Plane symmetric gravitational collapse and linear equation of state     

M. Sharif  Amal Majid 《Astrophysics and Space Science》2013,347(1):71-76

This paper examines the gravitational collapse in plane symmetry with a perfect fluid using a linear equation of state p=kρ. We find a class of collapse models satisfying the Einstein field equations and also the regularity as well as energy conditions. For a given initial data, the outcome of the collapse turns out to be a black membrane or a naked singularity depending upon the equation of state parameter. We conclude that this parameter plays a crucial role in determining the final fate of the collapse.  相似文献   

Genesis and diagenetic evolution of Habo formation,Kachchh, Gujarat     

A. H. M. Ahmad  A. Majid 《Journal of the Geological Society of India》2010,76(4):331-344

The Kachchh Basin is a pericratonic rift basin situated at the western margin of the Indian plate. The Habo Dome embodies an important exposure of Bathonian to Kimmergian sediments among the Kachchh Mainland exposures. Based on vertical facies transitions, facies associations were documented: mixed shallow marine (Facies association 1), shoreface and lagoon deposits (Facies association II) and subtidal innershelf below fair weather wave base (Facies association III). The documented facies associations reflect that Habo Dome sediments deposited in a variety of environments from shallow marine to fluvio-deltaic and were strongly influenced by fluctuation of relative sea level. The dominance of floating grains and point contacts in the sandstone indicate that detrital grains do not show much pressure effects as a result of either shallow burial or early cementation. The sandstones were cemented by iron oxide, carbonate and silica in order of abundance. Three types of cements, blocky, rim and fibrous cement occur in the studied limestone representing phreatic, fresh water phreatic and deep burial diagenetic stages. Neomorphism and micritization are common. Both primary and secondary porosity exists in these sediments. Different graphs of porosity versus depth suggest a depth of burial in the range of 615–769 m.  相似文献   

Robust strategies for climate change adaptation in the agricultural sector under deep climate uncertainty     

Abbasi  Hamid  Delavar  Majid  Bigdeli Nalbandan  Roya  Hashemy Shahdany  Mehdy 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(6):755-774

Stochastic Environmental Research and Risk Assessment - Adaptive planning in climate change condition is a significant challenge for effective management of water resources and agricultural...  相似文献   

Water quality variations in different climates of Iran: toward modeling total dissolved solid using soft computing techniques     

Majid?Montaseri  Sarvin?Zaman Zad GhavidelEmail author  Hadi?Sanikhani 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(8):2253-2273

In present paper, wavelet analysis of total dissolved solid that monitored at Nazlu Chay (northwest of Iran), Tajan (north of Iran), Zayandeh Rud (central of Iran) and Helleh (south of Iran) basins with various climatic conditions, have been studied. Daubechies wavelet at suitable level (db4) has been calculated for TDS of each selected basins. The performance of artificial neural networks (ANN), two different adaptive-neurofuzzy inference system (ANFIS) including ANFIS with grid partition (ANFIS-GP) and ANFIS with subtractive clustering (ANFIS-SC), gene expression programming (GEP), wavelet-ANN, wavelet-ANFIS and wavelet-GEP in predicting TDS of mentioned basins were assessed over a period of 20 years at twelve different hydrometric stations. EC (μmhos/cm), Na (meq L^?1) and Cl (meq L^?1) parameters were selected (based on Pearson correlation) as input variables to forecast amount of TDS in four studied basins. To develop hybrid wavelet-AI models, the original observed data series was decomposed into sub-time series using Daubechies wavelets at suitable level for each basin. Based on the statistical criteria of correlation coefficient (R), root mean square error (RMSE) and mean absolute error (MAE), the hybrid wavelet-AI models performance were better than single AI models in all basins. A comparison was made between these artificial intelligence approaches which emphasized the superiority of wavelet-GEP over the other intelligent models with amount of RMSE 18.978, 6.774, 9.639 and 318.363 mg/l, in Nazlu Chay, Tajan, Zayandeh Rud and Helleh basins, respectively.  相似文献   

Geophysical Investigation of Fresh‐Saline Water Interface: A Case Study from South Punjab,Pakistan          下载免费PDF全文

Muhammad Hasan  Yanjun Shang  Gulraiz Akhter  Majid Khan 《Ground water》2017,55(6):841-856

