bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Sensitivity of Microphysical Parameterization Schemes on the Prediction of Tropical Cyclone Mora Over the Bay of Bengal using WRF-ARW Model
Authors: Islam Md Jafrul , Imran Ashik , Syed Ishtiaque M , Hassan SM Quamrul , Ali Md Idris 
Published: July 2021

The sensitivity of Microphysics Parameterization (MP) schemes has been analyzed in the prediction of intensity and track of tropical cyclone (TC) Mora (28th May-31st May, 2017), over the Bay of Bengal (BoB) using WRF model. The study of MP schemes in numerical simulation is important because it includes microphysical process and cloud dynamics that controls the latent heat release in clouds. In this study seven MP schemes (Kessler, Lin, WSM3, Eta, WSM6, MYDM7, and WDM5) are used to study the variation in Mean Sea Level Pressure (MSLP), Maximum Wind Speed (MWS), rainfall distributions, and Tracks. The root mean square error (RMSE) of MSLP, MWS and 72-h simulated tracks are found minimum for WSM3 scheme while the RMSE of rainfall, 48 and 24-h simulated tracks are found minimum for WDM5 scheme. In conclusion, WSM3 and WDM5 schemes may give better results in the prediction of slowly intensifying TC like Mora.
Dhaka Univ. J. Sci. 67(1): 33-40, 2019 (January)
Over-Differencing and Forecasting with Non-Stationary Time Series Data
Authors: Hossain Zakir , Rahman Atikur , Hossain Moyazzem , Karami Jamil Hasan 
Published: July 2021

In time series analysis, over-differencing is a common phenomenon to make the data to be stationary. However, it is not always a good idea to take over-differencing in order to ensure the stationarity of time series data. In this paper, the effect of over-differencing has been investigated via a simulation study to observe how far or how close the fitted model from the true one. Simulation results show that the fitted model is found to be different and very far from the true model because of over-differencing in most of the scenarios considered in this study. In practice, it may be worthy to consider differencing as well as suitable transformation of the time series data to make it stationary. Both transformation and differencing are used for a non-stationary time series data on average monthly house prices to ensure it to be stationary. We then analyse the data and make prediction for the future values.
Dhaka Univ. J. Sci. 67(1): 21-26, 2019 (January)
Assessment of Wind Power Potential at the Chittagong Coastline in Bangladesh
Authors: Mazumder Gour Chand , Md Ibrahim Abu Shahadat , Shams SM Nasif , Huque Saiful 
Published: July 2021

A small wind data logger is used to record the wind speed for one year (2015 to 2016) at the Chittagong coastline in Bangladesh. A multi-storied building’s rooftop in Chittagong Export Processing Zone (CEPZ) is selected as a wind data collection site. The recorded data is analyzed using Weibull distribution functions. Three statistical methods are used to find and compare the Weibull parameters. Weibull probability density function and cumulative distribution are used to explain the recorded data. The analysis shows the shape factor of the site is 1.8 and the yearly scale factor is 2.2ms-1. The highest values of these parameters are found by calculation in the month of June when the maximum shape factor is 3 and the maximum yearly scale factor is 3.95 ms-1. To estimate yearly energy production three different wind turbine models ‘Aventa AV-7’, ‘Enercon E-33’ and ‘Enercon E-53’ are used and the estimation is done using a mathematical approach. The probable wind power production capacity of this site would be around 5457kWh per year and the energy density of this site would be around 11.54 kWhm-2. This research work may be helpful for the design and planning of any wind power plant at the Chittagong coastline area in Bangladesh.
Dhaka Univ. J. Sci. 67(1): 27-32, 2019 (January)
Integrated Study of Production Decline Analysis and Streamline Simulation on Haripur Oil Field
Authors: Islam Mohammad Amirul , Woobaidullah ASM , Imam Badrul 
Published: July 2021

