Investigating variable stars in the open cluster NGC 1912 and its surrounding field     

李春燕  艾力·伊沙木丁  张余  宋芳芳  曾祥云  陈力  牛虎彪  白建银  刘军辉 《天文和天体物理学研究(英文版)》2021,(3):167-183

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   

The Effect of Hydraulic Gradient and Pattern of Conduit Systems on Tracing Tests: Bench-Scale Modeling     

Zargham Mohammadi  Mohammad Javad Gharaat  Malcolm Field 《Ground water》2019,57(1):110-125

Tracer breakthrough curves provide valuable information about the traced media, especially in inherently heterogeneous karst aquifers. In order to study the effect of variations in hydraulic gradient and conduit systems on breakthrough curves, a bench scale karst model was constructed. The bench scale karst model contains both matrix and a conduit. Eight tracing tests were conducted under a wide range of hydraulic gradients from 1 to greater than 5 for branchwork and network-conduit systems. Sampling points at varying distances from the injection point were utilized. Results demonstrate that mean tracer velocities, tracer mass recovery and linear rising slope of the breakthrough curves were directly controlled by hydraulic gradient. As hydraulic gradient increased, both one half the time for peak concentration and one fifth the time for peak concentration decreased. The results demonstrate the variations in one half the time for peak concentration and one fifth the time for peak concentration of the descending limb for different sampling points under differing hydraulic gradients are mainly controlled by the interactions of advection with dispersion. The results are discussed from three perspectives: different conduit systems, different hydraulic-gradient conditions, and different sampling points. The research confirmed the undeniable role of hydrogeological setting (i.e., hydraulic gradient and conduit system) on the shape of the breakthrough curve. The extracted parameters (mobile-fluid velocity, tracer-mass recovery, linear rising limb, one half the time for peak concentration, and one fifth the time for peak concentration) allow for differentiating hydrogeological settings and enhance interpretations the tracing tests in karst aquifers.  相似文献   

Spatial analysis of water quality and its suitability in farming giant freshwater prawn (Macrobrachium rosenbergii) in Negeri Sembilan region,Peninsular Malaysia     

Benjamin Ezekiel Bwadi  Firuza Begham Mustafa  Mohammad Lokman Ali  Subha Bhassu 《Singapore journal of tropical geography》2019,40(1):71-91

Finding potential sites for resilient prawn production in the tropical environment that also prevents wastage of natural resources is not an easy task. The purpose of this study is to evaluate water quality suitability for prawn farming in Negeri Sembilan of Peninsular Malaysia based on Geographic Information System (GIS). To achieve this goal, numerous criteria including sources of water, water temperature, water pH, sources of pollution, salinity, soil texture and availability of phytoplankton criteria were considered for the modelling process. Analytic Hierarchy Process (AHP) technique was performed to standardize the criteria and the weighting process. The weighted overlay of indicators and results were accomplished by applying the Multi‐Criteria Decision Analysis (MCDA) method in GIS. It was indicated that the Negeri Sembilan area has potential for prawn farming. The results showed that about 25 per cent (163 056.93 ha) of the area was most suitable for prawn farming, about 58 per cent (384 656.88 ha) was considered moderately suitable, while 18 per cent (117 633.49 ha) was regarded as least suitable. The study concluded that the multi‐criteria decision analysis of water quality for prawn farming is vital for regional economic planning in the Negeri Sembilan area and also significant when establishing a model for aquaculture development.  相似文献   

Makran ophiolitic basalts (SE Iran) record Late Cretaceous Neotethys plume-ridge interaction     

Rasoul Esmaeili  Mohammad Ebrahimi  Ji’En Zhang  Zhiyong Zhang  Yasser Abd El-Rahman 《International Geology Review》2020,62(13-14):1677-1697

ABSTRACT

The Makran complex in southeast Iran provides a spectacular subduction-related accretionary complex to understand the mechanism of oceanic accretion and the evolution of subduction zones. In this paper, we present new major and trace element data as well as isotopic compositions of mafic volcanic blocks from the Makran ophiolitic mélange complex (OMC). Our aim is to assess the genesis of these rocks and discuss their implications on the evolution of Neotethys Ocean. These volcanic blocks are composed mainly of basalts with minor trachytes. The Makran lavas are occasionally interlayered with tuff layers. Zircons from these tuffs give U-Pb ages of 95 Ma, which is well in accordance with the reposted microfossil data for the interlayered pelagic limestones with pillow lavas. Makran basalts can be geochemically subdivided into four groups; normal to transitional MORB, enriched-MORB, Plume-type MORB and alkaline (-OIB-like) basalts. The OIB-like pillow lavas are represented by high values of Th/Tb (6.3–7.4) which are higher than other basalts (group 1 = 0.3–0.8; groups 2 = 0.7–1.6; group 3 = 1.58–1.36).¹⁴³Nd/¹⁴⁴Nd_(t) ratios for basalts ranges from 0.51247 to 0.51292, whereas ⁸⁷Sr/⁸⁶Sr_(t) isotopic composition of the OMC lavas varies from 0.704433 to 0.709466. The Pb isotopic composition of the lavas are quite high, ranging from 15.49–15.66 for ²⁰⁷Pb/²⁰⁴Pb_(t), 18.09–19.12 for ²⁰⁶Pb/²⁰⁴Pb_(t) and 37.80–39.23 for ²⁰⁸Pb/²⁰⁴Pb_(t). The chemistry of these rocks suggests that they were formed most likely in an oceanic setting with clear plume-ridge interaction. These rocks can form from partial melting of a highly heterogeneous mantle source, which is extensively metasomatized with deep mantle OIB-type components. We suggest these rocks have been generated in an oceanic ridge with plume-ridge interaction, similar to the Iceland-Reykjanes Ridge, before being fragmented and accreted into the Makran accretionary complex.  相似文献   

