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Journal of Advanced Dielectrics 2019年第2期9卷 63-71页

作者： mohammad Sajjad Hossain Yeasmin Akter mohammad Shahjahan Muhammad Shahriar Bashar MostHosney Ara Begum MdMoazzem Hossain Suravi islam Nazia Khatun MdAl-Mamun Industrial Physics Division BCSIR Laboratories Dhaka BCSIRDhaka-1205Bangladesh Department of Physics University of Chittagong Chottogram-4331Bangladesh Institute of Fuel Research and Development BCSIR Dhaka-1205Bangladesh Bangladesh Atomic Energy Centre BAEC Dhaka-1000Bangladesh

Polycrystalline NiCuZn ferrite(Ni_(x)Cu_(0.3)Zn(0.7-x)Fe_(2)O_(4);x=0.2,0.3,0.4 and 0.5)were prepared through solgel auto combustion method applying double sintering ***,morphological,elemental analyses(EDS),Fourier-transform infrared spectroscopy(FTIR),Direct Current(DC)electrical resistivity,dielectric,magnetic and optical properties of prepared samples were *** profiles reveal the formation of simple cubic spinel structure without any traceable *** average crystallite size lies within the range of 22–29 *** parameter decreases with increasing Ni *** temperature DC resistivity was recorded from 6:39×10^(5)to 3:79×10^(5)Ω*** dielectric constant(ε)and loss factor(tanδ)were decreased with increase of frequency while AC conductivity *** absorption peak occurred at three different frequency ranges at 570-577 cm^(-1),1635-1662 cm^(-1)and 3439–3448 cm^(-1).Magnetic properties were investigated by using vibrating sample magnetometer(VSM).Decreasing trends were observed for saturation magnetization(Ms),magnetic coercivity(Hc)and remanant magnetization(Mr)with the increase of Ni *** band gap(-2.70-2.79 eV)were calculated from diffuse reflectance data by using Kubelka–Munk function.

关键词： Sol-gel NiCuZn ferrite FTIR DC resistivity dielectric optical properties

A Simplified Model, Dynamic Analysis and Force Estimation for a Large-scale Orinthopter in Forward Flight Based on Flight Data

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Journal of Bionic Engineering 2020年第5期17卷 989-1008页

作者： mohammad Ali Amini Moosa Ayati mohammad Mahjoob School of Mechanical Engineering College of EngineeringUniversity of TehranNorth Kargar StreetTehranIran

Similarities and differences of a large-scale flapping-wing robot with fixed-wing UAVs in equations of motion,trim curves,and aerodynamic forces in forward flight are discussed in this paper and a simplified model for flapping flight is *** to the high Wing to Total Weight(WTW)ratio of large-scale omithopters,simple rigid body dynamics is not accurate enough for flight dynamics *** the other hand,the multi-body dynamics associated with flapping gives little insight into the behavior of the resulting model due to complexity of *** is also difficult to design proper controllers for such complicated *** this paper,the effects of different terms of multi-body equations of ornithopter on the estimated aerodynamic forces are studied via experimental flight data.A simpler but yet accurate set of equations is obtained by removing less effective terms from original *** presented model is in the form of normal aircraft equations plus some additional terms which can be used in different control and estimation *** addition,trim conditions of forward flight are extracted using several flight tests,and corresponding periodic behavior of states and forces are *** studies are applicable for identifying time-periodic models.

关键词： flapping wing robot bionic robot ornithopter trim condition analysis low-order modeling aerodynamic force estimation

An Unsupervised Writer Identification Based on Generating Clusterable Embeddings

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Computer Systems Science & Engineering 2023年第8期46卷 2059-2073页

作者： M.F.Mridha Zabir mohammad Muhammad Mohsin Kabir Aklima Akter Lima Sujoy Chandra Das Md Rashedul islam Yutaka Watanobe Department of Computer Science and Engineering American International University BangladeshDhaka1229Bangladesh Department of Computer Science&Engineering Bangladesh University of Business&TechnologyDhaka1216Bangladesh Department of Computer Science and Engineering University of Asia PacificDhaka1216Bangladesh Department of Computer Science and Engineering University of AizuAizu-Wakamatsu965-8580Japan