In oil and gas industries there are available production data analysis tools and reservoir simulation techniques. Scientists and engineers use these tools and techniques to generate authentic and valuable information on the reservoir for planning and development. In this study production rate decline and streamline reservoir simulation are analyzed integrated way to determine the well life, flow rate, producible reserve, drainage volume and reserve. Well no SY-7 of Haripur oil field produced 0.531 million barrel of oil from 1987 to 1994. Exponential decline rate is matched with production profile and reveals well life of 10 years, producible reserve 0.7 million barrels. In addition, the drainage volume around the well is 158 million cubic feet estimated from the well life by using the streamline simulation, as well as the oil reserve 2 million barrels in the drainage volume is estimated. This reserve information carries value, authenticity and reliability for field development planning.
Dhaka Univ. J. Sci. 67(1): 47-50, 2019 (January)
The Role of Non-Linear Birth Functions on the Dynamics of Malaria Vector Population
Authors: Ovi Murshed Ahmed , Niger AM , Podder CN 
Published: July 2021

As mosquito vector plays a significant role in malaria dynamics, a deterministic delay differential equation model10 for the population dynamics of the malaria vector is rigorously analyzed for the non-delay part subject to a new form of vector birth rate function; the Hassell function. For the Hassell function, the model has a non-trivial equilibrium which is locally-asymptotically stable under certain conditions. It is also shown that the non-trivial equilibrium corresponding to this birth function bifurcates into a limit cycle via a Hopf bifurcation. The Maynard-Smith-Slatkin function is better than the Verhulst-Pearl logistic growth function as the former is associated with increased sustained oscillations 9. Again this Maynard- Smith-Slatkin function is more preferable than the Hassell function as the prior one is pertained to more sustained oscillations and holds the analyzed properties for the realistic size of the limiting birth rate.
Dhaka Univ. J. Sci. 67(1): 55-62, 2019 (January)
Hopf Bifurcation of the Higher Dimensional Hénon Map
Authors: Islam Saiful , Podder Chandra Nath 
Published: July 2021

In this paper, the discrete time generalized Hénon map is considered and the existence of Hopf bifurcation via an explicit criterion for N≥3, in particular for N=4 and N=5 has given. The relation between the parameters a and b as well as the range of the values of the parameters for N=3,4,5 has driven and the existence of Hopf bifurcation is demonstrated for the values of the parameters calculated from their relations. The results of numerical simulations for different values of the parameters are also presented.
Dhaka Univ. J. Sci. 67(1): 73-78, 2019 (January)
Determinants of Postnatal Care Utilization for the Newborns in Urban Slums of Bangladesh: A Study Based on Bangladesh Urban Health Survey Data
Authors: Islam Mirajul , Sultana Nasrin , Hasan Muhammad Mahmudul 
Published: July 2021

Better child health can be guaranteed by ensuring postnatal care for the newborns after birth. Newborns in the slums of Bangladesh are lagging behind to receive postnatal care and the percentage of newborns receiving health check-up from medically trained provider within first two months after birth is very low. The purpose of this study is to find out the potential determinants of receiving postnatal care from medically trained provider for slum newborns in Bangladesh. Data have been extracted from Bangladesh Urban Health Survey (UHS), 2013 to serve the purpose of the study. From regression analysis, it is found that antenatal care during pregnancy from medically trained provider, delivery by skilled birth attendant, economic status of the newborn family, education level and media exposure of mothers are significant factors associated with the uptake of postnatal care from medically trained provider for the newborns in slums.
Dhaka Univ. J. Sci. 67(1): 69-72, 2019 (January)
DFT and TD-DFT Study of [Tris(dithiolato)M]3- Complexes[M= Cr, Mn and Fe]: Electronic Structures, Properties and Analyses
Authors: Matin Mohammad A , Mohammad Alauddin - , Debnath Tapas , Islam M Saiful , Aziz Mohammed A 
Published: July 2021

