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Open Journal of Fluid Dynamics 2012年第4期2卷 120-129页

作者： md alamgir Kabir md abdullah al mahbub Department of Mathematics Comilla University Comilla Bangladesh Department of Natural Sciences Daffodil International University Dhaka Bangladesh

An analysis of Thermophoresis effect on unsteady magneto-hydrodynamic free convection flow over an inclined porous plate with time dependent suction in presence of magnetic field with heat generation has been considered by employing Nachtsheim-Swigert shooting iteration technique along with sixth order Runge-Kutta integration scheme. Resulting non-dimensional velocity, temperature and concentration profiles are then presented graphically for different values of the parameters entering into the problem. Finally, the effects of the pertinent parameters on the skin-friction coefficient, the rate of heat transfer (Nusselt number) and wall deposition flux (Stanton number), which are of physical interest, are exhibited in tabular form.

关键词： Heat Generation Magnetic Field Nusselt Number Stanton Number Thermophoresis

Soret-Dufour Effects on the MHD Flow and Heat Transfer of Microrotation Fluid over a Nonlinear Stretching Plate in the Presence of Suction

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Applied Mathematics 2013年第6期4卷 864-875页

作者： md abdullah al mahbub Nasrin Jahan Nasu Shomi Aktar Zillur Rahman Department of Accounting and Information System University of Chittagong Chittagong Bangladesh Department of Mathematics Comilla University Comilla Bangladesh

In this work, the Micropolar fluid flow and heat and mass transfer past a horizontal nonlinear stretching sheet through porous medium is studied including the Soret-Dufour effect in the presence of suction. A uniform magnetic field is applied transversely to the direction of the flow. The governing differential equations of the problem have been transformed into a system of non-dimensional differential equations which are solved numerically by Nachtsheim-Swigert iteration technique along with the sixth order Runge-Kutta integration scheme. The velocity, microrotation, temperature and concentration profiles are presented for different parameters. The present problem finds significant applications in hydromagnetic control of conducting polymeric sheets, magnetic materials processing, etc.

关键词： Heat Transfer Micropolar Fluid Porous Media Stretching Sheet Soret Number Dufour Number

Energy Harvesting in the Wake of An Inverted C-Shaped Bluff Body

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China Ocean Engineering 2024年第1期38卷 68-80页

作者： WANG Jun-lei LI Shen-fang md.mahbub alAM ZHU Hong-jun HU Guo-biao School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou 450000China Center for Turbulence Control Harbin Institute of Technology(Shenzhen)Shenzhen 518055China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China Internet of Things Thrust The Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511400China

This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff *** inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV *** hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental *** reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present *** is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH *** the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested *** the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or *** average drag coefficient becomes negative when L is 2D,3D,or *** carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH *** example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional ***,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D.

关键词： wake-induced vibration vortex-induced vibration galloping energy harvesting bluff body

Interaction of ciprofloxacin hydrochloride with sodium dodecyl sulfate in aqueous/electrolytes solution at different temperatures and compositions

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Chinese Journal of Chemical Engineering 2020年第1期28卷 216-223页

作者： Sk.md.ali Ahsan md.Ruhul Amin Shamim mahbub Mohammad Robel Molla Shahina Aktar Malik Abdul Rub md.Anamul Hoque Muhammad Nadeem Arshad Mohammed abdullah Khan Department of Chemistry Jahangirnagar UniversitySavarDhaka 1342Bangladesh Chemistry Department Faculty of ScienceKing Abdulaziz UniversityJeddah-21589Saudi Arabia Center of Excellence for Advanced Materials Research King Abdulaziz UniversityJeddah-21589Saudi Arabia

