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1.
In this work,we studied the variable stars in the open cluster NGC 1912 based on the photometric observations and Gaia DR2 data.More than 3600 CCD frames in B,V,R filters were reduced,and we obtained the light curves that span about 63 hours.By analyzing these light curves,we detected 24 variable stars,including 16 periodic variable stars,seven eclipsing binaries and one star whose type is unclear.Among these 24 variable stars,11 are newly discovered,which are classified as sixγDoradus stars,oneδScuti star,three detached binaries and one contact binary.We also confirmed 13 previously known variable stars.Based on cluster members identified by Cantat-Gaudin et al.(2018),we inferred cluster memberships for these detected variable stars.Using Gaia DR2 data,we plotted a new color-magnitude diagram for NGC1912,and showed the nature of variable cluster members in kinematical properties and heliocentric distance.Among the 24 variable stars,seven variables are probable cluster members,which show homogeneity in kinematic characters and space position with the established cluster members.Four of the seven variable cluster members are the previously discovered stars,consisting of twoγDor stars and twoδSct stars.The remaining three variable cluster members,which are allγDor stars,are firstly detected in this work.The main physical parameters of these variable cluster members estimated from the color-magnitude diagram are log(age/yr)=8.75,[Fe/H]=-0.1,m-M=10.03 mag,and E(B-V)=0.307. 相似文献
2.
Zhifan Mu Tianxiao Li Dong Liu Qiang Fu Renjie Hou Qinglin Li Yi Ji Song Cui Mo Li 《水文研究》2021,35(4):e14155
To enhance the utilization efficiency of farmland irrigation water and reduce the leakage of water conveyance channels, the leakage process of channels was simulated dynamically. The simulated results were compared with data measured in laboratory experiments, and the performance of the model was evaluated. The results indicated that the simulated values of the model were consistent with the observation values, and the R2 values varied between 0.91 and 0.99. In addition, based on the laboratory experiments, a water supply system (Mariotte bottles) and soil box were built using plexiglass. Three influencing factors, namely, the channel form, soil texture and channel cross-sectional area, were varied to observe and calculate the resulting cumulative infiltration amount, infiltration rate and wetting front migration distance. HYDRUS-3D software was used to solve the three-dimensional soil water movement equation under different initial conditions. The results demonstrated that the U-shaped channel was more effective than the trapezoidal channel in increasing the utilization efficiency of the water resources. A U-shaped channel with a small channel cross-sectional area should be adopted and the soil particle size should be prioritized in the construction of water conveyance channels for farmlands. The simulation results were in agreement with the observed results, which indicates that HYDRUS-3D is a reliable tool that can accurately simulate the soil moisture movement in water conveyance channels. The research results can provide a reference for the design and operation of farmland irrigation systems. 相似文献
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Song Jun Young Sim Youngjong Jang Jaewon Hong Won-Taek Yun Tae Sup 《Acta Geotechnica》2020,15(7):1967-1980
Acta Geotechnica - To resolve the environmental and sustainability issues from fugitive dust emission and conventional mitigation methods, multiple experiments were conducted to evaluate the... 相似文献
5.
Xuechao Wu Qingzhen Hao B Marković Slobodan Yu Fu Namira Yang Song Zhengtang Guo 《地球科学进展》2020,35(4):363-377
Danube loess, located at the westernmost part of the widespread Eurasian loess belt, is one of the most well-preserved aeolian dust deposits in Europe with the basal age dating back over 1 Ma. Owing to its unique location and formation processes, Danube loess plays an important role in understanding the linkage of climate changes in different climate regimes over Eurasian continent and paleoclimatic changes in middle-high northern latitudes. Major research advances of the Danube loess, including compositions, provenance, chronology, stratigraphy and paleoenvironment changes were systematically reviewed and the focuses of future research were suggested. To better understand loess provenance, the compositions of sediments in all the potential source areas should be investigated, and methodological study of provenance indicators and application of multi-proxies approaches need to be carried out. Chronologically and stratigraphically, feldspar luminescence dating and tephrochronology methods should be widely used, and the establishment of a uniform stratigraphic framework and correlation scheme should be constrained by precise chronology. In terms of the paleoenvironment, it is necessary to conduct high-resolution multi-proxies reconstruction of paleoenviroment for the entire loess-paleosol sequence, extending from the last interglacial period (130 ka to present) to interval of last 1 Ma. The future progress in Danube loess is crucial to improving the study of continental paleoclimate comparison and paleoclimate dynamics over the Eurasian loess region. 相似文献
6.
