bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying an Appropriate Forecasting Technique for Predicting Future Demand: A Case Study on a Private University of Bangladesh
Authors: Suraiya Sayma , Hasan M Babul
Published: July 2021

Demand forecasting and inventory control of printing paper is crucial that is frequently used every day for the different purposes in all sectors of educational area especially in Universities. A case study is conducted in a University store house to collect all historical demand data of printing papers for last 6 years (18 trimesters), from January (Spring) 2011 to December (Fall) 2016. We will use the different models of time series forecasting which always offers a steady base-level forecast and is good at handling regular demand patterns. The aim of the research paper is to find out the less and best error free forecasting techniques for the demand of printing paper for a particular time being by using the quantitative forecasting or time series forecasting models like weighted moving average, 3-point single moving average, 3-point double moving average, 5-point moving average, exponential smoothing, regression analysis/linear trend, Holt’s method and Winter’s method. According to the forecasting error measurement, we will observe in this research that the best forecasting technique is linear trend model. By using the quantities of data and drawing the conclusion with an acceptable accuracy, our analysis will help the university to decide how much inventory is absolutely needed for the planning horizon.

Dhaka Univ. J. Sci. 66(1): 15-19, 2018 (January)
Utilization of Antenatal Care, Skilled Birth Assistant and Institutional Delivery in Bangladesh
Authors: Nabeen AHM Musfiqur Rahman , Jannat Nur E , Akanda Md Abdus Salam
Published: July 2021

Maternal mortality is an important phenomenon to assess the overall health status of a society. To reduce maternal mortality the worldwide recognized vital three factors are: antenatal care, presence of skilled birth assistance and selection of place of delivery. This study made an initiative to identify potential risk factors which can influence the three factors employing the Bangladesh Demographic and Health Survey (BDHS), 2014 data. The parameters are estimated using Poisson count model and Logistic regression model. The estimation results indicate that mother’s education level, place of residence, mother’s age at birth, wealth index, husband’s education level, media exposure and region are significant factors for antenatal care visits. The significant factors for skilled birth assistance are mother’s education level, place of residence, wealth index, media exposure and husband’s education level where as place of residence, mother’s education level, wealth index, media exposure and husband’s education level are significant factors for selection of place of delivery. These results may help the policy makers to develop policies that may facilitate the reduction of maternal mortality in Bangladesh.

Dhaka Univ. J. Sci. 66(1): 21-27, 2018 (January)
Simulation of Monsoon Low Pressure System and its Associated Rainfall Over Bangladesh Using WRF Model
Authors: Roy Deepa , Samad Md Abdus , Hassan SM Quamrul
Published: July 2021

In this paper an effort has been made to simulate the monsoon Low Pressure System (LPS) and its associated rainfall event of 16-20 August, 2013 using Weather Research and Forecasting (WRF) model. The model was run for 24-h, 48-h and 72-h in a single domain of 10 km horizontal resolution using The National Centre for Environmental Prediction (NCEP) high-resolution Global Final (FNL) Analysis 6-hourly data using initial and lateral boundary conditions. WRF double-moment 5 class micro physics scheme, Kain–Fritsch (new Eta) cumulus physics scheme,Yonsei University planetary boundary layer scheme, Revised MM5 surface layer physics scheme, Unified Noah LSM as land surface model, Rapid Radiative Transfer Model (RRTM) for long-wave and Dudhia scheme for short-wave scheme are used for the simulation. The performance of the model is evaluated analyzing Mean Sea Level Pressure (MSLP), Wind Pattern, Vorticity, Vertical Wind Shear and Rainfall Distribution. The model successfully captured the low pressure system, initial condition, propagation, landfall time and location reasonably well. The model simulated rainfall amount and associated areas sensibly well compared with the observed data by BMD and Tropical Rainfall Measuring Mission (TRMM).

