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Assessment of physicochemical properties of water and their seasonal variation in an urban river in Bangladesh

Water Science and Engineering 2021年第2期14卷 139-148页

作者： Arafat rahman Ishrat Jahanara Yeasmin Nahar Jolly Department of Soil Water and EnvironmentUniversity of DhakaDhaka 1000Bangladesh Atmospheric and Environmental Chemistry Laboratory Chemistry DivisionAtomic Energy CentreDhaka 1000Bangladesh

To assess the magnitude of water quality decline in the Turag River of Bangladesh,this study examined the seasonal variation of physi-cochemical parameters of water,identified potential pollution sources,and clustered the monitoring months with similar *** samples were collected in four distinct seasons to evaluate temperature,pH,dissolved oxygen(DO)concentration,five-day biochemical oxygen demand(BOD 5),chemical oxygen demand(COD),electrical conductivity(EC),chloride ion(Cl^(-))concentration,total alkalinity(TA),turbidity,total dissolved solids(TDS)concentration,total suspended solids(TSS)concentration,and total hardness(TH)using standard *** analytical results revealed that 40%of water quality indices were within the permissible limits suggested by different agencies,with the exception of EC,Cl^(-)concentration,TA,turbidity,DO concentration,BOD 5,and COD in all *** analyses indicated that 52%of the contrasts were significantly different at a 95%confidence *** factor analysis presented the best fit among the parameters,with four factors explaining 94.29%of the total ***,BOD 5,COD,EC,turbidity,DO,and Cl?were mainly responsible for pollution loading and were caused by the significant amount of industrial discharge and toxicological *** cluster analysis showed the seasonal change in surface water quality,which is usually an indicator of pollution from rainfall or other ***,the values of different physico-chemical properties varied with seasons,and the highest values of pollutants were recorded in the *** the change in seasonal tem-perature and increase in rainfall,the seasonal Turag River water followed a self-refining trend as follows:rainy season>pre-winter>summer>winter.

关键词： Seasonal variation Physicochemical parameter Water quality Factor analysis Cluster analysis Turag River

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Nanoparticle-stabilized CO2 foam flooding for enhanced heavy oil recovery: A micro-optical analysis

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Petroleum 2024年第4期10卷 696-704页

作者： Arifur rahman Ezeddin Shirif Farshid Torabi Petroleum Systems Engineering Faculty of Engineering and Applied Science University of Regina Petroleum and Mining Engineering School of Applied Science & Technology Shahjalal University of Science and Technology

Surfactant flooding is a well-known chemical approach for enhancing oil recovery. Surfactant flooding has the disadvantage that it cannot withstand the harsh reservoir conditions. Improvements in oil recovery and release are made possible by the use of nanoparticles and surfactants and CO2co-injection because they generate stable foam, reduce the interfacial tension（IFT） between water and oil, cause emulsions to spontaneously form, change the wettability of porous media, and change the characteristics of flow. In the current work, the simultaneous injection of SiO2, Al2O3nanoparticles, anionic surfactant SDS, and CO2in various scenarios were evaluated to determine the microscopic and macroscopic efficacy of heavy oil recovery. IFT（interfacial tension） was reduced by 44% when the nanoparticles and SDS（2000 ppm） were added, compared to a reduction of roughly 57% with SDS only. SDS-stabilized CO2foam flooding, however, is unstable due to the adsorption of SDS in the rock surfaces as well as in heavy oil. To assess foam's potential to shift CO2from the high permeability zone（the thief zone） into the low permeability zone, directly visualizing micromodel flooding was successfully executed（upswept oil-rich zone）. Based on typical reservoir permeability fluctuations, the permeability contrast（defined as the ratio of high permeability to low permeability） for the micromodel flooding was selected. However, the results of the experiment demonstrated that by utilizing SDS and nanoparticles, minimal IFT was reached. The addition of nanoparticles to surfactant solutions, however, greatly boosted oil recovery,according to the findings of flooding studies. The ultimate oil recovery was generally improved more by the anionic surfactant（SDS） solution including nanoparticles than by the anionic surfactant（SDS） alone.

