Aerodynamic response of articulated towers: state-of-the-art

M. Moonis Zaheer,Nazrul Islam 한국풍공학회 2008 Wind and Structures, An International Journal (WAS Vol.11 No.2

Wind and wave loadings have a predominant role in the design of offshore structures in general, and articulated tower in particular for a successful service and survival during normal and extreme environmental conditions. Such towers are very sensitive to the dynamic effects of wind and wind generated waves. The exposed superstructure is subjected to aerodynamic loads while the submerged substructure is subjected to hydrodynamic loads. Articulated towers are designed such that their fundamental frequency is well below the wave frequency to avoid dynamic amplification. Dynamic interaction of these towers with environmental loads (wind, waves and currents) acts to impart a lesser overall shear and overturning moment due to compliance to such forces. This compliancy introduces geometric nonlinearity due to large displacements, which becomes an important consideration in the analysis of articulated towers. Prediction of the nonlinear behaviour of these towers in the harsh ocean environment is difficult. However, simplified realistic mathematical models are employed to gain an important insight into the problem and to explore the dynamic behaviour. In this paper, various modeling approaches and solution methods for articulated towers adopted by past researchers are reviewed. Besides, reliability of articulation system, the paper also discussed the design, installation and performance of articulated towers around the world oceans.

One-pot synthesis of high magnetization air-stable FeCo nanoparticles by modified polyol method

Abbas, M.,Nazrul Islam, Md.,Parvatheeswara Rao, B.,Ogawa, T.,Takahashi, M.,Kim, C. North-Holland 2013 Materials letters Vol.91 No.-

High magnetization FeCo nanoparticles with different Fe/Co ratios have been successfully synthesized by surfactant free simple modified polyol method. Polyethylene glycol (PEG) was used as solvent and reducing agent simultaneously in this synthesis process. All the synthesized samples of FeCo nanoparticles were annealed at 600<SUP>o</SUP>C before characterizations. X-ray diffraction (XRD) data on the samples confirm formation of a body-centered-cubic single phase structure in all the compositions. Transmission Electron Microscopy (TEM) data suggest that the annealed FeCo nanoparticles are of 50-90nm in size. The use of PEG and the annealing procedure employed ensure that the obtained nanoparticles are stable in air. This observation is well supported by both the analysis of Energy Dispersive Spectrometry (EDS) and the images of TEM which establish the formation of a thin passive oxide layer over the FeCo nanoparticles thereby resulting in the stability of the nanoparticles. The physical Property Measurement System (PPMS) reveals that the Fe<SUB>60</SUB>Co<SUB>40</SUB> composition among all the samples exhibit highest saturation magnetization of 230.14emu/g at 5K.

Aerodynamic response of articulated towers: state-of-the-art

Zaheer, M. Moonis,Islam, Nazrul Techno-Press 2008 Wind and Structures, An International Journal (WAS Vol.11 No.2

Wind and wave loadings have a predominant role in the design of offshore structures in general, and articulated tower in particular for a successful service and survival during normal and extreme environmental conditions. Such towers are very sensitive to the dynamic effects of wind and wind generated waves. The exposed superstructure is subjected to aerodynamic loads while the submerged substructure is subjected to hydrodynamic loads. Articulated towers are designed such that their fundamental frequency is well below the wave frequency to avoid dynamic amplification. Dynamic interaction of these towers with environmental loads (wind, waves and currents) acts to impart a lesser overall shear and overturning moment due to compliance to such forces. This compliancy introduces geometric nonlinearity due to large displacements, which becomes an important consideration in the analysis of articulated towers. Prediction of the nonlinear behaviour of these towers in the harsh ocean environment is difficult. However, simplified realistic mathematical models are employed to gain an important insight into the problem and to explore the dynamic behaviour. In this paper, various modeling approaches and solution methods for articulated towers adopted by past researchers are reviewed. Besides, reliability of articulation system, the paper also discussed the design, installation and performance of articulated towers around the world oceans.