Dhaka Univ. J. Sci. 66(1): 29-35, 2018 (January)
Sedimentological and Palynological Approach for Determining the Depositional Environment of the Outcropping Surma Group Mudrocks in the Sitakund Anticline, Chittagong-Tripura Fold Belt, Bangladesh
Authors: Gazi Md Yousuf , Saha Subrota Kumar , Kabir SM Mainul , Imam Md Badrul
Published: July 2021

Sitakund anticlinal structure exposes about 1.5 km of Surma group sediments and has been chosen for a comprehensive study of the mudrocks depositional environment based on sedimentological and palynological evidences. Five mudrock facies have been identified in this region. They are Mudstone Dominated, Sand/Silt Streaked Shale, Fissile Shale, Laminated Shale and Lenticular Bedded Shale. The palynological assemblages from these samples have been analyzed qualitatively, and a variety of pollen, spores, algae and fungi identified. The pollen and spores have been attributed to parent plants located at the immediate and more regional surrounding areas during the deposition of these sediments. Palynological assemblages incorporates ample of Palmae grains such as spores in the Palmipollenites and Proxaperites and predominance of pteridophytic spores. The occurrences and abundances of these pollens indicate that the deposition of the Surma mudrocks took place at the proximity of the shore level. Coastal fluvial environment is also triumphed after the previous depositional event which is apparent by the occurrence of palynomorphs of pteridophytes, angiosperms and algal origin.

Dhaka Univ. J. Sci. 66(1): 37-42, 2018 (January)
Influences of Proximate Determinates on Fertility Among Urban and Rural Women in Bangladesh
Authors: Hasan Muhammad Mahmudul , Islam Mirajul , Sakib Md Saifullah , Haq Md Iqramul
Published: July 2021

Bangladesh has met a lot of challenges in recent decades. The remarkable decline in fertility is one of the major challenges faced by this country. The rate of fertility in rural areas is still higher than urban areas. The proximate determinants of fertility which influence fertility directly are analyzed in this study for urban and rural areas separately as well as the study quantify the decomposition of the differences in total fertility rate (TFR) in residence during 1993-94 to 2014. The effectiveness of contraceptive use is found to be the most important factor for declining fertility. The result revealed that the index of contraception shows a declining trend, indicating an increasingly inhibiting effect on fertility in both urban and rural areas of Bangladesh. The inhibition effect of postpartum infecundability decreases with increase in urbanization. The decomposition analysis shows that fertility decline has been occurred due to delay marriage, increase of contraception practice, shortening of postpartum infecundability period, increase proportion in induced abortion and the interaction factor.

Dhaka Univ. J. Sci. 66(1): 49-54, 2018 (January)
Advising an Appropriate Forecasting Method for a Snacks Item (Biscuit) Manufacture Company in Bangladesh
Authors: Barman Nandita , Hasan M Babul , Dhali Md Nayan
Published: July 2021

In this paper, we study the most appropriate short-term forecasting methods for the newly launched biscuit factory produces different types of biscuits. One of them is nut-orange twisted biscuits. As it is a newly launched biscuit factory, it does not use any scientific method to find future demand of their products to produce for the purpose of sales. Having an error free production as well as a good inventory management we try to find an appropriate forecasting method for the sets of data we analyzed for that specific production. Several forecasting methods of time series forecasting such as the Moving Averages, Linear Regression with Time, Exponential Smoothing, Holt‘s Method, Holt-Winter‘s Method etc. can be applied to estimate the demand and supply for these companies. This paper focuses on selecting an appropriate forecasting technique for the newly launched biscuit company. For this, we analyze Exponential Smoothing method as used to time series. We observe from the empirical results of the analysis that if the data has no trend as well as seasonality, Exponential Smoothing Forecasting Method processes as the most appropriate forecasting method for the factory. If the data experiences linear trend in it then Holt’s Forecasting Method processes as the most appropriate forecasting method for the sets of data we analyzed.

