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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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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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Seasonal influence of freshwater discharge on spatio-temporal variations in primary productivity, sea surface temperature, and euphotic zone depth in the northern Bay of Bengal

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Acta Oceanologica Sinica 2024年第6期43卷 1-14页

作者： Hafez Ahmad Felix Jose md.Simul bhuyan md.Nazrul islam Padmanava Dash Geosystems Research Institute/Department of Geosciences Mississippi State UniversityStarkville 39759USA Department of Oceanography University of ChittagongChittagong 4331Bangladesh Department of Marine&Earth Sciences Florida Gulf Coast UniversityFort Myers 33965USA Bangladesh Oceanographic Research Institute Cox’s Bazar 4730Bangladesh Faculty of Marine Sciences&Fisheries Institute of Marine SciencesUniversity of ChittagongChittagong 4331Bangladesh Department of Geography and Environment Jahangirnagar UniversityDhaka 1342Bangladesh Department of Geosciences Mississippi State UniversityStarkville 39759USA

Ocean productivity is the foundation of marine food web,which continuously removes atmospheric carbon dioxide and supports life at sea and on ***-temporal variability of net primary productivity(NPP),sea surface temperature(SST),sea surface salinity(SSS),mixed layer depth(MLD),and euphotic zone depth(EZD) in the northern B ay of Bengal(BoB) during three monsoon seasons were examined in this study based on remote sensing data for the period 2005 to *** compare the NPP distribution between the coastal zones and open BoB,the study area was divided into five zones(Z1-Z5).Results suggest that most productive zones Z2 and Zl are located at the head bay area and are directly influenced by freshwater discharge together with riverine sediment and nutrient *** Z1-Z5,the NPP ranges from 5 315.38 mg/(m^(2)·d) to 346.7 mg/(m^(2)·d)(carbon,since then the same).The highest monthly average NPP of 5 315.38 mg/(m^(2)·d) in February and 5 039.36 mg/(m^(2)·d) in June were observed from Z2,while the lowest monthly average of 346.72 mg/(m^(2)·d) was observed in March from Z4,which is an oceanic *** values vary from 6-154 m for the study area,and it has an inverse correlation with NPP *** is deeper during the summer season and shallower during the wintertime,with a corresponding increase in *** the year,monthly SST shows slight fluctuation for the entire study area,and statistical analysis shows a significant correlation among NPP,and EZD,overall positive between NPP and MLD,whereas no significant correlation among SSS,and SST for the northern ***-term trends in SST and productivity were significantly po sitive in head bay zones but negatively productive in the open *** findings in this study on the distribution of NPP,SST,SSS,MLD,and EZD and their seasonal variability in five different zones of BoB can be used to further improve the management of marine resources and overall environmental condition in response to clim

关键词： chlorophyll a sea surface temperature euphotic zone depth primary productivity Ganges-Brahmaputra ocean color Bay of Bengal monsoon

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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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Increasing yield and agronomic efficiency of boro rice(Oryza sativa)by fertigation with bed planting compared with conventional planting

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International Journal of Agricultural and Biological Engineering 2014年第5期7卷 34-47页

作者： md.Halim Mahmud bhuyan Most.Razina Ferdousi md.Toufiq Iqbal Department of Farm Machinery Chuadanga Technical School and CollegeChuadanga 7200Bangladesh islamia Academy High School&Agriculture College BaghaRajshahi 6280Bangladesh Department of Agronomy and Agricultural Extension University of RajshahiRajshahi 6205Bangladesh

The fertigation technique with raised bed planting for transplanted boro(winter,irrigated)rice production is a research focus nowadays.A field experiment compared two cultivation methods:the fertigation technique within raised bed planting on boro rice,and fertilizer broadcasting in the conventional planting *** to conventional fertilizer broadcasting,results showed that the new fertigation technique in raised bed planting increased grain yield of transplanted boro rice by up to 17.04%.It yielded a greater number of panicles per square meter,a greater number of grains per panicle,higher 1000-grains weight,and better plant growth *** percentage and weed infestation were *** six percent of irrigation water and time for application could be *** use efficiency for grain and biomass production was *** agronomic efficiency of nitrogen(N)fertilizer was significantly *** study concluded that fertigation in raised bed planting for transplanted boro rice is a new approach with higher yield and higher fertilizer and water use efficiency than the existing agronomic practice in Bangladesh.