The writer identification system identifies individuals based on their handwriting is a frequent topic in biometric authentication and verification *** to its importance,numerous studies have been conducted in various *** have established several learning methods for writer identification including supervised and unsupervised ***,supervised methods require a large amount of annotation data,which is impossible in most *** the other hand,unsupervised writer identification methods may be limited and dependent on feature extraction that cannot provide the proper objectives to the architecture and be *** paper introduces an unsupervised writer identification system that analyzes the data and recognizes the writer based on the inter-feature relations of the data to resolve the uncertainty of the features.A pairwise architecturebased Autoembedder was applied to generate clusterable embeddings for handwritten text ***,the trained baseline architecture generates the embedding of the data image,and the K-means algorithm is used to distinguish the embedding of individual *** proposed model utilized the IAM dataset for the experiment as it is inconsistent with contributions from the authors but is easily accessible for writer identification *** addition,traditional evaluation metrics are used in the proposed ***,the proposed model is compared with a few unsupervised models,and it outperformed the state-of-the-art deep convolutional architectures in recognizing writers based on unlabeled data.

关键词： Writer identification pairwise architecture clusterable embeddings convolutional neural network

Determination of hemoglobin adduct of a musk xylene metabolite in trout as biomarker of exposure by gas chromatography mass spectrometry

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Journal of Environmental Sciences 2005年第6期17卷 989-992页

作者： mohammad Abdul KARIM mohammad Rezaul Department of Chemistry and Biochemistry Baylor University P.O. Box 97348 Waco TX 76798-7348 USADepartment of Biochemistry and Molecular Biology University of Rajshahi Rajshahi 6205 Bangladesh

Musk xylene（MX） is frequently used as fragrances in formulation of personal care products. Quantification of a bound 4-amino- MX（4-AMX） as cysteine adducts in trout hemoglobin（Hb） was made by gas chromatography-ion trap-mass spectrometry（GC/MS）. The Hb samples were collected from trout after 24 h exposure to MX at 10μg/g, and or menhaden oil（control）. The formation of cysteine-Hb adduct was observed from nitroso derivative of MX, released by alkaline hydrolysis. The released 4-AMX metabolite was extracted in n- hexane. The extract was then reduced by evaporation, and analyzed by GC/MS. When similar agreement of mass spectral features and retention time of 4-AMX were obtained in both standard and sample solutions, the presence of 4-AMX metabolite in the Hb was confirmed. The concentration of 4-AMX was found to be 3.1 × 10^-6 6.9 × 10^-6 mg/g in the Hb solution. Quantitation was made based on an internal standard, a calibration plot, and response factor. In the non-hydrolyzed and laboratory blank extracts, the 4-AMX metabolite was not detected. Additionally, coeluting and interfefing ions were observed in the biological samples.

关键词： biomarkers musk xylene metabolite Hb adducts fish exposure

Applicability of semi-destructive method to derive allometric model for estimating aboveground biomass and carbon stock in the Hill zone of Bangladesh

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Journal of Forestry Research 2020年第4期31卷 1235-1245页

作者： Hossain Mahmood mohammad Raqibul Hasan Siddique S.M.Zahirul islam S.M.Rubaiot Abdullah Henry Matieu Md.Zaheer Iqbal Mariam Akhter Forestry and Wood Technology Discipline Khulna UniversityKhulna 9208Bangladesh Forest Inventory Division Bangladesh Forest Research InstituteChittagong 4000Bangladesh Food and Agriculture Organization Rome 00153Italy Bangladesh Forest Department Bana bhabanAgargaonDhaka 1207Bangladesh