Dhaka Univ. J. Sci. 66(1): 55-58, 2018 (January)
A DFT Investigation of Tris-(4´-(Amino)(1,1´-biphenyl)-3,4-diol) Fe(III) Complex
Authors: Matin Mohammad A , Aziz Mohammed A , Islam M Saiful
Published: July 2021

Phenolic compounds, known as the pyrocatechol act as a metal chelating agent. Molecular details of cross-linking of pyrocatechol by transition metal ions are largely unknown. In the present study, the molecular properties of the tris-(4´-(amino)(1,1´-biphenyl)-3,4-diol)- Fe(III) complex have been investigated using density functional theory (DFT) at 6-311G(d,p). Calculated molecular properties of the optimized structure, the binding energies and spectroscopic properties are compared with the available experimental results. For the tris-complex investigated, the binding of Fe (III) with the catechol derivative is not as strong as the binding of other metal ions with catechol. The IR stretching bands show that the strong IR intensities is due to large charge polarization. Calculated electronic band gap is 2.45 eV which is in the range of transition metal ion-tris-(4´-(amino)(1,1´-biphenyl)-3,4-diol) complexes. The metal-ligand binding energy is 513.54 kcal mol-1, which could be used in understanding the speciation of Fe(III)-catechol complex. Structural parameters obtained from the DFT calculations are in good agreement with the crystallographic data.

Dhaka Univ. J. Sci. 66(1): 67-71, 2018 (January)
Structure Analysis of Tropical Cyclone Hudhud Over Bay of Bengal Using WRF Model
Authors: Imran Ashik , Syed Ishtiaque M , Hassan SM Quamrul , Rahman Kh Hafizur
Published: July 2021

Tropical cyclones (TCs) over Bay of Bengal (BoB) have significant socio-economic impacts on the countries bordering the BoB. In this study, we have examined the structure and thermodynamic features of the TC Hudhud (7th -14th October, 2014) using WRF model. Simulated outputs are in good agreement with the available observations of India Meteorological Department and Joint Typhoon warning Center. At maximum intensity stage, the system’s horizontal size is found around 690 km. Wind and vorticity distributions capture the circulation of the system very well. Most strong winds of 60 ms−1 are extended vertically from 850 hPa to about 700 hPa. Simulation has shown intensification of the system above 200 hPa with wind speed of about 30ms−1. Relative humidity of the order of 90 % is found up to 400 hPa.

Dhaka Univ. J. Sci. 66(1): 79-86, 2018 (January)
Commercial Shrimp Farming at Coastal Areas in Bangladesh and Its Effects on Livelihood and Environment: A Study on Paikgacha Upazila, Khulna
Authors: Md Mohiuddin - , Nowreen Samshad , Uchinlayen -
Published: July 2021

The study focuses on the changing livelihood pattern and the environment through shrimp farming in Bangladesh where the country is one of the largest producers of shrimp in the whole world. Shrimp production sector is contributing to the national economy of Bangladesh very fast other than any other sectors. This sector is the second top production sector of the century. This study was based on survey method; especially survey was done by questionnaire survey, where the primary data were collected from questionnaire survey. Although the environmental impact of shrimp cultivation is very adverse, the sector is becoming more popular because of huge profit. Therefore, the study found the change in pattern along with occupation, land use practice, sources of food, specially protein intake, transportation etc. Furthermore, the study found the adverse impact of intruding brackish water on surrounding environment and both on flora and fauna.

Dhaka Univ. J. Sci. 66(2): 87-90, 2018 (July)
Comparison Between ARIMA and VAR Model Regarding the Forecasting of the Price of Jute Goods in Bangladesh
Authors: Parvin Shahanaj , Khanam Murshida
Published: July 2021

In this study we used Autoregrressive Intigrated Moving Average (ARIMA) and Vector Autoregrressive (VAR) model to analyze and forecast the price of total Jute Goods with four of its types, where data has been collected from Bangladesh Jute Mills Corporation (BJMC) from the year 1980-81 to 2013-2014. In this study, a comparison has been made regarding ARIMA model and VAR model to investigate which model is the best to forecast. The methodology employed in this study is the co-integration and Granger Causality under VECM. The Augmented Dickey Fuller (ADF) Test has been performed to test the stationarity of the data set. The findings of this study suggested that in forecasting the price of jute goods of Bangladesh, the ARIMA model is more efficient than VAR model.