Using Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods, transition metal complexes of benzene-1, 2-dithiolate (L2-) ligand from Cr to Fe have been studied theoretically. The ground state geometries, binding energies, UV-Visible spectra (UV-Vis), frontier molecular orbitals (FMOs) analysis, charge analysis and natural bond orbital (NBO) have been calculated. The structural parameters are in good accord with the experimental data. The metal-ligand binding energies are one (1) order of magnitude higher than the physisorption energy of a benzene-1, 2-dthiolate molecule on a metallic surface. In accordance with experiment the calculated electronic spectra of these tris complexes show bands at 565, 559 and 546 nm for Cr3+, Mn3+, and Fe3+ respectively which are mainly qualified to ligand-to metal charge transfer (LMCT) transitions. The electronic properties analysis demonstrate that the highest occupied molecular orbital (HOMO) is mostly centered on metal coordinated sulfur atoms whereas the lowest unoccupied molecular orbital (LUMO) is mainly located on the metal surface. By calculating natural bond orbital (NBO), the intramolecular interactions and electron delocalization was obtained. The results of NBO analysis illustrated the significant charge transfer from sulfur to central metal ions, as well as to the benzene of the complex. The calculated charges on metal ions are also reported at various charge schemes. The calculations show encouraging agreement with the available experimental data.
Dhaka Univ. J. Sci. 67(1): 63-68, 2019 (January)
Socio-economic and Demographic Risk Factors for Overweight or Obesity among Ever Married Women in Bangladesh: A Mixed Model Approach
Authors: Sultana Nasrin , Islam Mirajul 
Published: July 2021

Overweight or obesity has adverse effects on health as the risk of diabetes and cardiovascular disease is very high among overweight or obese women. Even mortality rate among overweight and obese people is more than that of normal or underweight people. The risk of facing adverse maternal and fetal complications during pregnancy, delivery, and postpartum is higher among overweight/obese women. In Bangladesh, the percentage of overweight/obesity among ever married women which was only 9 percent in 2004 was found to be 24 percent in 2014. The main purpose of the study is to determine the responsible factors for the overweight or obesity among ever married women aged 15-49 years in Bangladesh. Data have been taken out from Bangladesh Demographic and Health Survey (BDHS), 2014 to serve this purpose. Since there are 600 clusters in BDHS data, cluster effects are taken into account to find the estimates of the regression parameters by applying mixed logistic regression model. The results obtained from the model show that women from poor family (OR = 0.69), living in Rangpur (OR=0.83) and Sylhet regions (OR = 0.66), currently working (OR = 0.79) and using modern contraceptive (OR = 0.88) are significantly less overweight/obese than women from middle class family, living in Dhaka region, currently not working and using contraceptive except modern type, respectively. On the other hand, women from urban residence (OR = 1.54), having education and educated husband, women from rich family (OR = 1.63), married women (OR = 1.48), older age, watching TV at least once in a week (OR = 1.35) and having two or three ever born children (OR = 1.31) are more overweight/obese than their respective counterpart.
Dhaka Univ. J. Sci. 67(2): 85-90, 2019 (July)
A Comparison Study of Finding Efficient Methods for Generating Normal Random Numbers
Authors: Sajib Anamul Haque , Akter Syeda Fateha 
Published: July 2021

Normal distribution is one of the most commonly used non-uniform distributions in applications involving simulations. Advanced computing facilities make the simulation tasks simple but the challenge is to meet the increasingly stringent requirements on the statistical quality of the generated samples. In this paper, we examine performances of different existing methods available to generate random samples from normal distribution based on statistical quality of the generated samples (randomness and normality) and computational complexities. From the simulation study, it is observed that CDF approximation based method and acceptance-rejection method devised by Rao et al12 and Sigman14 are the fastest and the slowest respectively among all algorithms considered in this paper while generated samples produced by all methods satisfy randomness and normality properties. An application involving simulation from normal distribution is shown by considering a Monte Carlo integration problem.
Dhaka Univ. J. Sci. 67(2): 91-98, 2019 (July)
Determination of Optimal Smoothing Constants for Holt - Winter’s Multiplicative Method
Authors: Dhali Md Nayan , Barman Nandita , Hasan M Babul 
Published: July 2021

There are many trade time series parade having seasonality. This paper ponders on taking the appropriate smoothing constants of seasonal time series data using Holt-Winter’s exponential smoothing method in demand forecasting of toy production in a company. It is a quantitative technique in forecasting. This forecasting method is used three constants that assign weights to current demands and previous forecasts to decide on a new forecast. We have demonstrated the techniques how to choose these constants by presenting a real life example and calculated corresponding forecast value of this technique for the optimal smoothing constants.
Dhaka Univ. J. Sci. 67(2): 99-104, 2019 (July)
Model Selection Strategy for Cox Proportional Hazards Model
Authors: Farooq Fabiha Binte , Karami Md Jamil Hasan 
Published: July 2021