关键词： Micromodel CO 2 foam Surfactant Nanoparticles Interfacial tension Heavy oil

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Dynamics of Communal Land Degradation and Its Implications in the Arid Mountains of Pakistan:A Study of District Karak, Khyber Pakhtunkuwa

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Journal of Mountain Science 2014年第2期11卷 485-495页

作者： Iffat TABASSUM Fazlur rahman Fazlul HAQ Institute of Geography Urban & Regional Planning University of Peshawar

Similar to other areas of Pakistan, land resources in Khyber Pakhtunkhwa(KP) is kept under various ownership regimes for socio-economic and ecological benefits. For the last three to four decades, communal lands and resources are subjected to high rate of degradation and deterioration, which is leading to multifarious socio-economical and ecological implications. This paper intends to look into factors that are responsible for the degradation of communal land and the adaptability of the management mechanisms developed by the local inhabitants to conserve these resources. Moreover, this study also explores the sustainability of these adopted strategies in present circumstances. Data regarding socio-economic parameters of the inhabitants and their interactions with communal lands were collected through questionnaire cum interview method. As long-term climatic data for the area do not exist therefore focus group discussions were conducted to document the changing trend in rainfall regimes and temperature variations for the last about four decades. Results indicate that communal lands are highly vulnerable to degradation due to biophysical and anthropogenic factors. Local inhabitants have developed suitable measures to control the situation, however, accelerated socioeconomic transformations in the area have weakened the role of local institutions and that led to further degradation of these resources. Nevertheless, a number of locally formulated rules have been revived and implemented and it is hoped that these threatened resources would be conserved.

关键词： Communal lands Land degradation Climatic variability Adopted strategies Dry areas

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An extended J-integral for evaluating fluid-driven cracks in hydraulic fracturing

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第5期10卷 832-843页

作者： Huifang Song Sheik S.rahman School of Petroleum Engineering University of New South Wales

J-integral has served as a powerful tool in characterizing crack tip status. The main feature, i.e. path- independence, makes it one of the foremost fracture parameters. In order to remain the path- independence for fluid-driven cracks, J-integral is revised. In this paper, we present an extended J-in- tegral explicitly for fluid-driven cracks, e.g. hydraulically induced fractures in petroleum reservoirs, for three-dimensional （3D） problems. Particularly, point-wise 3D extended J-integral is proposed to char- acterize the state of a point along crack front. Besides, applications of the extended J-integral to porous media and thermally induced stress conditions are explored. Numerical results show that the extended J- integral is indeed path-independent, and they are in good agreement with those of equivalent domain integral under linear elastic and elastoplastic conditions. In addition, two distance-independent circular integrals in the K-dominance zone are established, which can be used to calculate the stress intensity factor （SIF）.

关键词： Extended J-integral Three-dimensional (3D) point-wise J-integral Crack tip behavior Hydraulic fracturing Path-independence

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Generalized Second Law of Thermodynamics in Wormhole Geometry with Logarithmic Correction

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Chinese Physics Letters 2011年第7期28卷 55-58页

作者： Faiz-ur-rahman Salahuddin M.Akbar Centre for Advanced Mathematics and Physics National University of Sciences and Technology(NUST)IslamabadPakistan

We construct various cases for validity of the generalized second law(GSL)of thermodynamics by assuming the logarithmic correction to the horizon entropy of an evolving *** is shown that the GSL is always respected fo... 详细信息

关键词： correction thermodynamics horizon

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Parametric study and effect of calcination and carbonation conditions on the CO_2 capture performance of lithium orthosilicate sorbent

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Chinese Journal of Chemical Engineering 2018年第3期26卷 631-641页

作者： Nurul Azrin Zubbri Abdul rahman Mohamed Maedeh Mohammadi Low Carbon Economy (LCE) Research Group School of Chemical Engineering Engineering Campus Universiti Sains Malaysia Faculty of Chemical Engineering Babol Noushirvani University of Technology