Dhaka Univ. J. Sci. 66(2): 91-94, 2018 (July)
A Case Study of Double Lid Driven Cavity for Low Reynolds Number Flow
Authors: Pal Doli Rani , Saha Goutam , Saha Kajal Chandra
Published: July 2021

The present numerical study has been accomplished remembering the true objective to explore the low Reynolds number flow with heat exchange behaviors inside a double lid driven square shaped cavity loaded with fluids such as air and water. Specifically, this work explores laminar, steady, incompressible mixed convection flow inside the cavity which has been done numerically by applying Finite Difference Method (FDM). In this analysis, top wall is treated as the heated wall and remaining walls are considered as cold walls. In addition, vertical side walls are moving at a relentless speed in its own particular plane along with the positive direction. Moreover, the numerical simulation is being conveyed out to observe the behavior of flow and thermal fields for variation of low Reynolds Number (Re), Richardson number (Ri) and Prandtl number(Pr). Also, the results have been validated through a comparison with other research works and a good agreement is observed. Also, results show that the above mentioned dimensionless parameters have significant effects on the flow and heat exchange attributes. Moreover, the effects of these parameters on average Nusselt number (Nu) have been analyzed and presented.

Dhaka Univ. J. Sci. 66(2): 95-101, 2018 (July)
Comparative Performance Study of Perovskite Solar Cell for Different Electron Transport Materials
Authors: Sultana Najmin Ara , Islam Md Obidul , Hossain Mainul , Mahmood Zahid Hasan
Published: July 2021

In recent times, planar organo-metal halide perovskite solar cells (PSCs) achieved high power conversion efficiency (PCE > 22%). Mixed organic-inorganic halide perovskites, with excellent light harvesting properties, have evolved as a promising class of semiconductors for photovoltaics. In this work, compositional and electrical characterizations of materials used for different layers of PSC have been studied. One dimensional solar cell simulator wx-AMPS is used for numerical simulation of such devices and all simulations are done under AM1.5 illuminations and 300K temperature. Investigating the influences of thickness of electron transport material (ETM), hole transporting material (HTM) and absorber on the photovoltaic performance of PSCs, it is observed that, increase in thickness of perovskite (MAPbI3) results in the increase in PCE of solar cells, whereas increase in thickness of ETM layer results in decrease in the efficiency of the devices. The ETM plays a vital role on the performance of PSC. In this paper, for the first time performances of PSC for three different ETMs (TiO2, ZnO or SnO2) are calculated and analyzed simultaneously with the simulator wx-AMPS. The photovoltaic performances have been explored and efficiencies of 27.6%, 27.5% and 28.02% are reported for perovskite solar cells with TiO2, ZnO and SnO2 as ETM respectively for a specific thickness. Finally, this simulation study concludes that ZnO and SnO2 may be effective alternatives of the commonly used material, TiO2 as they are economically more potential and give somewhat better photovoltaic performance.