Interactions of ciprofloxacin hydrochloride(CPFH)with sodium dodecyl sulfate(SDS)were investigated by conductivity measurement in H2O/electrolyte solutions(NaCl,Na2SO4&Na3PO4)over 298.15–318.15 K temperature range(with 5 K interval)considering the human body *** all cases,two critical micelle concentrations(c*)were observed which are increased in the presence of drug and decreased in the presence of salts enunciating the presence of interaction amongst the studied ***(CPFH+SDS)system in the presence of salt,the c*values at 303.15 K and I=0.50 mmol·kg^-1 followed the order:CNaCl>CNa2SO4>***ΔG1,m0 andΔG2,m0values are found to be negative for all systems that show that the micellization process is thermodynamically ***(CPFH+SDS)system in water,theΔHm0&ΔSm0 values reveal that the micellization processes is both entropy dominated in almost all *** the occurrence of electrolytes,ΔHm0 andΔSm0 values indicate that micellization processes are both entropy&enthalpy restricted at upper temperature but it becomes totally entropy dependent at higher *** higher positiveΔSm0 values indicate the enhanced hydrophobic interaction in presence of *** enthalpy-entropy compensation was determined from the linear relationship betweenΔHm0 andΔSm0 values in every *** transfer energies as well as compensation temperature and intrinsic enthalpy were also evaluated and the behaviors were comparable to other biological system.

关键词： Ciprofloxacin hydrochloride Sodium dodecyl sulfate Critical micelle concentration Thermodynamic indices Hydrophobic effect

Design and analysis of high birefringence and nonlinearity with small confinement loss photonic crystal fiber

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Frontiers of Optoelectronics 2019年第2期12卷 165-173页

作者： Rekha SAHA md.mahbub HOSSAIN md. Ekhlasur RAHAMAN Himadri Shekhar MONDal Electronics and Communication Engineering Discipline Khulna UniversityKhulna 9208Bangladesh

High birefringence with low confinement loss photonic crystal fiber (PCF) has significant advantages in the field of sensing, dispersion compensation devices, nonlinear applications, and polarization filter. In this report, two different models of PCFs are presented and compared. Both the models contain five air holes rings with combination of circular and elliptical air holes arrangement. Moreover, the elliptical shaped air holes polarization and the third ring air holes rotational angle are varied. To examine different guiding characteristics, finite element method (FEM) with perfectly matched layer (PML) absorbing boundary condition is applied from 1.2 to 1.8 |im wavelength range. High birefringence, low confinement loss, high nonlinearity, and moderate disper-sion values are successfully achieved in both the PCFs models. Numeric analysis shows that model-1 gives higher birefringence (2.75 ×10^-2) and negative dispersion (-540.67 ps/(nm ·km)) at 1.55 |im wavelength. However, model-2 gives more small confinement loss than model-1 at the same wavelength. In addition, the proposed design demonstrates the variation of rotation angle has great impact to enhance guiding properties especially the birefringence.

关键词： birefringence dispersion polarization main-taining photonic crystal fiber (PCF) polarization-selective devices polarization

Rural-urban differences in distributions and determinants of facility delivery among women in Bangladesh

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Global Health Journal 2023年第4期7卷 222-229页

作者： Jannatun Nayeem Christina Stennett Atia Sharmeen md mahbub Hossain Gulam Muhammed al Kibria Comilla Medical College Comilla 3500Bangladesh University of Maryland School of Medicine BaltimoreMD 21201United States Morgan State University BaltimoreMD 21093United States Texas A&M School of Public Health College StationTexasTX 77843United States Johns Hopkins Bloomberg School of Public Health BaltimoreMD 21205United States

Introduction:The utilization of facility delivery is crucial to achieve sustainable development goals by reducing maternal and neonatal *** study aimed to compare the distributions and determinants of childbirth in health facilities in urban and rural regions of ***:Cross-sectional data from the 2017-2018 Bangladesh Demographic and Health Survey were *** logistic regression was ***:A total of 4751 women were included in the *** 50%of childbirths took place in health facilities,63.4%and 44.6%in urban and rural regions,***,the odds of the association between facility delivery and the studied factors were *** women had significantly lower odds of facility delivery in both rural(adjusted odds ratio[AOR]=0.3,95%confidence interval[CI]:0.2 to 0.5)and urban(AOR=0.2,95%CI:0.1 to 0.5)*** both regions,women with higher education levels,highly educated husbands,antenatal care(ANC),and higher wealth indexes had significantly higher odds of facility ***:Several common associated factors were ***,differences were observed regarding distributions of these *** differences in facility delivery utilization could result from lower ANC utilization,socioeconomic status,and transportation facilities in rural regions than urban regions;therefore,improving these conditions could increase facility delivery in these regions.

