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Effect of controlled rolling on the martensitic hardenability of dual phase steel

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International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 165-169页

作者： mohammad Ajmal Masood ahmed Tindyala Ron Priestner Department of Metallurgical & Materials Engineering University of Engineering & TechnologyG.T. Road Lahore-54890Pakistan Manchester Materials Science Center University of Manchester Institute of Science and Technology (UMIST)ManchesterM1 7HSUK

The C-Mn and C-Mn-Nb steels were thermo-mechanically processed to develop dual phase steel and to study the effect of controlled rolling on the martensitic hardenability of austenite. The steel specimens were intercritically annealed at 790℃, rolled at that temperature to the reductions of 10%, 23%, and 47% and immediately cooled at different rates. Quantitative metallography was used to construct the microstructure map, which illustrated that increasing deformation progressively reduced the proportion of new ferrite formed at all cooling rates and increased the amount of martensite at fast and intermediate rates. The martensitic hardenability of austenite remaining after all the rolling reductions was plotted as a function of cooling rates. It was observed that for the austenite-martensite conversion efficiencies greater than about 25%, controlled rolling increased the martensitic hardenability of austenite.

关键词： controlled rolling dual phase steel intercritical annealing hardenability phase transformation

Seismic design factors for RC special moment resisting frames in Dubai,UAE

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Earthquake Engineering and Engineering Vibration 2011年第4期10卷 495-506页

作者： mohammad AlHamaydeh Sulayman Abdullah ahmed Hamid Abdilwahhab Mustapha Department of Civil Engineering American University of Sharjah

This study investigates the seismic design factors for three reinforced concrete （RC） framed buildings with 4, 16 and 32-stories in Dubai, UAE utilizing nonlinear analysis. The buildings are designed according to the response spectrum procedure defined in the 2009 International Building Code （IBC＇09）. Two ensembles of ground motion records with 10% and 2% probability of exceedance in 50 years （10/50 and 2/50, respectively） are used. The nonlinear dynamic resPonses to the earthquake records are computed using IDARC-2D. Key seismic design parameters are evaluated; namely, response modification factor （R）, deflection amplification factor （Cd）, system overstrength factor （Ωo）, and response modification factor for ductility （Rd） in addition to inelastic interstory drift. The evaluated seismic design factors are found to significantly depend on the considered ground motion （10/50 versus 2/50）. Consequently, resolution to the controversy of Dubai seismicity is urged. The seismic design factors for the 2/50 records show an increase over their counterparts for the 10/50 records in the range of 200%-400%, except for the D~ factor, which shows a mere 30% increase. Based on the observed trends, perioddependent R and Cd factors are recommended if consistent collapse probability （or collapse prevention performance） in moment frames with varying heights is to be expected.

关键词： Seismic design factors reinforced concrete special moment resisting frame Dubai UAE

Sources and Ecological Risks of Heavy Metals in Soils Under Different Land Uses in Bangladesh

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Pedosphere 2019年第5期29卷 665-675页

作者： mohammad Saiful ISLAM mohammad Kawser ahmed mohammad Habibullah AL-MAMUN Shah mohammad Asraful ISLAM Department of Soil Science Patuakhali Science and Technology UniversityDumkiPatuakhali 8602 (Bangladesh) Environment and Information Sciences Yokohama National UniversityYokohama 240-8501 (Japan) Department of Oceanography University of DhakaDhaka 1000 (Bangladesh) Department of Fisheries University of DhakaDhaka 1000 (Bangladesh) Department of Plant Pathology Patuakhali Science and Technology UniversityDumkiPatuakhali 8602 (Bangladesh)

Soil heavy metal pollution, influenced by both natural and anthropogenic factors, significantly reduces environmental quality. In this study, Cr, Ni, Cu, As, Cd, and Pb in eight different land-use soils from Patuakhali District in Bangladesh were assessed. Concentrations of Cr, Ni, Cu, As, Cd, and Pb in soils were 1-87, 5-271, 4-181, 0-80, 0.2-24.0, and 5-276 mg kg-1, respectively, measured using an inductively coupled plasma-mass spectrometer. The enrichment factor, pollution load index (PLI), and contamination factor (CJ) of metal i were used to assess the ecological risk posed by metals in soils. The PLI ranged from 0.78 to 2.66, indicating baseline levels to progressive deterioration of soil due to metal contamination. However, C;of Cd ranged from 1.8 to 12.0, which showed that the studied soils were strongly impacted by Cd. Considering the severity of the potential ecological risk of a single metal, the descending order was Cd > As > Pb > Cu > Ni > Cr. Soils under all land uses showed moderate to very high potential ecological risk.