Dhaka Univ. J. Sci. 66(2): 109-114, 2018 (July)
Performance Evaluation of Spectrum Sharing Methods in WiMAX/WiFi Integrated Networks
Authors: Chowdhury Mohammed Nowaz Rabbani , Mawa Jannatul , Aditya Subrata Kumar
Published: July 2021

Next generation wireless communication system is influenced by different wireless technologies such as WiFi, WiMAX, Cellular and LTE which use their fixed allocated spectrum. However, lack of spectrum resources becomes an important problem for future wireless network. Hence, for efficient use of spectrum resources, spectrum sharing between the existing wireless technologies receives much attention. However, to share the spectrum more efficiently, an effective spectrum sharing method should be developed. Most of the spectrum sharing methods are based on an optimization algorithm that provides an optimal solution for spectrum sharing. In this paper, the performance of a spectrum sharing method based on Genetic Algorithm (GA) has been evaluated. The method was applied in a WiMAX/WiFi integrated network, where a WiFi system temporarily uses a spectrum band of WiMAX system. Also a Linear Programming (LP) model has been developed as an alternative for spectrum sharing in the same network and comparative analysis between these two methods reveals that both methods give better performance in terms of throughput (bits/sec), download response time (sec) and received traffic rate (bytes/sec). According to the simulation results, it has been found that Genetic Algorithm (GA) shows its effectiveness in spectrum sharing in WiMAX/WiFi integrated network by reaching the global maxima very fast.

Dhaka Univ. J. Sci. 66(2): 103-107, 2018 (July)
A Comparative Study for Adsorptive Removal of Remazol Red R and Remazol Black B from Aqueous Solution by ZnO
Authors: Mazumder AZM Mainul Islam , Bikash Chowdhury Raihan , Rahman Md Ataur , Hossain Md Mufazzal
Published: July 2021

Adsorptive removal of remazol red R (RRR) and remazol black B (RBB) from aqueous solution has been investigated by using ZnO as an adsorbent. Time for adsorption equilibrium, kinetics of adsorption at different initial concentrations of dyes and adsorption isotherms at different temperatures have been studied. Adsorption capacity increased with increasing initial dye concentration. The pseudo first-order and pseudo second-order kinetics were used to describe kinetic data and the rate constants were evaluated. Experimental data fits better in the pseudo second-order kinetic model than in the pseudo first-order kinetic model for both the dyes. Langmuir and Freundlich isotherm models were applied to describe the adsorption of RRR and RBB onto ZnO powders. Langmuir isotherm model provided a better correlation for the experimental data in comparison to the Freundlich isotherm model. Adsorption of both RRR and RBB on ZnO are physical in nature and increases with decreasing temperature. The equilibrium adsorption capacity decreases from 3.43 mg/g at 200C to 2.36 mg/g at 400C for RRR whereas that in the case of RBB changes from 0.77 mg/g at 300C to 0.75 mg/g at 400C. Adsorption of RRR on ZnO was found to be three times higher than the adsorption of RBB at a particular temperature. A model for adsorption of both the dyes has been proposed.

Dhaka Univ. J. Sci. 66(2): 121-127, 2018 (July)
Socio-economic and Demographic Determinants of Women’s Household Decision Making Autonomy in Bangladesh: A Cross-sectional Study
Authors: Sen Kanchan Kumar , Islam Mirajul , Hasan Muhammad Mahmudul
Published: July 2021

Women’s autonomy is an important element of the economic and reproductive health developments in a country. The aim of this study was to find out the potential factors associated with women’s decision-making autonomy in Bangladesh. To fulfill this purpose, the cross-sectional data obtained from the Bangladesh Demographic Health Survey (BDHS), 2014 was used. The generalized linear mixed model approach has been applied to calculate the adjusted effects of the covariates by taking into account the correlation among subjects within clusters. The study reveals that women with age at marriage ≥ 18 years, having family size ≤ 4, having at least one child, exposed to media, belonging to NGO, living in urban areas and working outside home have greater influence on autonomy in household decision making.