关键词： Bangladesh Facilitydelivery Determinants Distributions Urban Rural Childbirth

Structural, Dielectric, and Magnetic Properties of Ba-Doped Multiferroic Bismuth Ferrite

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Acta Metallurgica Sinica(English Letters) 2015年第8期28卷 958-964页

作者： Rubayyat mahbub Takian Fakhrul.md Fakhrul Islam Mehedi Hasan Arman Hussain M.A.Matin M.A.Hakim Department of Glass and Ceramic Engineering Bangladesh University of Engineering and Technology Department of Materials and Metallurgical Engineering Bangladesh University of Engineering and Technology

The main focus of the research was to correlate the microstructure with dielectric and magnetic properties of Bi1-xBaxFeO3 samples. Bi1-xBaxFeO3 samples（x = 0.1, 0.2 and 0.3） were synthesized by the conventional solid-state reaction method using nano-powders of Bi2O3, Fe2O3, and BaCO3. Thereafter, field emission scanning electron microscope and X-ray diffraction（XRD） techniques were used to examine the structure and phase of the samples. Phase analysis by XRD indicated that the single-phase perovskite structure was formed with possible increment in lattice parameter with increasing Ba doping. Complex permeability（u＇iand u＇＇i） measured using impedance analyzer confirmed the increase in magnetic property with increasing Ba doping. Finally, dielectric constant（k） was analyzed as a function of temperature at different frequencies. Dielectric constant as high as 2900 was attained in this research for Bi0.8Ba0.2FeO3 sample due to reduction in leakage current at this composition.

关键词： Multiferroic Bismuth ferrite Dielectric Complex permeability

Predicting Rainfall Using the Principles of Fuzzy Set Theory and Reliability Analysis

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American Journal of Computational Mathematics 2013年第4期3卷 337-348页

作者： mahbub Hasan Salam md. mahbubush Khan Chandrasekhar Putcha Ashraf al-Hamdan Chance M. Glenn College of Engineering Technology and Physical Sciences Alabama Agricultural and Mechanical University Normal USA Department of Civil & Environmental Engineering University of Alabama Huntsville USA Department of Civil and Environmental Engineering California State University Fullerton USA Department of Civil Engineering Alabama Agricultural and Mechanical University Normal USA Department of Mathematics Alabama Agricultural and Mechanical University Normal USA

The paper presents occurrence of rainfall using principles of fuzzy set theory and principles of reliability analysis. Both the abstract and the rest of the paper are discussed from these two points of view. First, a fuzzy inference model for predicting rainfall using scan data from the USDA Soil Climate Analysis Network Station at alabama Agricultural and Mechanical University (AAMU) campus for the year 2004 is presented. The model further reflects how an expert would perceive weather conditions and apply this knowledge before inferring a rainfall. Fuzzy variables were selected based on judging patterns in individual monthly graphs for 2003 and 2004 and the influence of different variables that caused rainfall. A decrease in temperature (TP) and an increase in wind speed (WS) when compared between the ith and (i ? 1)th day were found to have a positive relation with a rainfall (RF) occurrence in most cases. Therefore, TP and WS were used in the antecedent part of the production rules to predict rainfall (RF). Results of the model showed better performance when threshold values for 1) Relative Humidity (RH) of ith day;2) Humidity Increase (HI) between the ith and (i ? 1)th day;and 3) Product (P) of decrease in temperature (TP) and an increase in wind speed (WS) were introduced. The percentage of error was 12.35 when compared the calculated amount of rainfall with actual amount of rainfall. This is followed by prediction of rainfall using principles of reliability analysis. This is done by comparing theoretical probabilities with experimental probabilities for the occurrence of two main events, namely, Relative Humidity (RH) and Humidity Increase (HI) being in between specified threshold values. The experimental values of probability are falling in between μ ? σ and μ + σ for both RH and HI parameters, where μ is the mean value and σ is the standard deviation.