Modeling on the spatial vulnerability of lightning disaster in Bangladesh using GIS and IDW techniques

Biswas Rathindra Nath,Islam Md. Nazrul,Mia Md. Juel,Islam M. Nazrul 대한공간정보학회 2020 Spatial Information Research Vol.28 No.5

This paper tries to explore the spatial patterns of lightning disaster death susceptibility in Bangladesh. It is prior need to identify the factors of death due to lightning hazard, seasonal variability, and spatial risks to develop management strategies of this country. To reach the study goal, lightning fatalities data were collected from the Ministry of Disaster Management and Relief, Bangladesh. The geostatistical IDW model of GIS technology was applied to assess the spatial vulnerability of lightning disaster. The geospatial prediction maps produced from the study determines the spatial heterogeneity of lightning risk. Generated statistics demonstrates that the Surma Basin, northwest Brinda tract, and northern Tertiary hilly region of Bangladesh are more susceptible to lightning disaster during the time span 2015–2018. Analysis results also discloses numerous factors such as climatic variability, geomorphological diverseness and anthropogenic phenomena influencing lightning catastrophes. Moreover, this study suggests that government and non-government disaster management organizations can play vital role to take initiative in risk assess, policy creation review, awareness building and campaign, community-based early warning system, emergency management system and appropriate technology piloting as well as implementation. The rationale of this study will contribute to assess spatial lightning strikes, mitigate locational vulnerability and promote sustainable development plans for reducing lightning disaster risk. In the future, GIS-based communication model like this can applied to raise awareness and educating and engaging the public through public–private partnership of the lightning hot spot regions.

Facile one-pot chemical approach for synthesis of monodisperse chain-like superparamagnetic maghemite (g-Fe2O3) nanoparticles

Mohamed Abbas,김철기,Md. Nazrul Islam,B. Parvatheeswara Rao,M.O. Abdel-Hamed 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.31 No.-

In this study, we demonstrated a novel and facile chemical approach for synthesis of monodispersemaghemite (g-Fe2O3) nanoparticles. Compared to the reported works for synthesis of maghemitenanoparticles which require the use of much amount of surfactant and complicated procedures, wecould develop here an approach in which we did not use any surfactant or deoxygenated condition andfurther the synthesis process was also completed in a single reaction. X-ray diffraction analysis of thesample confirms single phase fully crystalline spinel structure. Transmission electron microscopyimages reveal that the shape of the synthesized maghemite nanoparticles is a mix of spherical and cubewith chain-like patterns and the average particles size is of 25 nm. The obtained maghemite (g-Fe2O3)nanoparticles showed high magnetic moment of 65 emu/g with superparamagnetic properties. Owing tothe high moment, mono disperse superparamagnetic nature of the sample, the synthesized maghemitenanoparticles are useful for biomedical applications.

Customer's Attitude toward Mobile Banking Usage: A Case Study in Bangladesh

AL AMIN, Md.,SULTANA, Nahida,SAHA, Trina,ISLAM, S.M. Nazrul,KASHEM, Md. Abul 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2

Mobile banking brings about a progressive change in the field of banking sectors in Bangladesh. To create a sustainable banking environment, technological implementation is important. As a part of this, many organizations as well as modern banks propelled mobile banking systems in Bangladesh. The customers' attitudes towards mobile banking are fascinating in Bangladesh. So, it is important for mobile banking authority to know what factors influence customers' positive attitude towards mobile banking usage and whether they are facing problems in using mobile banking. To evaluate the customers' attitude toward mobile banking usage in Bangladesh is the main objective of this study. People who use mobile banking have been considered for the study. Respondents were reached out based on their online activities. Around 400 questionnaires have been sent to respondents, but only 200 were returned with responses. A quantitative research design was used for this study. As regards statistical analysis tools, descriptive statistics, factor analysis, and regression analysis have been adopted for analyzing the research study. The results revealed that usage benefits, shopping benefits, and psychological factors influence customers' positive attitude toward mobile banking usage in Bangladesh. Besides, some problems with mobile banking usage are identified by the respondents.