Dhaka Univ. J. Sci. 66(2): 115-120, 2018 (July)
Women’s Empowerment and Its Determinants in Bangladesh: Evidence from a National Survey
Authors: Sen Kanchan Kumar , Nilima Shahnaz
Published: July 2021

The potential factors associated with women‟s empowerment in household decision making as well as attitudes toward wife beating were determined in the study. The Bangladesh Demographic Health Survey (BDHS), 2014 data were used to get the determinants of women‟s empowerment. To measure the women‟s empowerment, the principal component analysis was used in the study. The ordinal logistic regression model was applied to determine the potential factors for women‟s empowerment. Results were also compared with the results obtained from classical linear regression model. The study revealed that lower difference of spousal ages and lower number of daughters were more likely to increase women‟s empowerment. Similar to other studies, early marriage and living in rural area gave the women lower empowerment but education, 1-4 family members, having at least one child, exposed to media, belonging to NGO and working outside home had greater positive influence on women‟s empowerment.

Dhaka Univ. J. Sci. 66(2): 129-134, 2018 (July)
Spectrophotometric Analysis of Preservatives and Coloring Agents in Orange Soft Drink and Orange Juice Samples
Authors: Bhuyian Saiful Islam , Ahmed Tofael , Hasan M Kamrul , Mohammad Shoeb - , Nahar Nilufar
Published: July 2021

A rapid and simple UV-Vis spectrophotometric method was used for the determination of the level of sodium benzoate and yellow 6 in 14 different batches of orange soft drink samples and 7 different batches of orange juice samples commercially available in local markets of Bangladesh. The standard samples of sodium benzoate and yellow 6 in water were used to make calibration curves and the correlation coefficient (r2) of the calibration curves were found to be 0.9993 and 0.9953 for sodium benzoate and yellow 6, respectively. The wavelength of absorption maxima was 225 nm for Sodium benzoate and 429 nm for yellow 6. All 14 analyzed soft drinks samples contained yellow 6 and sodium benzoate in the range of 2.90-162.51 mg/L and 94.06-387.66 mg/L, respectively. The highest amount of sodium benzoate and yellow 6 were found in the sample AMR (387.66 mg/L) and BRC (162.51 mg/L), respectively. Among the 7 orange juice samples yellow 6 were found in the range of 28.03-102.66 mg/L and the highest amount was in the sample OJ1 (102.66 mg/L). The reproducibility and repeatability of the method was very satisfactory with low value of RSD in a range of 0.05 to 4.17% and 0.05 to 4.07%, respectively.

Dhaka Univ. J. Sci. 66(2): 135-137, 2018 (July)
Theoretical Investigation of Non-Linear Optical (NLO) Properties and UV-Visible Spectra of N-(3, 5-dichlorobenzylidene)aniline and N-(3, 5- dichlorobenzylidene)4-nitroaniline
Authors: Islam Md Saiful , Mousume Nusrat , Hossain M Mufazzal , Aziz Mohammed A , Islam M Saiful
Published: July 2021

The non-linear optical properties of two Schiff bases, N-(3,5-dichlorobenzylidene)aniline (A) and N-(3,5- dichlorobenzylidene)4-nitroaniline (B) have been studied by ab initio Hartree-Fock method using 6-311G (d,p) basis set. In this study, we report the dipole moment (μ), polarizability ( ) and hyperpolarizability (ß) of both compounds. The hyperpolarizability (ß) value of B is much greater than that of the compound A as it is expected because of the strong intramolecular charge-transfer interaction. The geometrical parameters of the optimized structure of both A and B are reported here and compared with the available experimental data of the relevant compounds. We also calculated the λmax values of compounds A and B. The UV-visible spectra show that both compounds are transparent in the visible region (> 400 nm), implying non-zero microscopic hyperpolarizability. All calculations have been performed using GAUSSIAN09 programme.