70年来中国化学海洋学研究的主要进展 总被引:5,自引:3,他引:2
我国的海洋化学工作者通过70年来,特别是近30年来的化学海洋学研究,实现了我国与世界先进水平进入同步发展的快车道,其显著的特点是:(1)化学海洋学研究从元素地球化学分布系统转向了以揭示深层次海洋生物地球化学过程为核心的研究;(2)化学海洋学研究实现了多领域、多视点的综合交叉研究;(3)更加关注了人为影响与自然变化共同作用下的海洋生态环境变化研究,对近海和海岸带而言,更加注重从海陆统筹一体化角度探析化学物质的分布迁移特征。本文从生源要素的海洋生物地球化学过程、微/痕量元素与同位素的海洋化学研究、生物过程作用下的化学海洋学过程等角度,重点总结归纳和分析了30年来我国海洋化学研究的重要进展和发展状况,以期对化学海洋学的进一步研究提供借鉴和启迪。 相似文献
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文中利用加拿大环境部气候研究中心研发的惩罚最大t检验方法,选取均一的邻近气象站为参考站,结合元数据信息,对1960-2017年成山头海洋站海表温度序列进行了均一性检验与订正。利用订正后的海表温度序列对成山头海温气候变化特征进行分析。结果表明,订正前后年平均海表温度趋势发生了明显改变,表现出海温上升趋势较订正前加强的特征,增暖趋势由订正前的0.04℃/10 a上升到0.15℃/10 a,其中最暖的5个年份多发生在1980年以后,分别为1973年、1989年、2002年、2007年和2017年。海表温度总体呈显著上升趋势和明显的年代际波动,20世纪60年代至80年代末为偏冷阶段,之后开始增暖,20世纪90年代至今为偏暖阶段。1960-2017年,成山头的海温突变点在1987年,是一次增暖性突变,与中国大陆的气温突变特征和气温变化阶段性特征非常一致。 相似文献
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Journal of Oceanology and Limnology - Microcystins (MCs) are cyclic hepatotoxic peptides produced by the bloom-forming cyanobacterium Microcystis and present a public health hazard to humans and... 相似文献
10.
海南省连片贫困地区农户致贫风险分析 总被引:4,自引:1,他引:3
农村贫困与减贫是世界性难题,也是中国各级政府高度重视并着力解决的重大民生问题。基于农户及致贫风险的文献梳理,从区位、社会和劳动力3个要素维度构建了农户致贫风险分析的二元Logistic回归模型。采用484户农户问卷调查数据,分析了海南省连片贫困地区农户的致贫风险,提出有效减贫和持续发展对策。研究发现:① 海南连片贫困地区生态环境良好但贫困发生率较高,家庭劳动力较充裕但受教育水平较低,子女教育支出负担重,因病因残致贫比例较高,女性务工人口较多,农户自身脱贫致富的发展动力不足。② 海拔高度200 m以下、男性户主、拥有残疾或患病成员、务工人口比例低、女性务工人员占比高、以及单位劳动力供养学生数高的农户具有更大的致贫风险。③ 研究未发现女性户主、少数民族、低受教育水平户主、大型规模家庭有更高的致贫风险,女性成员比例、抚养比等因素对农户贫困影响较小。激发农户内生动力、大力发展特色化和规模化农业、增加农户就业机会、加强针对农民工、女性务工人员和病残群体的社会保障等减贫政策制定实施是实现脱贫攻坚目标的重要途径。 相似文献