The Impact of COVID-19 on the Volatility of Bangladeshi Stock Market: Evidence from GJR-GARCH Model

Uttam GOLDER,Nishat RUMALY,A. H. M. SHAHRIAR,Mohammad Jahangir ALAM,A. Amin BISWAS,Mohammad Nazrul ISLAM 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.4

The enormous sway of COVID-19 on the international financial market has been felt across the globe. The financial markets of Bangladesh have also been similarly affected by the global epidemic and experienced a significant increase in volatility. To scrutinise the connection between COVID-19 and the Dhaka Stock Exchange (DSE) indices’ return and instability, this study uses data of the DSE from February 2014 to September 2021. A comparative examination of the return and instability of the stock indices of the DSE has also been done considering the outbreak of the current COVID-19 situation. After using the GJR-GARCH (1,1) model, this review uncovers that the outbreak of COVID-19 has a statistically positive noteworthy association with the DSE stock indices’ instability, which increases the market’s volatility. Traders’ fear and the rising frequency of COVID-19 reported patients could cause this. Besides, according to this study, COVID-19 shows a substantial positive linkage with stock market returns that increases the market’s return. An appealing valuation, lower interest rates in the banking channel, economic rebound following the closure to prevent coronavirus transmission, improved remittance inflows, and a return of export revenues could all have contributed to this outcome. In addition, the findings also reveal that all market indices are in a mean-reverting phase.

Dermatopathology in respect to bovine cutaneous streptothricosis with clinical observations at Dinajpur of Bangladesh

( Mst. Sogra Banu Juli ),( Md. Fazlul Hoque ),( Begum Fatema Zohara ),( S. M. Harun Ur Rashid ),( Md. Nazrul Islam ),( Md. Siddiqur Rahman ),( Hee Jong Song ) 한국동물위생학회 2011 한국동물위생학회지 (KOJVS) Vol.34 No.1

Dermatopathologic findings on cutaneous streptothricosis (bovine dermatophilosis) were conducted in Dinajpur of Bangladesh for one year. The animals were examined clinically at hospital during the physical visit of the affected animals and clinical manifestations and patients` history were recorded. The gross lesions were systematically examined, noted and categorized. An impression smear was made by the skin scraps, stained with Gram`s stain and examined microscopically for the presence of causative bacteria. The suitable sizes of skins of 3 animals typically affected with dermatophilosis were collected surgically from the animals, and prepared for the histopathological study. The cardinal clinical features and gross lesions were characterized as paint-brush cutaneous surface with matted hairs, scab and crust formation, roughened coat; histopathologically as hyperkeratosis, parakeratosis, typical palisading encrustations, extensive proliferation of coccoid shaped, bluish coloured bacteria (zoospores) in the cells of the outer rootsheath of the hair follicles, separation of keratinized layer from the epidermal epithelium, epidermal hyperplasia, densely cellular dermis with moderate destruction of glandular structures. Coccoid shaped gram positive organisms which form multidimensional arrangement were also observed by impression smear. The clinical signs, gross lesions, morphology of the organisms, staining properties, and histopathological features of the affected skin were diagnostic criteria for the bovine cutaneous streptothricosis.

Dermatopathology in respect to bovine cutaneous streptothricosis with clinical observations at Dinajpur of Bangladesh

Juli, Sogra Banu Mst.,Hoque, Md. Fazlul,Zohara, Begum Fatema,Harun-Ur-Rashid, S.M.,Islam, Md. Nazrul,Rahman, Md. Siddiqur,Song, Hee-Jong The Korean Society of Veterinary Service 2011 韓國家畜衛生學會誌 Vol.34 No.1

Dermatopathologic findings on cutaneous streptothricosis (bovine dermatophilosis) were conducted in Dinajpur of Bangladesh for one year. The animals were examined clinically at hospital during the physical visit of the affected animals and clinical manifestations and patients' history were recorded. The gross lesions were systematically examined, noted and categorized. An impression smear was made by the skin scraps, stained with Gram's stain and examined microscopically for the presence of causative bacteria. The suitable sizes of skins of 3 animals typically affected with dermatophilosis were collected surgically from the animals, and prepared for the histopathological study. The cardinal clinical features and gross lesions were characterized as paint-brush cutaneous surface with matted hairs, scab and crust formation, roughened coat; istopathologically as hyperkeratosis, parakeratosis, typical "palisading encrustations", extensive proliferation of coccoid shaped, bluish coloured bacteria (zoospores) in the cells of the outer rootsheath of the hair follicles, separation of keratinized layer from the epidermal epithelium, epidermal hyperplasia, densely cellular dermis with moderate destruction of glandular structures. Coccoid shaped gram positive organisms which form multidimensional arrangement were also observed by impression smear. The clinical signs, gross lesions, morphology of the organisms, staining properties, and histopathological features of the affected skin were diagnostic criteria for the bovine cutaneous streptothricosis.