Dhaka Univ. J. Sci. 66(2): 139-143, 2018 (July)
Isolation and Characterization of Two Cucurbitane Type Triterpenoid Glycocide from 1-Butanol Soluble Part of Momordica charantia Fruit Pulp Juice
Authors: Hossain M Shakhawoat , Hasan M Kamrul , Shoeb M , Mamun MIR , Nahar N , M Mosihuzzaman -
Published: July 2021

Momordica charantia is a member of the Cucurbitaceae family having diverse biological activities. Two cucurbitane type triterpene glycoside have been isolated from 1-butanol soluble part of clear juice of M. charantia fruit pulp through column chromatography and HPLC. The isolated compounds were characterized as compound MC1 (3β, 7-O-β-glucopyranosyl-25-methoxy cucurbita –5-en-19-al) and compound MC2 (5β, 19-epoxy- 3- O-glucopyranosyl-25 methoxy cucurbita-6, 23-dien) with the help of UV Spectroscopy, Thin Layer Chromatography, IR Spectroscopy, 1H, 13C and dept-135 NMR. The proposed structures of the compounds were further confirmed by comparing the 13C-NMR values of the compounds with previous reported data.

Dhaka Univ. J. Sci. 66(2): 145-149, 2018 (July)
Cu(II), Zn(II), Cd(II) and Hg(II) Complexes of Pantroprazole (PPZH): Synthesis and Characterization
Authors: Begum Salma , Yeasmin Humaira , Shaikh AA , Bakshi Pradip K
Published: July 2021

Several metal complexes of pantoprazole, [Cu(PPZ)(H2O)Cl], [Zn(PPZ)2], [Cd(PPZ)2].1.5H2O and [Hg(PPZ)(H2O)Cl] have been synthesized and characterized. Elemental analysis, IR, UV-Visible spectral analysis, magnetic measurement, thermogravimetric analysis, differential scanning calorimetric and cyclic voltammetric techniques were used for their characterization. The lipophilic weak base pantoprazole (PPZ) act as a potential bidentate ligand forming coordination complexes with divalent metal ions through anionic imidazolyl N- and O atom of sulfinyl >S=O group. All complexes possess tetrahedral geometry.

Dhaka Univ. J. Sci. 66(2): 151-156, 2018 (July)
Electromagnetics in Terms of Differential Forms
Authors: Hena Hasna , Jahangir Jenita , Ali Md Showkat
Published: July 2021

The calculus of differential forms has been applied to electromagnetic field theory in several papers and texts, some of which are cited in the references. Differential forms are underused in applied electromagnetic research. Differential forms represent unique visual appliance with graphical apprehension of electromagnetic fields. We study the calculus of differential forms and other fundamental principle of electromagnetic field theory. We hope to show in this paper that differential forms make Maxwell’s laws and some of their basic applications more intuitive and are a natural and powerful research tool in applied electromagnetics.

Dhaka Univ. J. Sci. 67(1): 1-4, 2019 (January)
Conjugate Effects of Thermal and Mass Diffusion on Natural Convection Flow from a Heated Sphere with Internal Heat Generation or Absorption
Authors: Masud Sadia , Roy Nepal Chandra
Published: July 2021

We examine the conjugate effects of thermal and mass diffusion on the unsteady natural convection flow from a heated sphere. The mathematical model of the problem is made into a system of nonsimilar partial differential equations introducing appropriate transformations. We solve this system employing the implicit finite difference technique. Numerical solutions have been elucidated with the skin friction as well as heat and mass transfer for varying Prandtl number, Schmidt number, combined buoyancy parameter, and heat generation or absorption parameter.

Dhaka Univ. J. Sci. 67(1): 13-20, 2019 (January)
Numerical Solutions of Time Dependent Partial Differential Equations Using Weighted Residual Method With Piecewise Polynomials
Authors: Alam Muntasir , Islam Md Shafiqul
Published: July 2021

We use Galerkin weighted residual (GWR) method to solve one dimensional heat and wave equations as initial and boundary value problems (IBVPs) numerically. Three special types of piecewise polynomials namely: Bernstein, Bernoulli and Legendre polynomials are used as basis functions to solve these IBVPs. A few examples are tested by the proposed method and then the results are compared with the solutions found in other existing methods. The numerical results obtained in this paper are in good agreement with the exact solutions.

Dhaka Univ. J. Sci. 67(1): 5-12, 2019 (January)
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)