Analysis of subdiffusion in disordered and fractured media using a Grünwald-Letnikov fractional calculus model     

Abiola D. Obembe  Sidqi A. Abu-Khamsin  M. Enamul Hossain  Kassem Mustapha 《Computational Geosciences》2018,22(5):1231-1250

The increasing applications of fractional calculus in simulating the anomalous transport behavior in disordered and fractured heterogeneous porous media has grown rapidly over the past decade. In the present study, a temporal fractional flux relationship is employed as a constitutive equation to relate the volumetric flow rate to the gradient of the pore pressure. The novelty of this paper entails interpreting the time fractional derivative operator in the flux relationship by the Grünwald-Letnikov (G-L) definition as opposed to the Caputo interpretation which has been widely considered. Subsequently, a numerical scheme based on the block-centered finite-difference discretization is formulated to handle the resulting non-linear fractional diffusion model. In addition, a linear stability analysis is successfully performed to establish the stability criterion of the developed numerical scheme. An expression for the modified incremental material balance index was derived to assess the effectiveness of the numerical discretization process. Finally, numerical experiments were performed to provide qualitative insights into the nature of pressure evolution in a hydrocarbon reservoir under the influence subdiffusion. In summary, the results establish that subdiffusion regime results in the development of higher pressure drop in the reservoir. This paper will provide a strong foundation for researchers interested in investigating anomalous diffusion phenomena in porous media.  相似文献   

Spatial variability of climatic hazards in Bangladesh     

Chowdhury  Md. Arif  Zzaman  Rashed Uz  Tarin  Nusrat Jahan  Hossain  Mohammad Jobayer 《Natural Hazards》2022,110(3):2329-2351

Natural Hazards - Climate change is evident with the extreme climatic indices changing all over the world. Bangladesh is one of the most vulnerable countries to climate change. The patterns of...  相似文献   

Comment on “Electrostatic compressive and rarefactive shocks and solitons in relativistic plasmas occurring in polar regions of pulsar”     

M. G. Hafez  M. R. Talukder  M. Hossain Ali 《Astrophysics and Space Science》2016,361(5):154

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Memory persistency and nonlinearity in daily mean dew point across India     

Rajdeep Ray  Mofazzal Hossain Khondekar  Koushik Ghosh  Anup Kumar Bhattacharjee 《Theoretical and Applied Climatology》2016,124(1-2):119-128

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Is correlation dimension a reliable proxy for the number of dominant influencing variables for modeling risk of arsenic contamination in groundwater?     

Jason Hill  Faisal Hossain  Bellie Sivakumar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(1):47-55

The correlation dimension (CD) of a time series provides information on the number of dominant variables present in the evolution of the underlying system dynamics. In this study, we explore, using logistic regression (LR), possible physical connections between the CD and the mathematical modeling of risk of arsenic contamination in groundwater. Our database comprises a large-scale arsenic survey conducted in Bangladesh. Following the recommendation by Hossain and Sivakumar (Stoch Environ Res Risk Assess 20(1–2):66–76, 2006), who reported CD values ranging from 8 to 11 for this database, 11 variables are considered herein as indicators of the aquifer’s geochemical regime with potential influence on the arsenic concentration in groundwater. A total of 2,048 possible combinations of influencing variables are considered as candidate LR risk models to delineate the impact of the number of variables on the prediction accuracy of the model. We find that the uncertainty associated with prediction of wells as safe and unsafe by LR risk model declines systematically as the total number of influencing variables increases from 7 to 11. The sensitivity of the mean predictive performance also increases noticeably for this range. The consistent reduction in predictive uncertainty coupled with the increased sensitivity of the mean predictive behavior within the universal sample space exemplify the ability of CD to function as a proxy for the number of dominant influencing variables. Such a rapid proxy, based on non-linear dynamic concepts, appears to have considerable merit for application in current management strategies on arsenic contamination in developing countries, where both time and resources are very limited.  相似文献   

Intra‐ and interannual export of nitrogen and phosphorus in the subtropical Richmond River catchment,Australia     

Lester McKee  Bradley Eyre  Shahadat Hossain 《水文研究》2000,14(10):1787-1809

Nitrogen and phosphorus concentrations were measured and exports were calculated in the subtropical Richmond River catchment between July 1994 and June 1996. A stratified sampling approach was adopted owing to the extreme and rapid changes in riverine discharge, which varied by up to 10 000 times over the study period. Nutrient concentrations were lowest during baseflow. During storm discharge, dissolve inorganic and organic and particulate nitrogen and phosphorus concentrations increased two‐ to five fold, and followed hysteresis patterns that were attributed to the integration and/or depletion of catchment nutrient sources during an event. Dissolved organic nitrogen and particulate phosphorus were the dominant nutrient forms. Land use and antecedent conditions had a large influence on nutrient concentrations and exports. During the 1995–96 year (slightly above the mean annual discharge) 96% of nitrogen and 98% of phosphorus loads were transported in less than 6% of the time. When averaged across the catchment, monthly riverine nutrient loads varied by up to 1061‐fold during the study and exports were approximately four‐fold greater during the second year relative to the first. The subtropical Richmond River catchment has greater intra‐ and potential interannual variability in nutrient loads and exports when compared with temperate catchments from other parts of the world. It is suggested that in tropical and subtropical Australian catchments with large intra‐ and interannual variation in discharge, the need for parameterizing the antecedent conditions, such as the degree of nutrient storage, may make it difficult to model spatial and temporal (short time‐scale) nutrient exports. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Planar and nonplanar quantum dust ion-acoustic Gardner double layers in multi-ion dusty plasma     

