Jahangirnagar University Journal of Science

The Effect of Bronchial Compliance along Parallel Channel under Constant Flow

M. Sultana — 2024-10-24

In this study, a numerical simulation is carried out to investigate the nature of flow convection along lower and narrower airways of the parallel channel under constant flow rate through the human lung. This paper aim at to examine the effect of compliance with a real scale model channel (18^th generation) for constant flow. We have graphically illustrated how the variation of compliance affects every flow convection. We also found that the lung model of parallel networks exhibits a larger effect of capacitance when the capacitive time constant is decreased. This implies that a little change in the capacitance C value causes more flow to be diverted into the capacitive tube, which has an impact on our lung model.

Exploring the Utilities of Unmanned Aerial Vehicle (UAV) Imageries for Assessing Planned Housing in a GIS format: A case study of Savar Upazilain Dhaka, Bangladesh

Nessar Uddin Ahmed — 2024-10-24

People's need for a safe and comfortable place to reside is among the most fundamental. But governments worldwide, notably emerging nations like Bangladesh, are finding it increasingly challenging to build housing to meet their needs in light of their growing populations. Therefore, accurate mapping of the housing project area is required to achieve the goals of having planned housing and a sustainable environment. Using an unmanned aerial vehicle (UAV), the purpose of this investigation is to compile a plot-level GIS database from Mauza at the study site of Arunapalli, Savar upazila of Dhaka district, as well as investigate the advantages and drawbacks of employing UAVs to evaluate housing societies. Orthophoto and DTM were the results of the study. This DTM revealed that the RL of the project area ranged from a minimum of 4.93 meters to a high of 11.85 meters. The majority of the land is taken up by vegetation, around 35.76 percent of the total area. According to the findings of the structural analysis, the research area encompasses a total of 207 different structures. Most of the buildings are homes and other residential land uses.

Identifying factors of spatial heterogeneity in COVID-19 incidence for Dhaka Division, Bangladesh

Azizur Rahman — 2024-10-24

The modern world is dealing with a novel infectious disease known as COVID-19, which is rapidly spreading from one person to another or from the environment, causing illness in our communities. The application of geospatial and statistical methods allows researchers to gain a better grasp of the nature of this disease's spatial and temporal dissemination. However, there is a paucity of research on employing the Bayesian framework of spatial modelling for COVID-19 and identifying sources of regional heterogeneity in reported coronavirus (COVID-19) disease. Sociodemographic factors, environmental factors, socio-economic factors, and contact patterns are among the postulated mechanisms that generate regional variation in reported coronavirus (COVID-19) infections. Through the Bayesian framework of the spatial conditional model, we evaluate the impact of socio-demographic factors on observed variance in COVID-19 standardized morbidity rates (SMRs) across seventeen districts of Dhaka divisions. The conditional approach uses random effects in a generalized linear mixed model (GLMM) to account for geographic similarity between observations. We created two types of intrinsic conditional autoregressive (ICAR) models and discovered that the first type performed better in explaining variation in COVID-19 SMR rates throughout the Dhaka division in terms of lowest deviation information requirement (DIC). The results of this model revealed that COVID-19 SRMs were higher in Dhaka, Faridpur, and Rajbari districts, and that only transmission mechanisms-population density was a relevant factor in explaining the change in COVID-19 standardized morbidity rates across the study period. The outcomes of this study will aid in gaining a better understanding of the COVID-19 situation and will serve as a guideline for developing an effective action plan to control and prevent disease spread.

Application of Modified Logistic Model's for an Analysing COVID-19 Transmission in Bangladesh

Md. Asraful Islam — 2024-10-24

In Bangladesh, the logistic model is used to examine possible cases of COVID-19. The prototype is ready to spearhead the fight in Bangladesh against the COVID-19 strain. Direct computation with plausible COVID-19 data for Bangladesh from January 1st, 2022, to the end of the month provides the parameters for the model. In addition to a portrayal of the stability of equilibrium and propositions, this includes both a qualitative assessment of the modified logistic model as well as an analysis of the bifurcation of the modified logistic model. As it turns out, there is a wide chasm between the two. In addition to this, it was found that logistic curves were an appropriate way to describe the COVID-19 outbreak that was occurring in Bangladesh. The suggested model predicts Covid-19 duration and peak times in Bangladesh, which is compared to data. In conclusion, a numerical investigation of the logistic model for Corona virus cases in Bangladesh has been estimated, and its graphical representations have been provided. This model has been used to estimate the number of cases in Bangladesh. It has come to our attention that the cases that were anticipated and the ones that were investigated are extremely similar to one another in a number of important respects.

