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Induced Hyperfine Field in Doped Chalcopyrite Compounds Cu(In1-xAx)S2 (A = V and Cr) 铜(In1-xAx)S2 (A = V和Cr)掺杂黄铜矿化合物的诱导超细场
Dhaka University Journal of Science Pub Date : 2022-07-04 DOI: 10.3329/dujs.v69i3.60024
M. Shahjahan, Raisul Islam
{"title":"Induced Hyperfine Field in Doped Chalcopyrite Compounds Cu(In1-xAx)S2 (A = V and Cr)","authors":"M. Shahjahan, Raisul Islam","doi":"10.3329/dujs.v69i3.60024","DOIUrl":"https://doi.org/10.3329/dujs.v69i3.60024","url":null,"abstract":"Hyperfine field and electronic states of doped chalcopyrite compounds Cu(In1-xAx)S2 with A = V and Cr are calculated by Korringa- Kohn-Rostoker Green’s function method, where x denotes the concentration of A atoms. The V and Cr doped compounds are ferromagnetically stable in terms of energy minimization and their electronic states are half metallic. The hyperfine fields in the stable ferromagnetic (FM) state are calculated with their valence and core contributions. In addition, site preference local magnetic moments are calculated for the FM and disordered spin moment (DSM) states. Density of states (DOS) exhibit the spintronic property of half metallicity. The local core and valence field polarizations are found in the doped chalcopyrite systems, where the s-orbital hybridization with the local d-shell is explained in terms of some exchange mechanisms.\u0000Dhaka Univ. J. Sci. 69(3): 149-153, 2022 (June)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78166636","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}
引用次数: 0
Electrochemical Studies on Interactions of Cu2+, Zn2+ and Cd2+ with Leucine and Isoleucine Cu2+、Zn2+和Cd2+与亮氨酸和异亮氨酸相互作用的电化学研究
Dhaka University Journal of Science Pub Date : 2022-07-04 DOI: 10.3329/dujs.v69i3.60035
M. Hasan, M. Ehsan
{"title":"Electrochemical Studies on Interactions of Cu2+, Zn2+ and Cd2+ with Leucine and Isoleucine","authors":"M. Hasan, M. Ehsan","doi":"10.3329/dujs.v69i3.60035","DOIUrl":"https://doi.org/10.3329/dujs.v69i3.60035","url":null,"abstract":"The interaction of some divalent metal ions with leucine (leu) and isoleucine (ile) was studied in aqueous solution. Electrochemical techniques like cyclic voltammetry, chronoamperometry and chronocoulometry were used for this study. The electrochemical study demonstrates that the maximum interaction of each metal ion occurs with two deprotonated ligand. The metal ions exchange electrons quasi-reversibly in presence of the ligands and some sort of chemical reaction may be competing with diffusion process at the electrode surface. The current-time and charge-time response accounts for the adsorption of reactant or product or both at the electrode surface.\u0000Dhaka Univ. J. Sci. 69(3): 230-237, 2022 (June)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"134 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74762504","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}
引用次数: 0
Numerical Method for 2D Quasi-linear Hyperbolic Equation on an Irrational Domain: Application to Telegraphic Equation 二维拟线性双曲型方程在无理区上的数值解法:在电报方程中的应用
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56492
Bishnu Pada Ghosh, N. C. Roy
{"title":"Numerical Method for 2D Quasi-linear Hyperbolic Equation on an Irrational Domain: Application to Telegraphic Equation","authors":"Bishnu Pada Ghosh, N. C. Roy","doi":"10.3329/dujs.v69i2.56492","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56492","url":null,"abstract":"We develop a novel three-level compact method (implicit) of second order in time and space directions using unequal grid for the numerical solution of 2D quasi-linear hyperbolic partial differential equations on an irrational domain. The stability analysis of the model problem for unequal mesh is discussed and it is revealed that the developed scheme is unconditionally stable for the Telegraphic equation. For linear difference equations on an irrational domain, the alternating direction implicit method is discussed. The projected technique is scrutinized on several physical problems on an irrational domain to exhibitthe accuracy and effectiveness of the suggested method.\u0000Dhaka Univ. J. Sci. 69(2): 116-123, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76426405","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}
引用次数: 1
Facial Expression Identification using Regularized Supervised Distance Preserving Projection 基于正则化监督距离保持投影的面部表情识别
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56485
S. Jahan, Moriyam Akter, Sifta Yeasmin, Farhana Ahmed Simi
{"title":"Facial Expression Identification using Regularized Supervised Distance Preserving Projection","authors":"S. Jahan, Moriyam Akter, Sifta Yeasmin, Farhana Ahmed Simi","doi":"10.3329/dujs.v69i2.56485","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56485","url":null,"abstract":"Facial expression recognition is one of the most reliable and a key technology of advanced human-computer interaction with the rapid development of computer vision and artificial intelligence. Nowadays, there has been a growing interest in improving expression recognition techniques. In most of the cases, automatic recognition system’s efficiency depends on the represented facial expression feature. Even the best classifier may fail to achieve a good recognition rate if inadequate features are provided. Therefore, feature extraction is a crucial step of the facial expression recognition process. In this paper, we have used Regularized Supervised Distance Preserving Projection for extracting the best features of the images. Numerical experiment shows that the use of this technique outperforms many of state of art approaches in terms of recognition rate.\u0000Dhaka Univ. J. Sci. 69(2): 70-75, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"18 12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82890199","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}