Time–space fractional governing equations of transient groundwater flow in confined aquifers: Numerical investigation          下载免费PDF全文

Tongbi Tu  Ali Ercan  M. Levent Kavvas 《水文研究》2018,32(10):1406-1419

In order to model non‐Fickian transport behaviour in groundwater aquifers, various forms of the time–space fractional advection–dispersion equation have been developed and used by several researchers in the last decade. The solute transport in groundwater aquifers in fractional time–space takes place by means of an underlying groundwater flow field. However, the governing equations for such groundwater flow in fractional time–space are yet to be developed in a comprehensive framework. In this study, a finite difference numerical scheme based on Caputo fractional derivative is proposed to investigate the properties of a newly developed time–space fractional governing equations of transient groundwater flow in confined aquifers in terms of the time–space fractional mass conservation equation and the time–space fractional water flux equation. Here, we apply these time–space fractional governing equations numerically to transient groundwater flow in a confined aquifer for different boundary conditions to explore their behaviour in modelling groundwater flow in fractional time–space. The numerical results demonstrate that the proposed time–space fractional governing equation for groundwater flow in confined aquifers may provide a new perspective on modelling groundwater flow and on interpreting the dynamics of groundwater level fluctuations. Additionally, the numerical results may imply that the newly derived fractional groundwater governing equation may help explain the observed heavy‐tailed solute transport behaviour in groundwater flow by incorporating nonlocal or long‐range dependence of the underlying groundwater flow field.  相似文献   

Cluster Analysis of Petrophysical and Geological Parameters for Separating the Electrofacies of a Gas Carbonate Reservoir Sequence     

Abdideh  Mohammad  Ameri  Ayoub 《Natural Resources Research》2020,29(3):1843-1856

Natural Resources Research - Assessing reservoir properties and knowing the relationship between different reservoir parameters can significantly help to plan for production from a reservoir. In...  相似文献   

Detecting Land Subsidence Due to Groundwater Withdrawal in Aliabad Plain,Iran, Using ESA Sentinel-1 Satellite Data     

Edalat  Ali  Khodaparast  Mahdi  Rajabi  Ali M. 《Natural Resources Research》2020,29(3):1935-1950

Natural Resources Research - In the present study, ground subsidence in the Aliabad plain (central Iran) was investigated using differential synthetic aperture radar interferometry. The data used...  相似文献   

A Study on the Surface Wettability of Clastic Rocks with Potential Application for CO2 Storage Sites     

Umar  Bappah Adamu  Gholami  Raoof  Raza  Arshad  Downey  William Samuel  Sarmadivaleh  Mohammad  Shah  Afroz A.  Nayak  Prasanta 《Natural Resources Research》2020,29(3):2051-2061

Natural Resources Research - There have been many studies carried out in the past decades attempting to develop strategies for a safe injection of CO2 into storage sites without leakage and...  相似文献   

3D Structural,Facies and Petrophysical Modeling of C Member of Six Hills Formation,Komombo Basin,Upper Egypt     

Ali  Moamen  Abdelmaksoud  Ahmed  Essa  M. A.  Abdelhady  A.  Darwish  M. 《Natural Resources Research》2020,29(4):2575-2597

Natural Resources Research - Two main reservoirs are producing in Komombo Basin: the first one belongs to the C Member of the Six Hills Formation, and the second belongs to the Albian/Cenomanian...  相似文献   

3D Static Modeling and Petrographic Aspects of the Albian/Cenomanian Reservoir,Komombo Basin,Upper Egypt     

Ali  Moamen  Abdelhady  A.  Abdelmaksoud  Ahmed  Darwish  M.  Essa  M. A. 《Natural Resources Research》2020,29(2):1259-1281

Natural Resources Research - The Albian/Cenomanian reservoir is one of the two main reservoirs composing the petroleum system in the Komombo Basin. However, these reservoirs have not previously...  相似文献