M. Hasan  M. M. Hossain  A. A. Mamun 《Astrophysics and Space Science》2013,344(1):113-118

The longitudinal fast solitary waves induced by weakly relativistic positron showers of astrophysical origin are studied in a plasma system contaminated with some massive impurities in presence of superthermal effects. The superthermal effects are due to the high energy electrons. The impurities are dust corpuscles with positive and negative charges. It is noticed that increase in the kappa parameter of electrons and relativistic streaming factor of weakly relativistic positron shower, negative dust concentration invoke an enhancement in the strength of solitary wave. On the other hand increase in the shower’s temperature as well as positive dust concentration diminish the solitary hump strength. It is worth to mention that only hump type compressive fast solitary waves are predicted by our model, for the given set of plasma parameters, because the convective coefficient of the nonlinear governing equation for solitary wave remains positive in considered regime of interaction for plasma and positron shower. Our calculations in linear regime predict both the fast and slow positron shower induced longitudinal, electrostatic perturbations. Our results may be of importance in understanding the nonlinear propagation of waves in doped astrophysical superthermal plasmas with relativistic positron showers.  相似文献   

A comparative study of the ATC-40 recommended and numerically derived M-φ relationship     

Sifat Sharmeen Muin  Tahsin Reza Hossain 《地震工程与工程振动(英文版)》2011,10(4):547-552

Nonlinear static analysis procedures are key tools in evaluating the performance of existing buildings and verifying the design of seismic retrofits in seismically active regions. In this procedure, nonlinear force-displacement or moment-curvature (M-φ) behavior needs to be defined. In the ATC-40 document, values of M-φ have been proposed to model elements in a nonlinear procedure. However, these values need to be investigated to determine if they are representative of actual values. In this paper, an attempt has been made to numerically derive M-φ curves to simulate actual performance. Then, these curves are compared with the ATC-40 recommended curves with respect to various parameters. The study indicated that ATC-40 suggested values are conservative in nature in most situations.  相似文献   

Potential ecological risk assessment of heavy metal contamination in sediment and water body around Dhaka export processing zone,Bangladesh   总被引：3，自引：2，他引：1  

M. Safiur Rahman  Narottam Saha  A. Hossain Molla 《Environmental Earth Sciences》2014,71(5):2293-2308

Sediments and surface water contamination by the industrial effluents containing heavy metals is the most detrimental environmental impact. Therefore, the present work attempts to determine the status of eight heavy metal distribution in sediments and water samples, and their ecological risks’ assessment in the studied area. The distribution pattern of heavy metals in the water and sediment follows the sequences: Zn > Cu > Pb > Cr > Mn > Ni > As > Cd and Mn > Zn > Cr > Pb > Cu > Ni > As > Cd, respectively. Gross water pollution is observed at different sampling points of Dhalai Beel and Bangshi River. The comparison of sedimentary mean metal concentrations with several environmental contamination monitoring parameters, viz, threshold effect level (TEL), probable effect level (PEL), and severe effect lever (SEL) indicates that the metal levels are less than PEL except Cr. Moreover, the level of contamination degree (C _d) and modified degree of contamination (mC _d) indicates ‘low’ and ‘nil to low’ degree of contamination, respectively. Pollution load indices (PLI) of the studied area are lower than unity, indicates no pollution. Furthermore, a toxic-response factor is applied to assess the potential ecological risk of these heavy metals into the water body. The results of this study exhibit a low potential ecological risk of heavy metals. The Pearson’s correlation and cluster analysis are also performed to assess the heavy metal interactions in water and sediment samples.  相似文献   

Delineation using geophysical data of the hydrocarbon bearing zone in the Begumganj structure, Hatia Trough, southern Bengal Basin, Bangladesh     

Rashed Abdullah  Delwar Hossain  M. Rafiqul Alam 《Journal of the Geological Society of India》2013,82(3):271-276

The Begumganj structure of the Hatia Trough in Bengal Basin has proved it’s hydrocarbon potentiality. Several seismic sections have been analyzed to construct different maps and to interpret subsurface geology, structure and stratigraphy. These maps reveal that the Begumganj structure is an elongated to oval shaped asymmetrical anticline having the general trend NNW-SSE. No major faults affecting the structure could have been identified. Most of the reflectors are strongly affected by channels, especially at the western flank. Based on the analysis of seismic and available well data, the only gas bearing strata at depth of 2995 m (or TWT 2.02 seconds) has been identified. The structure is interpreted as a strati-structure entrapment because shale fill channel truncated this layer on western flank and at the crestal part of the anticline. The structure probably formed after the deposition of sediments. The channel has formed after the corresponding unit cut has been deposited. The channels eroding the reservoir unit range from Late Miocene to Early Pliocene age where the anticline probably begun to form during the Pliocene. Strong increase in amplitude (bright spot), possibly associated with hydrocarbon, has been apparent on seismic lines BG 9 and BG 10. The stratigraphic succession based on the information of the wells drilled on this structure and it’s surrounding fields reveals that the lithological sequences range from Miocene to Recent age where the only proven gas producing sand zone is located in the Bhuban Formation.  相似文献