Pub Date : 2019-07-30DOI: 10.3329/dujs.v67i2.54578
N. Sultana, Mirajul Islam
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)
{"title":"Socio-economic and Demographic Risk Factors for Overweight or Obesity among Ever Married Women in Bangladesh: A Mixed Model Approach","authors":"N. Sultana, Mirajul Islam","doi":"10.3329/dujs.v67i2.54578","DOIUrl":"https://doi.org/10.3329/dujs.v67i2.54578","url":null,"abstract":"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. \u0000Dhaka Univ. J. Sci. 67(2): 85-90, 2019 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77572618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-30DOI: 10.3329/dujs.v67i2.54582
Fabiha Binte Farooq, Md Jamil Hasan Karami
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)
{"title":"Model Selection Strategy for Cox Proportional Hazards Model","authors":"Fabiha Binte Farooq, Md Jamil Hasan Karami","doi":"10.3329/dujs.v67i2.54582","DOIUrl":"https://doi.org/10.3329/dujs.v67i2.54582","url":null,"abstract":"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. \u0000Dhaka Univ. J. Sci. 67(2): 111-116, 2019 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"2016 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73326829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-30DOI: 10.3329/dujs.v67i2.54589
Pappu Paul, A. Imran, Md. Jafrul Islam, Alamgir Kabir, Sahadat Jaman, I. M. Syed
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)
{"title":"Study of Pre-Monsoon Thunderstorms and Associated Thermodynamic Features Over Bangladesh Using WRF-ARW Model","authors":"Pappu Paul, A. Imran, Md. Jafrul Islam, Alamgir Kabir, Sahadat Jaman, I. M. Syed","doi":"10.3329/dujs.v67i2.54589","DOIUrl":"https://doi.org/10.3329/dujs.v67i2.54589","url":null,"abstract":"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. \u0000Dhaka Univ. J. Sci. 67(2): 151-156, 2019 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87300722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-30DOI: 10.3329/dujs.v67i2.54584
A. Sajib
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)
{"title":"Efficient Generation of Gaussian Varaiates Via Acceptance-Rejection Framework","authors":"A. Sajib","doi":"10.3329/dujs.v67i2.54584","DOIUrl":"https://doi.org/10.3329/dujs.v67i2.54584","url":null,"abstract":"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. \u0000Dhaka Univ. J. Sci. 67(2): 123-130, 2019 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75148629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-30DOI: 10.3329/dujs.v67i2.54579
A. Sajib, Syeda Fateha Akter
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)
正态分布是模拟应用中最常用的非均匀分布之一。先进的计算设施使模拟任务变得简单，但挑战在于如何满足对生成样本的统计质量日益严格的要求。在本文中，我们根据生成样本的统计质量(随机性和正态性)和计算复杂性，研究了不同现有方法的性能，这些方法可用于从正态分布中生成随机样本。从仿真研究中可以看出，基于CDF近似的方法和由Rao et al12和Sigman14设计的接受-拒绝方法在本文所考虑的所有算法中分别是最快和最慢的，并且所有方法产生的生成样本都满足随机性和正态性。通过考虑蒙特卡罗积分问题，给出了一个涉及正态分布模拟的应用。达卡大学学报(自然科学版)，67(2):91- 98,2019 (7)
{"title":"A Comparison Study of Finding Efficient Methods for Generating Normal Random Numbers","authors":"A. Sajib, Syeda Fateha Akter","doi":"10.3329/dujs.v67i2.54579","DOIUrl":"https://doi.org/10.3329/dujs.v67i2.54579","url":null,"abstract":"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. \u0000Dhaka Univ. J. Sci. 67(2): 91-98, 2019 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"159 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86990152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-30DOI: 10.3329/dujs.v67i2.54581
A. Hossain, Maliha Tasmiah Noushin, Kamrul Hasan
In this paper we estimate European put option price by using awell-established option pricing model, namely, the Constant Elasticity of Variance (CEV) model for the elasticity parameter β< 2 and then compare it with the benchmark Black-Scholes (BS) model. We calculate the Greeks under the CEV model for β=0,1 and 1.95 and compare them with that of the B-S one. Finally, we investigate the put price and Greeks values for at-the-money (ATM), in-the-money (ITM) and out-of-the-money (OTM) situations. Dhaka Univ. J. Sci. 67(2): 105-110, 2019 (July)