引用次数: 0
Synthesis and Characterization of Mixed Ligand Complexes of Copper(II) with Adenine and Dicarboxylic Acids 铜(II)与腺嘌呤和二羧酸混合配体配合物的合成与表征
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56486
Sumaia Abdullah, M. Rahman, Humaira Yeasmin, A. Shaikh, P. K. Bakshi
{"title":"Synthesis and Characterization of Mixed Ligand Complexes of Copper(II) with Adenine and Dicarboxylic Acids","authors":"Sumaia Abdullah, M. Rahman, Humaira Yeasmin, A. Shaikh, P. K. Bakshi","doi":"10.3329/dujs.v69i2.56486","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56486","url":null,"abstract":"Three mixed ligand complexes of copper(II) with adenine and dicarboxylic acids have been synthesized. The resulting complexes were characterized by their melting point, solubility, metal content analysis, FT-IR and UV-visible spectroscopy, magnetic measurement, thermal analysis, cyclic voltammetric measurement and X-ray powder diffraction study. The products are microcrystalline powder, slightly soluble in water and decompose at high temperature. Under experimental condition, the ligands adenine (Ade) behaves as a neutral ligand, whereas oxalic acid (OxH2), succinic acid (SucH2) and tartaric acid (TarH2) are doubly deprotonated to form dianionic ligands that are coordinated to the Cu(II) ion. The Cu(II) content analysis of the complexes confine to their stoichiometry [Cu(Ade)(L)(H2O)] (L = Ox, Suc, or Tar dianion). Electrochemical redox behavior of the complexes in their reaction medium was also examined. They exhibit quasi-reversible one-electron transfer processes.\u0000Dhaka Univ. J. Sci. 69(2): 76-81, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"89 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80248247","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}
引用次数: 1
Pregnancy Complications in Women with PCOS: A Meta-Analysis 多囊卵巢综合征妇女妊娠并发症:一项荟萃分析
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56487
K. Tanvir, Mohammad Lutfor Rahman
{"title":"Pregnancy Complications in Women with PCOS: A Meta-Analysis","authors":"K. Tanvir, Mohammad Lutfor Rahman","doi":"10.3329/dujs.v69i2.56487","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56487","url":null,"abstract":"Polycystic ovary syndrome (PCOS) is a hormonal disorder which affects women in their reproductive ages. There might have association between maternal and neonatal complications with PCOS. The goal of this study is to look for the association between polycystic ovary syndromes (PCOS) and obstetric complications through meta-analysis on the basis of previously published studies from 2000 to 2019. In the current endeavour 17 studies involving 1975 women with PCOS and 10812 controls were selected for pooling. During pregnancy period women who have PCOS showed a significantly higher risk of developing gestational diabetes mellitus (GDM) (RR 2.51; 95% CI: 1.71-3.65), pregnancy induced hypertension (PIH) (RR 2.76; 95% CI: 2.04-3.72), preeclampsia (RR 2.14; 95% CI: 1.34-3.40), preterm birth (RR 1.41; 95% CI: 1.08-1.85) compared to controls. Neonatal birth weight is significantly lower (SMD -0.18; 95% CI: -0.33 to -0.03) compared to controls. It is concluded that women who have PCOS have greater chance of having pregnancy complications as well as risk of neonatal complications such as having low birth weight.\u0000Dhaka Univ. J. Sci. 69(2): 82-87, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"71 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73779078","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}
引用次数: 0
Studying the Third Cumulant of the Mixture of Dirichlet-multinomial Distributions dirichlet -多项式混合分布的第三次累积量研究
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56489
Farzana Afroz
{"title":"Studying the Third Cumulant of the Mixture of Dirichlet-multinomial Distributions","authors":"Farzana Afroz","doi":"10.3329/dujs.v69i2.56489","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56489","url":null,"abstract":"Traditionally, the overdispersion parameter ϕ is estimated by using Pearson’s lack of fit statistic X2or the Deviance statistic D, which do not perform well in the case of sparse data. This paper particularly focuses on an estimator ϕnew of overdispersion parameter which was proposed for sparse multinomial data. The estimator was derived on the basis of an assumption on the 3rd cumulant of the response variable.When the data comes from the Dirichlet-multinomial distribution ϕnew is known to have the lowest root mean squared error comparing to the other three estimators. In this paper the 1st to 3rd order raw moments of the finite mixture of Dirichlet-multinomial distributions are derived, which results in complicated mathematical expressions. Furthermore, it is found that the 3rd cumulant of this mixture does not satisfy the assumption which is considered in the derivation of ϕnew .\u0000Dhaka Univ. J. Sci. 69(2): 96-100, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80991199","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}