Mineralogical Influence on the Geotechnical Properties of Shallow Landslide Hazard Site Soils of Rangamati Sadar Area, Bangladesh

Mahmuda Khatun — 2024-10-24

This study has evaluated the mineralogical influence on geoengineering properties of some soil samples of the landslide site in the Rangamati Sadar area, Bangladesh. This research has assessed field data interpretation, i.e. borehole lithology, SPT data analysis, the mineralogical composition, and basic engineering properties such as grain size analysis, moisture content, specific gravity, Atterberg limit i.e., liquid limit, plastic limit, plasticity index, engineering soil classification of Rangamati Sadar, Bangladesh. The studied soil is broadly divided into cohesive and non-cohesive soils and the SPT values increase with increasing depth. The field SPT values suggest that the ground condition of the studied cohesive soil is mainly stiff to hard silty clay (CL-ML) and non-cohesive soils are medium-dense to densely compacted sandy (SM) soil. The uppermost part of cohesive soil up to 3m is mainly composed of silty clay with low SPT values which is highly vulnerable to landslides. The non-cohesive soil sand up to 7.5 m is also highly vulnerable to landslides. The mineralogical information on soil clay and non-clay minerals has been identified by using XRD (X-ray Diffractometer). The non-clay minerals include quartz, orthoclase, plagioclase, and Mica and the clay minerals are mainly illite, chlorite, and kaolinite occur in very small amounts. The natural moisture content values of the samples range from 15.65% to 32.19% and the average is 25.67%. The specific gravity value ranges from 2.20 to 2.93, the average is 2.48, and the values decrease with increasing depth. The obtained values are closer to the values recommended for Illite –Chlorite. For geotechnical investigations, three types of soils (sand, silt, and clay) have been categorized based on grain size distribution. The soil samples are mainly composed of sand with silt and a small amount of clay and might be defined as silty sand. The values of Cu and Cg suggest that the studied soil is well-graded. The liquid limit values range from 28.01% to 48.06%. The plastic limit is in the range of 14.72% to 23.69%. The plasticity index values lie between 7 % and 21.48%. According to the plasticity chart, the Clay soils of Rangamati can be characterized as low to medium plasticity inorganic clay and classified as CL to CM from their position in the plasticity chart which has low to medium swell potential.

Forecasting Monthly RMG Exports Demand in Bangladesh: with or without Change-Point Approach

Sonjit Mondol — 2024-10-24

Time series models assume stationarity, but in reality, the mean and variance of time series often change over time. Though different techniques can stabilize variance, none can stabilize the mean. Hence, detecting change points in the mean is vital to segment the data and maintain stationarity in each segment for accurate modeling and predictions. This study explores change point techniques for identifying changes in the mean of time series data. Using the cumulative summation (CUSUM) test and Binary Segmentation algorithm, this study finds two significant change points in the mean of the monthly average export in million USD of specialized textiles in Bangladesh from July 2011 to July 2021. For forecasting, an ARMA(0,0) model with a non-zero mean is fitted for the data with the change points, while an ARIMA(2,0,0)(1,0,0)[12] model with a non-zero mean is estimated for the entire dataset without the change points. The findings of this research demonstrate that the accuracy of forecasting with the change points model is higher compared to forecasting without change points. Therefore, this study suggests that incorporating change point techniques in time series analysis can improve the forecasting process by considering the potential existence of a change point in the data.

Identifying the Learning Style of the University Students in Bangladesh: Evidence from a Cross-sectional Study

Nusrat Jahan Borna — 2024-10-24

There has been much discussion about learning styles throughout the years, and many scholars have categorized them into different styles. The aim of this study is to identify undergraduate students' preferred learning styles and the associations between gender and various other factors (faculty, academic year, age, result satisfaction, study time, accommodation, general health status and preferred learning and examination pattern). At Jahangirnagar University in Dhaka, Bangladesh, an observational study was conducted among the undergraduate students. The primary data were collected from 572 undergraduate students of Jahangirnagar University. This is the first study where Learning style scale (LSS) was used and the reliability was checked by Cronbach Alpha coefficient (α=0.822). The dimension of LSS questionnaire was reduced using factor analysis. Data were analyzed using the SPSS ver.23 software and chi-square test. In this analysis, among the study variables only examination pattern, result (CGPA), health status and accommodation at 10% significance level. 76% of the pupils prefer offline examination pattern while 24% prefer online. According to the research's findings, students favor offline study methods over online ones.