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A Trend Analysis of Temperature and Rainfall to Predict Climate Change for Northwestern Region of Bangladesh

American Journal of Climate Change 2018年第2期7卷 115-134页

作者： md. didarul islam Bhuyan md. Mohymenul islam md. Ebrahim Khalil Bhuiyan Department of Physics Mawlana Bhashani Science and Technology University Santosh Tangail Bangladesh Department of Textile Engineering Bangladesh University of Business and Technology Dhaka Bangladesh

Bangladesh is one in all the foremost climate vulnerable countries of the world. In recent years, climate change studies over the country get plenty of attention by the researchers and policy makers. A substantial quantity of global climate change studies over the country use climate models to estimate future projections and uncertainties. Maximum temperature, precipitation and their potential future changes are evaluated in an ensemble of the 5th Phase Coupled Model Inter-comparison Project (CMIP5) within the Intergovernmental Panel on Climate Change (IPCC) diagnostic exercise for the Fifth Assessment Report (AR5) and the available historical data collected by the Bangladesh Meteorological Department (Bmd. during the period 1981-2008 in the north-western region of Bangladesh and also the comparison between these two values. It has been found that average maximum temperature shows a positive trend of increase at a rate of 0.29°C and 5.3°C per century respectively, for Bmd.data and MPI-ESM-LR (CMIP5) model data. But the rainfall is decreasing at a rate of 8.8 mm and 40.1 mm per century respectively for Bmd.data and MPI-ESM-LR (CMIP5) model data. It is seen that July was the maximum monsoon rainfall month and January was the lowest rainfall month. The peak frequency is slightly smaller than 12 months, which indicates that the major events are occurring before ending a year compared to the previous year. According to MPI-ESM-LR (CMIP5) model data, future normal temperature on north-western region will be increased at a rate of 1.62°C during the period 2040-2100.

关键词： Trend Analysis Mann-Kendall Test Sen’s Slope Estimator Z-Test CMIP5 Model and Periodicity

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Analysis of the Adsorption of Toxic Chromium (VI) by Untreated and Chitosan Treated Banana and Areca Fiber

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Journal of Textile Science and Technology 2020年第2期6卷 81-106页

作者： Hosne Ara Begum A. K. M. Monjurul Haque md. didarul islam M. Mehedi Hasan Suza Ahmed md. Razzak Ruhul Amin Khan Department of Yarn Engineering Bangladesh University of Textiles Dhaka Bangladesh Department of Applied Science & Chemical Engineering University of Dhaka Dhaka Bangladesh Department of Fabric Engineering Bangladesh University of Textiles Dhaka Bangladesh Institute of Radiation and Polymer Technology Bangladesh Atomic Energy Commission Dhaka Bangladesh

This paper work involves bunch experiments to investigate the effect of contact time, pH, and adsorbent dose on the extent of adsorption by bio-composites. Adsorption capacity of Chromium (VI) onto chitosan coated with banana and areca fiber was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and adsorbent dose. The chitosan and fibers (banana and areca) were then cross-linked with glutaraldehyde to remove chromium [Cr (VI)] from water via static adsorption. It was found that optimum chromium absorption capacity of chitosan was assessed at pH of 2.5 to 4.5 and contact time of 30 to 180 minutes for raw banana and areca fiber and for chitosan treated banana & areca fiber. Though optimum adsorption of chromium of chitosan was measured 34.17 ppm (85.42%) from a 100 ml solution containing 40 parts per million (ppm) of Cr (VI) at 120 minutes, pH of 3.0 and 120 milligram (mg) adsorbent dose size, use of composite will be more favorable in the point of environmental concern as well as low cost because chitosan preparation is comparatively costly then banana and areca fiber. On the other hand, untreated banana and areca fiber optimum adsorption of chromium measured 3.65 ppm (9.1%) at 180 min and, pH of 4.5 and 140 mg adsorbent dose size and 3.76 ppm (9.4%) at 180 min, pH of 4.5 and 160 mg adsorbent dose size respectively. In case of chitosan treated banana fiber, it was observed that adsorption was increased from 17.664 to 30.057 (75.14%). On the other hand, for areca fiber with chitosan, it was observed that adsorption was increased from 21.664 to 30.156 (75.39%) ppm. The Langmuir and Freundlich adsorption models were used for the mathematical description of the adsorption of chromium ion onto composites and it was found that the Langmuir adsorption isotherm was more fitted models which mean that a monolayer adsorption surface was created. After analyzing from IBM SPSS 25 software, we got the stand

关键词： Adsorption Heavy Metal Chitosan Banana Fiber Areca Fiber Toxicity

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Fluid Flow and Infrared Image Analyses on Endwall Fitted with Short Rectangular Plate Fin

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Journal of Thermal Science 2006年第2期15卷 145-151页

作者： Kenyu OYAKAWA islam md. didarul Minoru YAGA Dept. of Mechanical Systems Engineering University of the Ryukyus Okinawa Japan. Faculty of Engineering University of the Ryukyus Okinawa Japan.

An experimental investigation is carded out to study fluid flow and heat transfer characteristics on the endwall fitted with arrays （ 7 × 7 ） of short rectangular plate fins of different pattern （co-angular and zigzag） for different pitch ratio. Experiments were conducted in a rectangular duct of 50 mm height for an air flow of Reynolds number ranged from 18750 to 62500 based on the equivalent diameter and air velocity of the duct. Infrared image analysis technique was employed to make clear the characteristics of local heat transfer coefficients on fin base, endwall and overall surface. Flow pattern around the short rectangular plates were visualized by inducing fluorescent dye in a water channel and longitudinal vortices were observed. Increasing the distance between plates in flow direction causes heat transfer enhancement for co-angular pattern, while decreasing the distance causes heat transfer enhancement for zigzag pattern. Zigzag pattern with pitch ratio 2 is found to be more effective in heat transfer enhancement than any other cases investigated.