关键词： Cd contamination factor degree of contamination enrichment factor environmental quality pollution load index soil deterioration soil pollution

Nature-inspired Hybrid Optimization Algorithms for Load Flow Analysis of Islanded Microgrids

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Journal of Modern Power Systems and Clean Energy 2020年第6期8卷 1250-1258页

作者： Saad mohammad Abdullah Ashik ahmed Quazi Nafees Ul Islam the Department of Electrical and Electronic Engineering Islamic University of TechnologyBoard BazarGazipur 1704Bangladesh

Load flow analysis is a significant tool for proper planning,operation,and dynamic analysis of a power system that provides the steady-state values of voltage magnitudes and angles at the fundamental ***,due to the absence of a slack bus in an islanded microgrid,modified load flow algorithms should be adopted considering the system frequency as one of the solution *** paper proposes the application of nature-inspired hybrid optimization algorithms for solving the load flow problem of islanded *** nature-inspired algorithms such as genetic algorithm(GA),differential evolution(DE),flower pollination algorithm(FPA),and grasshopper optimization algorithm(GOA)are separately merged with imperialistic competitive algorithm(ICA)to form four hybrid algorithms named as ICGA,ICDE,ICFPA,and *** of these algorithms are tested on the 6-bus test system and the modified IEEE 37-bus test system.A comparison among the proposed algorithms is carried out in terms of statistical analysis conducted using SPSS statistics *** the statistical analysis,it is identified that on an average,ICDE takes less number of iterations and consequently needs less execution time compared with other algorithms in solving the load flow problem of islanded microgrids.

关键词： Nature-inspired hybrid algorithm global optimization islanded microgrid load flow analysis

Rate of elapsed polymerization of hydroxyethylacrylate gel induced by gamma irradiation

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Nuclear Science and Techniques 2008年第4期19卷 218-222页

作者： Khalid ahmed RABAEH Elias SAION mohammad ahmed Ali OMER Azhar Abdul RAHMAN mohammad Yusif HUSSAIN Shahrim ISKANDAR Noria mohammad ALI Department of Physics Universiti Putra Malaysia 43400 UPM SerdangSelangorMalaysia Nuclear Agency of Malaysia

The rate of elapsed polymerization of polyhydroxyethylacrylate in gelatin has been studied to investigate the effect of co-monomers consumption at a given dose. The polymer gel dosimeters consisted of 2%～4% N,N-methyelene-bis-acrylamide cross-linker,2%～4% 2-hydroxyethylacrylate monomer and gelatin at 3% and 5%. The dosimeters were irradiated by using 60Co teletherapy γ-ray source up to 20 Gy at a constant dose rate. The relaxation rate of water proton in the dosimeters at different doses and co-monomer concentrations were measured using a nuclear magnetic resonance spectroscopy. The rate of elapsed polymerization decreases with increasing the dose and the initial concentration of co-monomers. The rate of consumption of co-monomers increases with an increase of the polymerization and the gelatin content of the polymer gel.

关键词：高聚物缓和速度剂量器射线

Assaying the allelopathic effects of Eucalyptus camaldulensis in a nursery bed incorporated with leaf litter

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Journal of Forestry Research 2018年第3期29卷 592-598页

作者： Romel ahmed mohammad Shafioul Alam Farid Uddin ahmed M.K.Hossain Department of Forestry and Environmental Science Shahjalal University of Science and TechnologySylhet 3114Bangladesh Ministry of Public Administration TeknafCoxsbazarDhaka 4761Bangladesh Arannayk Foundation House 21 Western RoadDOHSBananiDhaka 1206Bangladesh Institute of Forestry and Environmental Science University of ChittagongChittagong 4331Bangladesh

Allelopathic effects of Eucalyptus camaldulensis Dehnh. were confirmed in Petri dish and pot experiments in our previous studies. However, the degree to which such effects under controlled experiments exist in more complex ecological settings remains to be tested. Thus, the present study was carried out by incorporating different proportions of ground litter of E. camaldulensis in soil. The growth of three agricultural crops: falen(Vigna unguiculata(L.) Walp.), chickpea(Cicer arietinum L.), and arhor(Cajanus cajan(L.) Millsp.), and two tree species, kala koroi(Albizia procera(Roxb.) Benth.) and ipil ipil(Leucaena leucocephala(Lam.) de Wit) were tested. There were inhibitory effects of leaf litter on germination, shoot and root growth, leaf number, and collar diameter as well as a reduction of nodulation by legume crops(25–80%reduction). The extent of the effects was dependent on the proportion of leaf litter, the species and the type of traits. In contrast to shoot growth, the effect on root growth was more severe. No effect on germination was found with the agriculture crops while the two tree species showed reduced germination. The effect was greater in the presence of higher proportions of leaf litter mixed in soil while in some cases lower proportions stimulated growth. Not all species were suppressed; A. procera, C. cajan, V. unguiculata showed compatible growth while C. arietinum and *** were found incompatible. This study provides evidence that E. camaldulensis has allelopathic potential under field conditions and a careful selection of associated crops in agroforestry systems is highly recommended.