Biomass estimation using allometric models is a nondestructive and popular *** of an allometric model can influence the accuracy of biomass *** Forest Department initiated a nationwide forest inventory to assess biomass and carbon stocks in trees and *** relationship between carbon storage and sequestration in a forest has implications for climate change mitigation in terms of the carbon sink in *** part of the national forest inventory,we aimed to derive multi-species biomass models for the hill zone of Bangladesh and to determine the carbon concentration in tree components(leaves,branches,bark and stem).In total,175 trees of 14 species were sampled and a semi-destructive method was used to develop a biomass model,which included development of smaller branch(base dia<7 cm)biomass allometry and volume estimation of bigger branches and *** best model of leaf,branches,and bark showed lower values for adjusted R2(0.3152-0.8043)and model efficiency(0.436-0.643),hence these models were not recommended to estimate *** best fit model of stem and total aboveground biomass(TAGB)showed higher model efficiency 0.948 and 0.837,respectively,and this model was recommended for estimation of tree biomass for the hill zone of *** best fit allometric biomass model for stem was Ln(Stem)=-10.7248+1.6094*Ln(D)+1.323*Ln(H)+1.1469*Ln(W);the best fit model for TAGB was Ln(TAGB)=-6.6937+0.809*Ln(D^2*H*W),where DBH=Diameter at Breast Height,H=Total Height,W=Wood *** two most frequently used pan-tropical biomass models showed lower model efficiency(0.667 to 0.697)compared to our derived TAGB *** best fit TAGB model proved applicable for accurate estimation of TAGB for the hill zone of *** concentration varied significantly(p<0.05)by species and tree *** concentration(48-49%)of carbon was recorded in the tree stem.

关键词： Allometry Bangladesh Biomass Carbon Forest inventory

Retraction:Modeling Electrical Characteristics of a pn-Junction Silicon Solar Cell Using PSpice

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Smart Grid and Renewable Energy 2012年第2期3卷 133-138页

作者： mohammad Ziaur Rahman Shahidul islam Khan De- partment of Electrical and Electronic Engineering Bangladesh University of Engineering and Technology Dhaka Bangladesh. Department of Electrical and Electronic Engineering Ahsanullah University of Science and Technology Dhaka Bangladesh

Short Retraction Notice The article has been retracted due to the investigation of complaints received against it. The substantial portions of the text came from Luis Casta?er and Santigo Silvestre, " Modelling photovoltaic systems using PSpice".The scientific community takes a very strong view on this matter and we treat all unethical behavior such as plagiarism seriously. This paper published in Vol.3 No.2 133-138, 2012, has been removed from this site.

关键词： Solar Cell PSpice Short Circuit Current Quantum Efficiency Open Circuit Voltage Fill-Factor Efficiency

Experimental investigation of different brines imbibition influences on co-and counter-current oil flows in carbonate reservoirs

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Chinese Journal of Chemical Engineering 2021年第5期34卷 17-29页

作者： Pouyan Ahmadi mohammad Reza Aghajanzadeh Masoud Riazi mohammad Reza Malayeri mohammad Sharifi Enhanced Oil Recovery(EOR)Research Centre IOR/EOR Research InstituteShiraz UniversityShirazIran Helmholtz Centre for Environmental Research-UFZ LeipzigGermany Department of Petroleum Engineering Amirkabir University of TechnologyTehranIran Institut für Verfahrenstechnik und Umwelttechnik Technische Universität DresdenGermany

Imbibition of water,as wetting phase in oil-wet fractured carbonate reservoirs,plays a key role in fluid flow between matrix and fracture *** type of injected seawater and its chemistry would profoundly influence the imbibition *** this study,the impact of smart water(a brine that its ions have been adjusted to facilitate oil recovery)and low salinity water on co-and counter-current imbibition processes for oil-wet carbonate cores has been experimentally *** results show an increase of about 10% in oil recovery for co-and counter-currents for smart seawater imbibition compared to that of low salinity *** addition,as a result of the influence of co-and counter-current on each other,by co-current removal from one core face,the countercurrent in the other face would be intensified by as much as about 75%.A close examination of different lengths(5,7 and 9 cm)of carbonate cores with the same permeability revealed that by decreasing porous medium length,the amount of counter-current producing oil would be decreased so that in the 5 cm core,counter current oil production will not *** similar core lengths by increasing permeability,the share of counter current flow would be decreased approximately 18% since the capillary pressure could not overcome non-wetting phase viscous *** the role of matrix length along with a modified brine(which is designed according to the matrix mixture)strengthen the relevant mechanisms to have more oil production so that the higher thickness of matrix causes the higher amount of co-current oil producing and consequently more total recovery.