{"title":"A Comparison of the Black-Scholes Option Pricing Model and Its Alternatives","authors":"A. Hossain, Maliha Tasmiah Noushin, Kamrul Hasan","doi":"10.3329/dujs.v67i2.54581","DOIUrl":"https://doi.org/10.3329/dujs.v67i2.54581","url":null,"abstract":"In this paper we estimate European put option price by using awell-established option pricing model, namely, the Constant Elasticity of Variance (CEV) model for the elasticity parameter β< 2 and then compare it with the benchmark Black-Scholes (BS) model. We calculate the Greeks under the CEV model for β=0,1 and 1.95 and compare them with that of the B-S one. Finally, we investigate the put price and Greeks values for at-the-money (ATM), in-the-money (ITM) and out-of-the-money (OTM) situations. \u0000Dhaka Univ. J. Sci. 67(2): 105-110, 2019 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81536809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-30DOI: 10.3329/dujs.v67i1.54572
M. Alauddin, T. Debnath, M. Aziz
It is well known that stability of deoxyribo-nucleic acid (DNA) double helix depends on hydrogen bonding (HB) between adenine-thymine and guanine-cytosine. HB plays an important role in molecular systems, particularly in biological systems because all lives on the earth may be viewed as a matter of hydrogen-bonding supramolecular systems. Since HBs have a central role on the mechanism of life phenomena including the structure and functions, it is essential to understand the molecular-level aspects of HB systems. Therefore, we studied the structural properties of adenine-thymine (A-T) basepair theoretically using DFT/B3LYP/6-31G level of theory. Theoretically we found four isomers of A-T basepair and the most stable isomer is one in which adenine and thymine are connected via two hydrogen bonding. The electronic properties were calculated by Time Dependent Density Functional Theory (TD-DFT) approach. Dhaka Univ. J. Sci. 67(1): 51-54, 2019 (January)
{"title":"Structural and Electronic Properties of Adenine-Thymine Basepair : A Computational Study","authors":"M. Alauddin, T. Debnath, M. Aziz","doi":"10.3329/dujs.v67i1.54572","DOIUrl":"https://doi.org/10.3329/dujs.v67i1.54572","url":null,"abstract":"It is well known that stability of deoxyribo-nucleic acid (DNA) double helix depends on hydrogen bonding (HB) between adenine-thymine and guanine-cytosine. HB plays an important role in molecular systems, particularly in biological systems because all lives on the earth may be viewed as a matter of hydrogen-bonding supramolecular systems. Since HBs have a central role on the mechanism of life phenomena including the structure and functions, it is essential to understand the molecular-level aspects of HB systems. Therefore, we studied the structural properties of adenine-thymine (A-T) basepair theoretically using DFT/B3LYP/6-31G level of theory. Theoretically we found four isomers of A-T basepair and the most stable isomer is one in which adenine and thymine are connected via two hydrogen bonding. The electronic properties were calculated by Time Dependent Density Functional Theory (TD-DFT) approach. \u0000Dhaka Univ. J. Sci. 67(1): 51-54, 2019 (January)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83036394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-30DOI: 10.3329/dujs.v67i1.54575
Mirajul Islam, N. Sultana, M. M. Hasan
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)
{"title":"Determinants of Postnatal Care Utilization for the Newborns in Urban Slums of Bangladesh: A Study Based on Bangladesh Urban Health Survey Data","authors":"Mirajul Islam, N. Sultana, M. M. Hasan","doi":"10.3329/dujs.v67i1.54575","DOIUrl":"https://doi.org/10.3329/dujs.v67i1.54575","url":null,"abstract":"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)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77888930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-30DOI: 10.3329/dujs.v67i1.54566
Meraj Alam, Md. Shafiqul Islam
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)
{"title":"Numerical Solutions of Time Dependent Partial Differential Equations Using Weighted Residual Method With Piecewise Polynomials","authors":"Meraj Alam, Md. Shafiqul Islam","doi":"10.3329/dujs.v67i1.54566","DOIUrl":"https://doi.org/10.3329/dujs.v67i1.54566","url":null,"abstract":"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. \u0000Dhaka Univ. J. Sci. 67(1): 5-12, 2019 (January)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"3597 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86671574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-30DOI: 10.3329/dujs.v67i1.54576
M. Matin, -. Mohammad Alauddin, T. Debnath, M. Islam, M. Aziz
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)
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