关键词： Fuzzy Sets Prediction Reliability Rainfall Water Resources

Flow-Induced Vibration of a Cantilevered Cylinder in the Wake of a Fixed Cylinder

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Flow-Induced Vibration of a Cantilevered Cylinder in the Wak...

Groundwater Depletion with Expansion of Irrigation in Barind Tract: A Case Study of Tanore Upazila

第十二届全国流体力学学术会议

作者： md.mahbub alam Chen Guanghao Center of Turbulence Control Harbin Institute of Technology (Shenzhen)

This work presents an experimental study of the flow-induced vibration of a cantilevered circular cylinder in the wake of another fixed cylinder for the diameter ratio d/D = 0.24 – 1.0 and spacing ratio L/d = 1.0 – 5.5 under the reduced velocity U = 3.8 – 68.3, where d and D are diameters of the upstream and downstream cylinders, respectively, and L is the spacing from the upstream cylinder center to the front stagnation point of the downstream cylinder. Measurements are done for the vibration response, vortex shedding frequency, surface pressure distribution, and flow structures via laser vibrometer, hotwire anemometer, pressure scanner, and particle-image-velocimetry(PIV) system, respectively. A smaller d/D and/or L/d is more prone to causing galloping generation and hysteresis in the galloping response. The galloping vibration involves alternate reattachment and switch of the gap shear layers. The switch of the gap shear layers leads to reduced added mass and added damping, hence exciting and sustaining the vibrations. The initiation of galloping generation wades through pre-initial, initial, and late transitions before reaching steady vibration, where the work done by fluid flow is larger than the dissipation. In addition, this study presents(ⅰ) the roles of effective added mass and effective added damping in vibration initiation and sustainability,(ⅱ) wake structure evolutions in the streamwise and spanwise directions, and(ⅲ) detailed fluid-structure interactions involved.

关键词： flow-induced vibration cantilever cylinder gap shear layer galloping

来源： cnki会议评论

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Journal of Water Resource and Protection 2012年第8期4卷 567-575页

作者： md. Marufur Rahman A. Q. M. mahbub University of Dhaka

In this paper successive depletion of groundwater level with expansion of groundwater irrigation in Barind Tract has been discussed from mid 1960s to 2010 in the context of Tanore Upazila, which is located in severely drought prone area of northwest Bangladesh. After starting of groundwater irrigation in Bangladesh, it spread rapidly all over the country, and about 80% of agricultural land is now supplied irrigation from groundwater. Availability of irrigation in Barind Tract has revolutionized its agriculture, but groundwater level is successively falling all over the country due to excessive withdrawal, and this process is accelerating due to water withdrawal from major rivers by upstream countries. In northwestern part of Bangladesh groundwater depletion problem is severe because this part is free from seasonal flooding. Only source of recharging of groundwater aquifer in this area is rainfall, but rainfall is also lowest here among the country. In this context, this paper presents the change of groundwater level with the spreading of groundwater irrigation in Barind Tract. Hydrograph analysis, groundwater level mapping, groundwater depletion rate calculation are done from groundwater level observation well data of Bangladesh Water Development Board (BWDB) and Barind Multipurpose Development Authority (BmdA). Climatic condition is analyzed by calculation of rainfall deviation from the data of Bangladesh Meteorological Department (Bmd). Focus Group Discussion (FGD) and interviews with farmers and experts of different branches are conducted to understand the nature of problems in the study area. Agricultural pattern, cropping intensity (262% in study area and national intensity is 180%), methods of cultivation, crop variety and yields all show a positive change after starting of groundwater irrigation in mid 1980s, but water level is continuously lowering at the rate of 1.37 ft/y in wet season and 0.72 ft/y in dry season. Water is the main input for agriculture but

关键词： Groundwater Depletion Irrigation Barind Tract Tanore