引用次数: 0
Performance Enhancement of an a-Si:H/μc-Si:H Heterojunction p-i-n Solar Cell by Tuning the Device Parameters a-Si:H/μc-Si:H异质结p-i-n太阳能电池性能的优化研究
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56488
Md Nazmul Islam, H. R. Ghosh
{"title":"Performance Enhancement of an a-Si:H/μc-Si:H Heterojunction p-i-n Solar Cell by Tuning the Device Parameters","authors":"Md Nazmul Islam, H. R. Ghosh","doi":"10.3329/dujs.v69i2.56488","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56488","url":null,"abstract":"In this work, the solar cell design parameters like- layer thickness, bandgap, donor and acceptor concentrations are varied to find optimum structure of a hydrogenated amorphous silicon (a-Si:H) and hydrogenated microcrystalline silicon (μc-Si:H) heterojunction p-i-n solar cell. A thin a-Si:H p-layer of 1 to 5 nm followed by a thick a-Si:H i-layer of thickness 1400 to 1600 nm and then thin n-layer of thickness 1 to 5 nm with acceptor concentration of 102 cm−3 and donor concentration of 1020 cm−3 and the bandgaps of p-, i-, and n- layers with higher bandgaps closer to 2.2 eV for a-Si:H p-layer, 1.85 eV for a-Si:H i-layer, and 1.2 eV for μc-Si:H n-layer have showed better performances. The optimum cell has a JSC of 18.93 mA/cm2, VOC of 1095 mV, Fill factor of 0.7124, and efficiency of 14.77%. The overall external quantum efficiency of the numerically designed cell also remained very high from 85-95 % for wavelengths of 300-650 nm range. This indicates that the device will perform its best under both high and low frequency i.e. ultra-violet, near visible and visible light wavelengths.\u0000Dhaka Univ. J. Sci. 69(2): 88-95, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85052843","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}
引用次数: 0
Analyzing Infant Mortality in Rural Bangladesh: A Frailty Modeling Approach 分析孟加拉国农村婴儿死亡率:脆弱性建模方法
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56484
B. Pal, Ahsan Rahman Jaamee
{"title":"Analyzing Infant Mortality in Rural Bangladesh: A Frailty Modeling Approach","authors":"B. Pal, Ahsan Rahman Jaamee","doi":"10.3329/dujs.v69i2.56484","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56484","url":null,"abstract":"In practice, it may happen that data may arise from a hierarchical structure i.e., a cluster is nested within another cluster. In this case, nested frailty model is appropriate to analyze survival data to obtain optimal estimates of the parameters of interest. To identify significant determinants of infant mortality in rural Bangladesh, survival data have been extracted from Bangladesh Demographic and Health Survey (BDHS), 2014. Because of the presence of two-level clustering in data, nested frailty model has been employed for the purpose of analysis. Recommendations have been suggested based on the results obtained from the survival model to reduce the infant mortality in rural Bangladesh to a great extent.\u0000Dhaka Univ. J. Sci. 69(2): 63-69, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79079346","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}
引用次数: 1
Track and Landfall Characteristics of Very Severe Cyclonic Storm Fani over the Bay of Bengal using WRF Model 利用WRF模式分析孟加拉湾甚强气旋风暴范尼的路径和登陆特征
Dhaka University Journal of Science Pub Date : 2021-12-01 DOI: 10.3329/dujs.v69i2.56490
Md Shakil Hossain, Md Abdus Samad, Most Razia Sultana, M. Mallik, Md Joshem Uddin
{"title":"Track and Landfall Characteristics of Very Severe Cyclonic Storm Fani over the Bay of Bengal using WRF Model","authors":"Md Shakil Hossain, Md Abdus Samad, Most Razia Sultana, M. Mallik, Md Joshem Uddin","doi":"10.3329/dujs.v69i2.56490","DOIUrl":"https://doi.org/10.3329/dujs.v69i2.56490","url":null,"abstract":"An attempt has been made to assess the capability of the Weather Research and Forecasting (WRF) model in simulating the track and landfall characteristics of Tropical Cyclone (TC) Fani (25th April – 05th May 2019) over the Bay of Bengal (BoB). WRF model has conducted on a single domain of 10 km horizontal resolution using Global Data Assimilation System (GDAS) data (0.250×0.250). The model predicted outcomes show auspicious agreement with the observed datasets of the Bangladesh Meteorological Department (BMD) and India Meteorological Department (IMD). It is found that the diminished lead time of the model run plays a crucial role in delivering good consistency with the minimum forecast uncertainty. A strong correlation between the track and intensity forecast deviations has also been determined. According to the results, the model simulation which captures the minimum deviation in the intensity forecast also ensures better track prediction of the system. The feasibility of the track and landfall forecast by the model even up to 27 hr advance is reasonably well. Finally, it can be decided that the model is capable to predict the cyclonic storm Fani precisely and it can be chosen confidently for future events over the BoB.\u0000Dhaka Univ. J. Sci. 69(2): 101-108, 2021 (July)","PeriodicalId":11280,"journal":{"name":"Dhaka University Journal of Science","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82581026","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}
引用次数: 4
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