关键词： infrared image rectangular plate convection heat transfer flow visualization

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Annual pattern of zooplankton communities and their environmental response in a subtropical maritime channel system in the northern Bay of Bengal, Bangladesh

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Acta Oceanologica Sinica 2018年第8期37卷 65-73页

作者： ABDULLAH Al Mamun ALAM md.didarul AKHTAR Aysha XU Henglong islam md.Shafiqul MUSTAFA KAMAL Abu Hena UDDIN M Muslem ALAM md.Wahidul Laboratory of Microbial Ecology Ocean University of China Faculty of Marine Sciences and Fisheries University of Chittagong Department of Animal Science and Fishery Faculty of Agriculture and Food Sciences Universiti Putra Malaysia Campus Bintulu

Zooplankton plays an important role in aquatic food webs by fluxing of energy from primary producer to subsequent trophic levels in the food chain. The annual pattern of zooplankton communities and potential environmental drivers were studied in the Kohelia channel, Bangladesh from summer 2014 to spring *** were collected using net at a depth of 1 m. A total of 32 species belonged to 18 orders, 27 families and 15 taxonomic groups were identified. Of these species, 22 distributed in all four seasons of which 8 were dominant and highly contributing to the total communities. Species number peaked in summer next to winter and fall in spring while maximum abundance was in summer and minimum in spring. Multivariate analyses showed that there was a clear annual pattern in the zooplankton communities. Species diversity and evenness peaked in spring but fall in autumn while the high value of species richness was found in winter. Biological-environmental best matching（BIO-ENV） analyses conformed that community pattern of zooplankton was mainly driven by transparency salinity, and temperature individually or combined with water nutrients. These results demonstrate that annual pattern of the zooplankton community shaped by channel environmental factors in subtropical channel ecosystems, thus might be used for community-based subtropical coastal water bioassessment.

关键词： zooplankton trophic levels subtropical channel community structure multivariate approach

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A Study on Heat Transfer Enhancement through Various Nanofluids in a Square Cavity with Localized Heating

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Energy Engineering 2021年第6期118卷 1659-1679页

作者： Sheikh Hassan didarul Ahasan Redwan md.Mamun Molla Sharaban Thohura M.Abu Taher Sadia Siddiqa Department of Mathematics and Physics North South UniversityDhakaBangladesh Center for Applied and Scientific Computing(CASC) North South UniversityDhakaBangladesh Department of Mathematics Jagannath UniversityDhakaBangladesh Department of Mathematics Dhaka University of Engineering and TechnologyGazipurBangladesh Department of Mathematics COMSAT University IslamabadAttock CampusAttockPakistan

A two-dimensional(2D)laminar flow of nanofluids confined within a square cavity having localized heat source at the bottom wall has been *** governing Navier–Stokes and energy equations have been non dimensionalized using the appropriate non dimensional variables and then numerically solved using finite volume *** flow was controlled by a range of parameters such as Rayleigh number,length of heat source and nanoparticle volume *** numerical results are represented in terms of isotherms,streamlines,velocity and temperature distribution as well as the local and average rate of heat transfer.A comparative study has been conducted for two different base fluids,ethylene glycol and water as well as for two different solids Cu and Al_(2)O_(3).It is found that the ethylene glycol-based nanofluid is superior to the water-based nanofluid for heat transfer enhancement.

关键词： Nanofluids finite volume method heat transfer enhancement localized heating

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The Activity Concentrations, Radiation Contamination, and Hazards from Wastes and Soil Samples in Nasirabad Industrial Area, Chattogram, Bangladesh

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Journal of Environmental Protection 2020年第10期11卷 767-778页

作者： Mohammed didarul Alam Mojumd.r Mahiuddin Ahmed Masud Kamal Mohammad Belal Hossen md. Abdur Rashid Department of Physics Chittagong University of Engineering and Technology Chattogram Bangladesh Atomic Energy Centre Chattogram Bangladesh Atomic Energy Commission Chattogram Bangladesh

Soils and other solid wastes from industrial areas of Nasirabad, Chattogram are usually dumped or used for land development. Information about the radioactivity level presented on these soil and wastes enables one to assess any possible radiological hazard to humankind by the use of such materials. A total of 37 (31 soils and 6 solid waste) samples near from different types of industries along four kilometre range were collected. The presence and activity concentrations of naturally occurred radioactive materials (NORM) and anthropogenic radionuclides in the samples were estimated using HPGe detector of 40% relative efficiency. The activity concentration of 226Ra, 232Th and 40K were found to be ranging from 8 ± 2 to 131 ± 18.33 with an average of 21 Bq·kg-1, 10 ± 2.69 to 133 ± 15.96 with an average of 40 Bq·kg-1 and 81 ± 22.68 to 930 ± 260.40 with an average of 449 Bq·kg-1 respectively. Besides this, some hazard indices like, the radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), and the activity concentration index (Iy) were calculated to assess the radiation hazard in this region. The averages of calculated hazard indices were within the normal limits, except the activity concentration index, which shows elevated values. The outcomes of this study could serve as important baseline radiological data for future epidemiological studies and environmental monitoring initiatives in the study area.

关键词： Industrial Contamination Gamma Spectrometry Activity Concentration Hazard Index

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