The importance of the study of fresh‐saline water incursion cannot be over‐emphasized. Borehole techniques have been widely used, but they are quite expensive, intrusive, and time consuming. The electrical resistivity method has proved very successful in groundwater assessment. This advanced technique uses the calculation of Dar‐Zarrouk (D‐Z) parameters, namely longitudinal unit conductance, transverse unit resistance, and longitudinal resistivity has been employed by using 50 vertical electrical sounding points to assess the groundwater and delineate the fresh‐saline water interface over 1045 km² area of Khanewal in Southern Punjab of Pakistan. The x‐y plots and maps of D‐Z parameters were produced to establish a decipherable vision for the occurrence and distribution of different water‐bearing formations of fresh‐saline water aquifers through a complicated situation of intermixing of different resistivity ranges for fresh‐saline water bodies. This technique is useful to reduce the ambiguity produced by the process of equivalence and suppression which cause intermixing in differentiating fresh, brackish, and saline aquifers during interpretation. The fresh‐saline water interface is correlated very well with the previous studies of water quality analysis carried out in Khanewal area. The results suggest that the D‐Z parameters are useful for demarcating different aquifer zones. The behavior and pattern of D‐Z parameters with respect to occurrence and distribution of different water‐bearing formations were effectively identified and delineated in the study area.  相似文献   

Prediction of the effect of water supplying from Shirindare dam on the Bojnourd aquifer using MODFLOW2000     

Hossein Mohammadzadeh  Majid Altafi Dadgar  Hamidreza Nassery 《Water Resources》2017,44(2):216-225

In recent years, the water demand has been increasing considerably in Bojnourd, capital of Northern Khorasan province in NE of Iran, and the extracted water from Bojnourd alluvial aquifer, with an area of 65 km², is not sufficient for residents. The required water is going to be supplied from Shirindare dam, located out of Bojnourd aquifer’s catchment area; therefore, the groundwater levels will rise in some parts of the aquifer, due to the return flow of supplied water, which will cause serious problems for the city. In this paper, the groundwater flow system of Bojnourd aquifer has been numerically simulated using MODFLOW code in GMS interface. The model, primarily, was calibrated for a steady state condition for the mean values of oneyear period (Sep. 2009 to Sep. 2010) which has a steady condition with low stresses on the aquifer. Then the model was run/calibrated for transient conditions for a two year period (Sep. 2007 to Sep. 2009). After determining the hydraulic properties of the aquifer and confirming their validity, different management scenarios, were applied to the model. Results reveal that groundwater levels in the urban area will rise by over 3 m, by infiltrating 40% of supplied water from the Shirindare dam into the aquifer. To manage the rising water levels, two different management scenarios were applied to the aquifer model. In doing so and with proper management of aquifer exploitation during critical situations, not only will the groundwater level drop; also the city of Bojnourd can develop urban landscaping by constructing sports/cultural camping area using the extra pumped water.  相似文献   

Apatite U–Pb geochronology and whole rock,Sr–Nd–Pb isotopic geochemistry of XV mafic-ultramafic intrusion,Bafq, Central Iran: Implications for petrogenesis and tectonic setting     

Sakine Amraei  Mohammad Yazdi  Liang Qiu  Chang-Zhi Wu  Lei Chen  Bertrand Moine  Majid Ghasemi Siani  Qihui Zhang  Shahrokh Rajabpour 《Island Arc》2024,33(1):e12514

The XV mafic-ultramafic intrusion is located in the western part of the Posht-e-Badam Block (PBB) within the Central Iranian Micro-Continent (CIMC). Petrographically, the intrusion is composed of gabbro and pyroxenite. Apatite U–Pb dating has established the crystallization age of this intrusion to be 363 ± 67 Ma. The XV intrusive rocks are tholeiitic to slightly calc-alkaline in nature and are characterized by an enrichment of large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE) and Heavy Rare Earth Elements (HREE), respectively. The major oxide elements display continuous trends relative to SiO₂. The ⁸⁷Sr/⁸⁶Sr(i) ratios range from 0.7045 to 0.7056, and the εNd(i) values range from 2.63 to 3.30. In addition, the ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb ratios exhibit a narrow range, varying from 18.68 to 18.70, 15.67 to 15.71, and 38.84 to 38.99, respectively. The geochemical and isotopic characteristics suggest that the parental magma was derived from a Sub- Continental Lithospheric Mantle (SCLM) that was modified by oceanic slab-derived components. The locations of the XV intrusive rocks in εNd(i) versus TDM (Ga) and Nb/La versus discrimination diagrams further support this conclusion. Fractional crystallization is identified as the dominant process influencing the formation of distinct lithological units within the XV intrusive rocks. Our newly presented isotopic and geochronological data, when considered in the regional context, suggest that the XV intrusive rocks were formed in an extensional tectonic setting. In this scenario, upwelling from the asthenospheric mantle induced heating, leading to the melting of previously subduction-modified SCLM. Comparative analysis with previously published ages indicates that extensional magmatism in the PBB continued into the Middle Paleozoic.  相似文献