关键词： Allelopathy Eucalyptus camaldulensis Inhibitory effects Germination Growth Nodulation

Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

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Frontiers of Structural and Civil Engineering 2021年第6期15卷 1400-1414页

作者： Tarek Uddin MOHAMMED Aziz Hasan MAHMOOD mohammad Zunaied-Bin-HARUN Jamil ahmed JOY MdAsif ahmed Department of Civil and Environmental Engineering Islamic University of Technology(IUT)Organization of Islamic Cooperation(OIC)Board BazarGazipur 1704Bangladesh Centre for Infrastructure Engineering and Safety School of Civil and Environmental EngineeringThe University of New South WalesSydneyNSW 2052Australia Department of Civil Engineering European University of BangladeshMirpurDhaka 1216Bangladesh

Aggregates are the biggest contributor to concrete volume and are a crucial parameter in dictating its mechanical *** such,a detailed experimental investigation was carried out to evaluate the effect of sand-toaggregate volume ratio(s/a)on the mechanical properties of concrete utilizing both destructive and non-destructive testing(employing UPV(ultrasonic pulse velocity)measurements).For investigation,standard cylindrical concrete samples were made with different s/a(0.36,0.40,0.44,0.48,0.52,and 0.56),cement content(340 and 450 kg/m^(3)),water-to-cement ratio(0.45 and 0.50),and maximum aggregate size(12 and 19 mm).The effect of these design parameters on the 7,14,and 28 d compressive strength,tensile strength,elastic modulus,and UPV of concrete were *** careful analysis demonstrates that aggregate proportions and size need to be optimized for formulating mix designs;optimum ratios of s/a were found to be 0.40 and 0.44 for the maximum aggregate size of 12 and 19 mm,respectively,irrespective of the W/C(water-to-cement)and cement content.

关键词： aggregates non-destructive testing sand-to-aggregate volume ratio(s/a) maximum aggregate size(MAS)

The Two-Dimensional Supersonic Flow and Mixing with a Perpendicular Injection in a Scramjet Combustor

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Journal of Thermal Science 2003年第4期12卷 371-380页

作者： mohammad Ali S. ahmed A.K.M. Sadrul Islam Department of Mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh.Department of Mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh.Department of Mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh.

A numerical investigation has been performed on supersonic mixing of hydrogen with air in a Scramjet (Supersonic Combustion Ramjet) combustor and its flame holding capability by solving Two-Dimensional full Navier-Stokes equations. The main flow is air entering through a finite width of inlet and gaseous hydrogen is injected perpendicularly from the side wall. An explicit Harten-Yee Non-MUSCL Modified-flux-type TVD scheme has been used to solve the system of equations, and a zero-equation algebraic turbulence model to calculate the eddy viscosity coefficient. In this study the enhancement of mixing and good flame holding capability of a supersonic combustor have been investigated by varying the distance of injector position from left boundary keeping constant the backward-facing step height and other calculation parameters. The results show that the configuration for small distance of injector position has high mixing efficiency but the upstream recirculation can not evolved properly which is an important factor for flame holding capability. On the other hand, the configuration for very long distance has lower mixing efficiency due to lower gradient of hydrogen mass concentration on the top of injector caused by the expansion of side jet in both upstream and downstream of injector. For moderate distance of injector position, large and elongated upstream recirculation can evolve which might be activated as a good flame holder.

关键词： scramjet engine TVD scheme finite width of inlet supersonic mixing parallel air stream flame holding.

Modified particle swarm optimization for optimum design of spread footing and retaining wall

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第6期12卷 415-427页

作者： mohammad KHAJEHZADEH Mohd Raihan TAHA ahmed EL-SHAFIE Mahdiyeh ESLAMI Department of Civil Engineering Anar BranchIslamic Azad University Department of Civil and Structural Engineering University Kebangsaan Malaysia Department of Electrical Engineering Anar BranchIslamic Azad University

This paper deals with the economically optimized design and sensitivity of two of the most widely used systems in geotechnical engineering: spread footing and retaining wall. Several recent advanced optimization methods have been developed, but very few of these methods have been applied to geotechnical problems. The current research develops a modified particle swarm optimization (MPSO) approach to obtain the optimum design of spread footing and retaining wall. The algorithm handles the problem-specific constraints using a penalty function approach. The optimization procedure controls all geotechnical and structural design constraints while reducing the overall cost of the structures. To verify the effectiveness and robustness of the proposed algorithm, three case studies of spread footing and retaining wall are illustrated. Comparison of the results of the present method, standard PSO, and other selected methods employed in previous studies shows the reliability and accuracy of the algorithm. Moreover, the parametric performance is investigated in order to examine the effect of relevant variables on the optimum design of the footing and the retaining structure utilizing the proposed method.

关键词： Particle swarm optimization (PSO) Spread footing Retaining wall Sensitivity analysis