关键词： boro rice fertigation with bed planting de-nitrification water use efficiency harvest index irrigated water management

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Effectiveness of hybrid ensemble machine learning models for landslide susceptibility analysis:Evidence from Shimla district of North-west Indian Himalayan region

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Journal of Mountain Science 2024年第7期21卷 2368-2393页

作者： SHARMA Aastha SAJJAD Haroon RAHAMAN md.Hibjur SAHA Tamal Kanti bhuyan Nirsobha Department of Geography Faculty of SciencesJamia Millia IslamiaNew Delhi-110025India

The Indian Himalayan region is frequently experiencing climate change-induced ***,landslide susceptibility assessment assumes greater significance for lessening the impact of a landslide *** paper makes an attempt to assess landslide susceptibility in Shimla district of the northwest Indian Himalayan *** examined the effectiveness of random forest(RF),multilayer perceptron(MLP),sequential minimal optimization regression(SMOreg)and bagging ensemble(B-RF,BSMOreg,B-MLP)models.A landslide inventory map comprising 1052 locations of past landslide occurrences was classified into training(70%)and testing(30%)*** site-specific influencing factors were selected by employing a multicollinearity *** relationship between past landslide occurrences and influencing factors was established using the frequency ratio *** effectiveness of machine learning models was verified through performance *** landslide susceptibility maps were validated by the area under the receiver operating characteristic curves(ROC-AUC),accuracy,precision,recall and *** key performance metrics and map validation demonstrated that the BRF model(correlation coefficient:0.988,mean absolute error:0.010,root mean square error:0.058,relative absolute error:2.964,ROC-AUC:0.947,accuracy:0.778,precision:0.819,recall:0.917 and F-1 score:0.865)outperformed the single classifiers and other bagging ensemble models for landslide *** results show that the largest area was found under the very high susceptibility zone(33.87%),followed by the low(27.30%),high(20.68%)and moderate(18.16%)susceptibility *** factors,namely average annual rainfall,slope,lithology,soil texture and earthquake magnitude have been identified as the influencing factors for very high landslide *** texture,lineament density and elevation have been attributed to high and moderate ***,the study calls for devising suitable landslide mitig

关键词： Landslide susceptibility Site-specific factors Machine learning models Hybrid ensemble learning Geospatial techniques Himalayan region

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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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Microplastic pollution:An emerging contaminant in aquaculture

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Aquaculture and Fisheries 2023年第6期8卷 603-616页

作者： Stanley Iheanacho Miracle Ogbu md.Simul bhuyan Johnny Ogunji Department of Fisheries and Aquaculture Alex Ekwueme Federal UniversityNdufu Alike Ebonyi StateAbakalikiP.M.B.1010Nigeri Department of Biology Alex Ekwueme Federal UniversityNdufu Alike Ebonyi StateAbakalikiP.M.B.1010Nigeria Bangladesh Oceanographic Research Institute Cox’s Bazar4730Bangladesh

Aquaculture largely contributes to aquatic products and consequential dietary protein for many ***,just like every other food sector,is faced with enormous challenges such as unfavorable climatic events,environmental stressors and ***(MP)are emerging contaminants in aquaculture following their perturbing occurrence in cultured fish,fishmeal and *** MPs pathways into aquaculture facilities include wastewater,pipe-borne water,dilapidated aquaculture facilities,fish gears,and aquafeed stuff(fishmeal).Techniques for the digestion,identification and characterization of MPs are critical to understanding their pathways,bioavailability and bioaccumulation patterns in aquaculture *** impacts of MPs on cultured fish species are identified as impaired growth,oxidative stress,neurotoxicity,reproductive toxicity,immunotoxicity,embryotoxicity,and *** of MPs in tissues and biological systems have been evidenced in several cultured *** efforts cum strategies such as upgrade of wastewater treatment facilities,screening of inlet pond water,screening of aquafeed stuff,regular maintenance and repair of culture facilities,could be effective to eradicate MP contamination in ***,regulatory policy on the use of plastics is key to mitigating the impact of MPs and ensure cleaner and sustainable aquaculture.

关键词： Microplastics Aquaculture Sources Impact Mitigation

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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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Augmentation of Heat Transfer in Pipe Flow Using Plain Twisted Tape Inserts for Different Twist Ratios

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Energy and Power Engineering 2019年第9期11卷 342-354页

作者： Maimonul Karim Chowdhury md. Moniruzzaman bhuyan Ujjwal Kumar Deb Department of Science & Humanities Military Institute of Science and Technology Mirpur Cantonment Dhaka Bangladesh Department of Mathematics Chittagong University of Engineering & Technology Chittagong Bangladesh

The heat transfer augmentation of plain twisted tape inserts for different twist ratios has been studied in this study. The data are conducted using the plain twisted tape insert with five different twist ratios respectively. The range of Reynolds number is considered under a uniform heat flux condition. In the case of simulation, the tapes are made from a stainless steel strip with a thickness of 2 mm. A tubular pipe with 850mm U-loop length and twist length of 800 mm each is considered in our study for simulation. Water is used as working fluids inside the tube for our simulation. The simulation results demonstrate that the important heat transfer parameters including Nusselt number (Nu), friction factor (f) and thermal performance index (η) are gradually increased with the increment of the twist ratio and reached at the saturated level while twist ratio is 3.5,?afterward the thermal properties are decreased.

关键词： Heat Transfer Twist Ratio Reynolds Number Turbulent Flow Simulation

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