Often in survival regression modelling, not all predictors are relevant to the outcome variable. Discarding such irrelevant variables is very crucial in model selection. In this research, under Cox Proportional Hazards (PH) model we study different model selection criteria including Stepwise selection, Least Absolute Shrinkage and Selection Operator (LASSO), Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC) and the extended versions of AIC and BIC to the Cox model. The simulation study shows that varying censoring proportions and correlation coefficients among the covariates have great impact on the performances of the criteria to identify a true model. In the presence of high correlation among the covariates, the success rate for identifying the true model is higher for LASSO compared to other criteria. The extended version of BIC always shows better result than the traditional BIC. We have also applied these techniques to real world data.
Dhaka Univ. J. Sci. 67(2): 111-116, 2019 (July)
Analysis of Antenatal Care Visit Data in Bangladesh Using Zero Modified Count Regression Model
Authors: Ahmed Nasiba Maruf , Mallick Taslim Sazzad 
Published: July 2021

In medical science, pharmaceutical studies, public health and socio-economic researches we often encounter the situation of excess of zeros in count data. This preponderance of zeros leads to overdispersion. In such cases traditional count data regression models like Poisson and negative binomial (NB) regression may not be pertinent for inference. The two most commonly used types of model that have been developed to adjust for excessivezeros in count data are Hurdle and zero-inflated models. In this study we have analyzed the antenatal care (ANC) visit data of pregnant women in Bangladesh using traditional and zero-modified count models. Based on the model selection criteria, we found that negative binomial hurdle model fits the data best. Through this analysis,we have perceived that the variables age of mother, division, birth order (order a child is born), place of residence, economic condition, media exposure of the mother, mainaccess road to village and education gap between husband and wife have significant impact on the mean number of ANC visits taken.
Dhaka Univ. J. Sci. 67(2): 117-122, 2019 (July)
Efficient Generation of Gaussian Varaiates Via Acceptance-Rejection Framework
Authors: Sajib Anamul Haque 
Published: July 2021

The Gaussian distribution is often considered to be the underlying distribution of many observed samples for modelling purposes, and hence simulation from the Gaussian density is required to verify the fitted model. Several methods, most importantly, Box-Muller method, inverse transformation method and acceptance-rejection method devised by Box and Muller1, Rao et al.7 and Sigman8 respectively, are available in the literature to generate samples from the Gaussian distribution. Among these methods, Box-Muller method is the most popular and widely used because of its easy implementation and high efficiency,which produces exact samples2. However, generalizing this method for generating non-standard multivariate Gaussian variates is not discovered yet. On the other hand, inverse transformation method uses numerical approximation to the CDF of Gaussian density which may not be desirable in some situations while performance of acceptance-rejection method depends on choosing efficient proposal density. In this paper, we introduce a more general technique by exploiting the idea invented by Wakefield9 under acceptance rejection framework to generate one dimensional Gaussian variates, in which we don’t require to choose any proposal density and it can be extended easily for non-standard multivariate Gaussian density. The proposed method is compared to the existing acceptance-rejection method (Sigman8 method), and we have shown both mathematically and empirically that the proposed method performs better than Sigman8 method as it has a higher acceptance rate (79.53 %) compared to Sigman (76.04 %) method.
Dhaka Univ. J. Sci. 67(2): 123-130, 2019 (July)
Maternal Health Care Seeking Behavior in Urban Area of Bangladesh: Does Migration Create Inequity?
Authors: Sutopa Tasmiah Sad 
Published: July 2021

The main aim of this paper is to find potential sources that affect maternal health care seeking behavior of women of urban areas in period around the birth of their children using data extracted from Bangladesh Urban Health Survey 2013. To examine the maternal health care seeking behavior among women,antenatal care, place of delivery and postnatal care are considered as dependent variables and several demographic and socio-economic factors are included as independent variable. The study reveals that the recent migrant women and slum dwellers have a tendency of being disadvantaged in context of maternal health care. There is still plenty of room to work on maternal health care among women in urban areas especially among recent migrants so that significant improvement can be initialized to achieve an equity in overall health care system in Bangladesh.
Dhaka Univ. J. Sci. 67(2): 131-138, 2019 (July)
The Effects of Birth Spacing on Nutritional Status in the form of Stunting of Under Five Children in Bangladesh: Evidence Based on BDHS, 2014 Data
Authors: Khokan Mahfuzur Rahman 
Published: July 2021