The world is currently facing the challenges of global warming and climate change. Numerous efforts have been taken to mitigate CO2 emission, among which is the use of solid sorbents for CO2 capture. In this work, Li4SiO4 was synthesised via a sol-gel method using lithium nitrate （LiNO3） and tetraethylorthosilicate （SiC8H20O4） as precursors. A parametric study of Li：Si molar ratio （1-5）, calcination temperature （600-800℃） and calcination time （1-8 h） were conducted during sorbent synthesis. Calcination temperature （700-800℃） and carbonation temperature （500-700℃） during CO2 sorption activity were also varied to confirm the optimum operating temperature. Sorbent with the highest CO2 sorption capacity was finally introduced to several cyclic tests to study the durability of the sorbent through 10 cycles of CO2 sorption-desorption test. The results showed that the calcination temperature of 800℃ and carbonation temperature of 700℃ were the best operating temperatures, with CO2 sorption capacity of 7.95 mmol CO2·（g sorbent）^-1 （93% of the theoretical yield）. Throughout the ten cyclic processes, CO2 sorption capacity of the sorbent had dropped approximately 16.2% from the first to the tenth cycle, which was a reasonable decline. Thus, it was concluded that Li4SiO4 is a potential CO2 solid sorbent for high temperature CO2 capture activity.

关键词： CO2 capture Adsorption Carbon dioxide Lithium orthosilicate Sol-gel Sorption-desorption

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Study of Environmental Radiation on Sand and Soil Samples from Kuakata Sea Beach of Patuakhali

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Journal of Environmental Protection 2012年第9期3卷 1078-1084页

作者： khondaker Mohammed Nazrul Islam Debasish Paul Md. Mahbubur rahman Bhuiyan Amina Akter Budrun Neher Sheikh Mohammad Azharul Islam Department of Physics Comilla University Comilla Bangladesh Department of Physics Jahangirnagar University Savar Bangladesh Health Physics & Radioactive Waste Management Unit (HP & RWMU) Institute of Nuclear Science & Technology (INST) Atomic Energy Research Establishment (AERE) Savar Bangladesh

The activity concentrations of radionuclides in the sand and soil samples collected from Kuakata seabeach of Patuakhali district in Bangladesh have measured using a high resolution high purity germanium (HPGe) detector of relative efficiency 40%. The activity concentrations of 226Ra, 232Th and 40K were found in the sand samples of Kuakata seabeach varied from 2.82 ± 4.89 to 87.96 ± 4.45 ***–1, 21.72 ± 16.27 to 290.93 ± 18.15 ***–1 and 26.24 ± 0.35 to 852.05 ± 142.15 ***–1 respectively. For soil samples the activity concentrations of corresponding radionuclides were found to be 20.98 ± 3.96 to 42.92 ± 4.76 ***–1, 59.25 ± 15.62 to 144.34 ± 18.52 ***–1 and 570.43 ± 100.3 to 1165 ± 166.27 ***–1 respectively. The average absorbed dose rate due to radionuclides in sand was estimated to range from 51.84 to 246.55 nGy.h–1 with an average of 98.33 nGy.h–1. Also the average absorbed dose rate due to radionuclides in soil was estimated to range from 76.63 nGy.h–1 to 142.36 nGy.h–1 with an average of 110.04 nGy.h–1. Radium equivalent activities were calculated for the analyzed samples to assess the radiation hazards arising due to the presence of this radionuclide in the samples. Most of the calculated radium equivalent activities are lower than the limit set in the OECD report (370 ***–1). The measured representative level index values for the investigated samples varied in the range 0.8 to 3.75.