关键词： Smart water Co-current Counter current Wettability alteration Oil recovery

Analysis of Spray Evaporation in a Model Evaporating Chamber:Effect of Air Swirl

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Journal of Thermal Science 2023年第2期32卷 837-853页

作者： mohammad Sadegh ABEDINEJAD Department of Mechanical Engineering Faculty of EngineeringAlzahra UniversityTehranIran

Spray evaporation of liquid fuels in a turbulent flow is a common process in various engineering applications such as *** between fuel droplets(discrete phase)and fluid flow(continuous phase)have a considerable effect on liquid fuel *** this paper,both the single-and two-phase modeling of liquid fuel injection into a model evaporating chamber are *** influences of important issues such as turbulence models,coupling between gas phase and droplets,secondary break-up and air swirling on the current spray simulation are ***,the shear stress transport turbulence model,Taylor analogy break-up and two-way coupling models are applied to simulate the two-phase *** and spray of fuel droplets in hot air are modeled employing an Eulerian-Lagrangian *** current results show an acceptable agreement with the *** the fuel atomizer,bigger droplets are detected near the spray edge and minor droplets are situated in the *** increasing the droplets axial position,the droplets diameter decreases with a finite *** smaller droplets have a deeper penetration,but their lifetime is smaller and they evaporate sooner.A linear relation between penetration and lifetime of smaller droplets is *** droplet penetration and mean axial velocity of gas phase are observed for no air swirling *** effect of variation of swirl number on the lifetime of droplets is almost *** enhancing the swirl number,the uniformity of droplet size distribution is reduced and some large droplets are formed up in the domain.

关键词： secondary break-up droplet evaporation air swirling fuel spray gas-droplets coupling

A Time Dependent Inventory Model for Exponential Demand Rate with Constant Production Where Shelf-Life of the Product Is Finite

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Open Journal of Applied Sciences 2016年第1期6卷 38-48页

作者： mohammad Ekramol islam Shirajul islam Ukil Md. Sharif Uddin Department of Business Administration Northern University Dhaka Bangladesh Department of Mathematics Jahangirnagar University Savar Bangladesh

In this paper a time dependent inventory model is developed on the basis of constant production rate and market demands which are exponentially decreasing. It advances in quest of total average optimum cost considering those products which have finite shelf-life. The model also considers the small amount of decay. Without having any sort of backlogs, production starts. Reaching at the desired level of inventories, it stops production. After that due to demands along with the deterioration of the items it initiates its depletion and after certain periods the inventory gets zero. The decay of the products is level dependent. The objective of this paper is to find out the optimum inventory cost and optimum time cycle. The model has also been justified with proving the convex property and by giving a numerical example.

关键词： Production Inventory Shelf-Life Time Dependent Demand Class Production Rate

Mineralogical and sink-float studies of Jajarm low-grade bauxite

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 251-256页

作者： mohammad Zarbayani Esmaeil Jorjani Mirsaleh Mirmohammadi mohammad Taghi Shadloo mohammad Noaparast Science and Research Branch Islamic Azad University School of Mining Engineering University of Tehran Jajarm Alumina Company

Jajarm＇s bauxite deposits are mainly diasporic, and they have a low mass ratio of Al2O3/SiO2. It is necessary to increase the run-of-mine mass ratio before feeding the material to the Bayer process. Chemical analysis indicated that the low-grade bauxite sample from Jajarm contained 43.9wt% Al2O3 and 13.35wt% SiO2, resulting in a mass ratio of 3.29. According to mineralogical studies, the presence of aluminosilicate minerals such as kaolinite, illite, and quartz was the main reason for the decrease of the mass ratio. Microscopic observations revealed that, with the size reduction from -1000＋710 to -38 μm, the liberation degree of diaspore increased from 10% to 60%, and that of aluminosilicates increased from 20% to 85%. Heavy liquids with the densities of 2.8, 3.0, 3.2, and 3.4 g/cm3 were used to evaluate the heavy media separation in three sizes, i.e., -3350＋710, -710＋212, and -212＋125 μm. Laboratory studies confirm that the density of 3.2 g/cm3 can produce the concentrates （in sunk fractions） with recoveries of 89.09%, 91.24%, and 84.68% with the Al2O3/SiO2 mass ratios of 5.03, 5.16, and 5.15 for the -3350＋710, -710＋212, and -212＋ 125 μ m sizes, respectively.

关键词： bauxite diaspore aluminosilicate mass ratio heavy media