 合作期刊: 《天文研究与技术》
摘要： 为应对我国的宽视场地基广角相机阵在大数据管理和实时处理上带来的挑战，提出一种基于列存储数据库MonetDB的时序数据处理与管理系统设计方案。本方案充分利用MonetDB兼具数据处理和管理于一体的数据库平台特点，通过将交又认证等核心数据处理算法内嵌于数据库中，从而实现将“计算带到数据中”的设计理念。同时，对本方案开展了多项关键技术的研究与测试:TPC-H基准性能测试;大数据加载能力测试及优化研究;基于MonetDB的Zone算法实现与测试;可定制函数开发功能的测试。初步的预研结果表明，列存储切实可行，同时对本设计方案作详细的介绍。提出的基于列存储MonetDB数据库设计的海量星表数据处理应用方案，是高效的数据处理与管理为一体的天文数据库解决方案。
分类： 物理学 >> 核物理学 提交时间： 2016-08-31
Ying Zhang
Jing Huang
Ding Chen
Liu-Ming Zhai
Xu Chen
Xiao-Bin Hu
Yu-Hui Lin
Hong-Bo Jin
Xue-Yao Zhang
Cun-Feng Feng: Huan-Yu Jia
Xun-Xiu Zhou
DANZENGLUOBU
Tian-Lu Chen
LABACIREN
Mao-Yuan Liu
Qi Gao
ZHAXICIREN
摘要： A new hybrid experiment has been constructed to measure the chemical composition of cosmic rays around the "knee" in the wide energy range by the Tibet ASγ collaboration at Tibet, China, since 2014. They consist of a high-energy air-shower-core array (YAC-II), a high-density air-shower array (Tibet-III) and a large underground water-Cherenkov muon-detector array (MD). In order to obtain the primary proton, helium and iron spectra and their "knee" positions in the energy range lower than 1016 eV, each of PMTs equipped to the MD cell is required to measure the number of photons capable of covering a wide dynamic range of 100 - 106 photoelectrons (PEs) according to Monte Carlo simulations. In this paper, we firstly compare the characteristic features between R5912-PMT made by Japan Hamamatsu and CR365-PMT made by Beijing Hamamatsu. This is the first comparison between R5912-PMT and CR365-PMT. If there exists no serious difference, we will then add two 8-inch-in-diameter PMTs to meet our requirements in each MD cell, which are responsible for the range of 100 - 10000 PEs and 2000 - 1000000 PEs, respectively. That is, MD cell is expected to be able to measure the number of muons over 6 orders of magnitude.
分类： 物理学 >> 核物理学 提交时间： 2016-08-31
摘要： A new air-shower core-detector array (YAC : Yangbajing Air-shower Core-detector array) has been developed to measure the primary cosmic-ray composition at the "knee" energies in Tibet, China, focusing mainly on the light components. The prototype experiment (YAC-I) consisting of 16 detectors has been constructed and operated at Yangbajing (4300 m a.s.l.) in Tibet since May 2009. YAC-I is installed in the Tibet-III AS array and operates together. In this paper, we performed a Monte Carlo simulation to check the sensitivity of YAC-I+Tibet-III array to the cosmic-ray light component of cosmic rays around the knee energies, taking account of the observation conditions of actual YAC-I+Tibet-III array. The selection of light component from others was made by use of an artificial neural network (ANN). The simulation shows that the light-component spectrum estimated by our methods can well reproduce the input ones within 10\% error, and there will be about 30\% systematic errors mostly induced by the primary and interaction models used. It is found that the full-scale YAC and the Tibet-III array is powerful to study the cosmic-ray composition, in particular, to obtain the energy spectra of protons and helium nuclei around the knee energies.
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