关键词： Radionuclide Activity Concentration HPGe detector Kuakata Seabeach 226Ra 232Th and 40K and 137Cs

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Computational Study on a Squid-Like Underwater Robot with Two Undulating Side Fins

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Journal of Bionic Engineering 2011年第1期8卷 25-32页

作者： Md. Mahbubar rahman Yasuyuki Toda Hiroshi Miki Department of Naval Architecture and Ocean Engineering Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita City Osaka 565-0871 Japan

The undulating fin propulsion system is an instance of the bio-inspired propulsion systems. In the current study, the swimming motion of a squid-like robot with two undulating side fins, mimicking those of a Stingray or a Cuttlefish, was investigated through flow computation around the body. We used the finite analytic method for space discretization and Euler implicit scheme for time discretization along with the PISO algorithm for velocity pressure coupling. A body-fitted moving grid was generated using the Poisson equation at each time step. Based on the computed results, we discussed the features of the flow field and hydrodynamic forces acting on the body and fin. A simple relationship among the fin＇s principal dimensions was established. Numerical computation was done for various aspect ratios, fin angles and frequencies in order to validate the proposed relationship among principal dimensions. Subsequently, the relationship was examined base on the distribution of pressure difference between upper and lower surfaces and the distribution of the thrust force. In efficiency calculations, the undulating fins showed promising results. Finally, for the fin, the open characteristics from computed data showed satisfactory conformity with the experimental results.

关键词： biomimetics squid robot undulating fin propulsion efficiency hydrodynamics CFD

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Networked Control Approach for Distributed Generation Systems

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IEEE/CAA Journal of Automatica Sinica 2018年第4期5卷 836-851页

作者： Magdi S.Mahmoud Mohamed Saif Ur rahman Systems Engineering Department King Fahd University of Petroleum and MineralsP.O.Box 5067Dhahran 31261Saudi Arabia

Microgrid has emerged as an answer to growing demand for distributed generation(DG) in power systems. It contains several DG units including microalternator, photovoltaic system and wind generation. It turns out that sustained operation relies on the stability of these constituent systems. In this paper, a microgrid consisting of microalternator and photovoltaic system is modeled as a networked control system of systems(So S)subjected to packet dropouts and delays. Next, an observerbased controller is designed to stabilize the system in presence of the aforementioned communication constraints and simulation results are provided to support the control design methodology.

关键词： Microalternator microgrid systems networked control observer-based controller photovoltaic systems

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Heavy smoking and liver

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World Journal of Gastroenterology 2006年第38期12卷 6098-6101页

作者： Abdel-rahman El-Zayadi Department of Tropical Medicine Ain Shams University and Director of Cairo Liver Center Cairo Egypt

Smoking causes a variety of adverse effects on organs that have no direct contact with the smoke itself such as the liver. It induces three major adverse effects on the liver: direct or indirect toxic effects, immunological effects and oncogenic effects. Smoking yields chemical substances with cytotoxic potential which increase necroinflammation and fibrosis. In addition, smoking increases the production of pro-inflammatory cytokines (IL-1, IL-6 and TNF-α) that would be involved in liver cell injury. It contributes to the development of secondary polycythemia and in turn to increased red cell mass and turnover which might be a contributing factor to secondary iron overload disease promoting oxidative stress of hepatocytes. Increased red cell mass and turnover are associated with increased purine catabolism which promotes excessive production of uric acid. Smoking affects both cell-mediated and humoral immune responses by blocking lymphocyte proliferation and inducing apoptosis of lymphocytes. Smoking also increases serum and hepatic iron which induce oxidative stress and lipid peroxidation that lead to activation of stellate cells and development of fibrosis. Smoking yields chemicals with oncogenic potential that increase the risk of hepatocellular carcinoma (HCC) in patients with viral hepatitis and are independent of viral infection as well. Tobacco smoking has been associated with supression of p53 (tumour suppressor gene). In addition, smoking causes suppression of T-cell responses and is associated with decreased surveillance for tumour cells. Moreover, it has been reported that heavy smoking affects the sustained virological response to interferon (IFN) therapy in hepatitis C patients which can be improved by repeated phlebotomy. Smoker’s syndrome is a clinico-pathological condition where patients complain of episodes of facial flushing, warmth of the palms and soles of feet, throbbing headache, fullness in the head, dizziness, lethargy, prickling sensation, p

关键词： Iron overload Interferon response Hepatitis C virus Smoking Fibrosis Hepatocellular carcinoma Polycythemia

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