In this paper, it has been examined the effect of preceding birth interval on nutritional status in the form of Stunting of the children aged under 5 years of age in Bangladesh.For the purpose of the analysis, Bangladesh Demographic and Health Survey (BDHS), 2014 data has been used. The study cases are the children under 5 years aged born during last delivery of their mother. The response variable is Nutritional Status of under 5 year children in the form of stunting. The key independent variables is the length of the preceding birth interval, measured as the number of months between the births of the child under study.Bivariate analysis along with a Chi-square test has been performed to examine the association between preceding birth interval and stunting of the children. To determine the effect of preceding birth interval, three different logistic regression models (Model-I: considering only the preceding birth intervals, Model-II: covariate of model-I along with demographic and socioeconomic factors and Model-III: covariates of model-II along with health related factors) were considered. The occurrence of stunting has been found to be inversely related with the preceding birth interval for the children aged under 5 years in Bangladesh. This inverse association has been found statistically significant for three models.After adjusting the demographic, socio-economic and health-related factors, the OR (odds ratio) shows that the percentage of being stunted is 73% higher for the children whose preceding birth interval is less than 24 (<24) while it is 37% higher for the children whose preceding birth interval is between months compared to whose birth interval is more than 60 (60>) months with 99% confidence interval (1.27, 2.36)***and (1.07, 1.45)***respectively.
Dhaka Univ. J. Sci. 67(2): 139-144, 2019 (July)
Study of Pre-Monsoon Thunderstorms and Associated Thermodynamic Features Over Bangladesh Using WRF-ARW Model
Authors: Paul Pappu , Imran Ashik , Islam Md Jafrul , Kabir Alamgir , Jaman Sahadat , Syed Ishtiaque M 
Published: July 2021

Thunderstorm is a mesoscale system (from a km to below thousands of km and sustaining less than one hour). Two pre-monsoon thunderstorms events are analyzed in this study which are named as event-1 (0030-0150 UTC of 19 April 2018 over Chattogram) and event-2 (0600-1000 UTC of 4 May 2018 over Dhaka). To predict these events Mean Convective Available Potential Energy (mCAPE), Mean Convective Inhibition Energy (mCINE), K Index (KI), Total totals Index (TTI), wind distribution, and relative humidity (RH) are investigated.The model simulated mCAPE and mCINE values, 18 hours before the events, are found greater than 1700 J/Kg and less than 100 J/Kg respectively which satisfies the conditions for thunderstorms to occur.The KI values are close to 400C and TTI values are greater or equal to 450C for both events. The wind patterns and the high value of mid –tropospheric RH also favors the formation of severe thunderstorm.
Dhaka Univ. J. Sci. 67(2): 151-156, 2019 (July)
Study of Graded Algebras and General Linear Group with Lie Superalgebras and R-Algebra
Authors: Ahmed Khondokar M , Rasel SK , Das Jyoti , Tahura Saraban , Nasrin Salma 
Published: July 2021

Some elements of theory of Z2 graded rings, modules and algebras. Z2-graded tensor algebra, Lie superalgrbras and matrices with entries in a Z2-graded commutative ring are treated in our present paper. At last a Theorem 4.4.on the set of square matrices in the graded R-algebra , MR-[m I n] is established.
Dhaka Univ. J. Sci. 68(1): 1-5, 2020 (January)
Analyzing Malnutrition Among Children of Urban Areas in Bangladesh: Penalized Logistic Regression Model
Authors: Kanon Naito , Bari Wasimul 
Published: July 2021

This paper focused on the analysis of malnutrition of the children of Bangladesh urban areas in the presence of multicollinearity among the covariates. The ridge regression has been adopted under binary logistic model for analyzing malnutrition data extracted from Bangladesh Urban Health Survey 2013 (UHS 2013) dataset. The study reveals that city corporation slum area, mother’s age at birth, gender of child, birth order number, age of child, wealth index, mother’s education, access to media, toilet facility at household, taking antenatal care service, and place of delivery of index child have significant impact on the nutritional status of urban children of Bangladesh. Some recommendations have been suggested for policy makers to improve the child health of urban areas in Bangladesh.
Dhaka Univ. J. Sci. 68(1): 13-18, 2020 (January)