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Application of Bernstein polynomials for solving Fredholm integro-differential-difference equations

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Applied Mathematics(A Journal of Chinese Universities) 2022年第4期37卷 475-493页

作者： Esmail Hesameddini mehdi Shahbazi Department of Mathematics Sciences Shiraz University of TechnologyP.O.Box 71555-313ShirazIran

In this paper,the Bernstein polynomials method is proposed for the numerical solution of Fredholm integro-differential-difference equation with variable coefficients and mixed *** method is using a simple computational manner to obtain a quite acceptable approximate *** main characteristic behind this method lies in the fact that,on the one hand,the problem will be reduced to a system of algebraic *** the other hand,the efficiency and accuracy of the Bernstein polynomials method for solving these equations are *** existence and uniqueness of the solution have been ***,an estimation of the error bound for this method will be shown by preparing some ***,some numerical experiments are presented to show the excellent behavior and high accuracy of this algorithm in comparison with some other well-known methods.

关键词： Fredholm integro-differential-difference equation Bernstein polynomials existence and uniqueness error estimate

On the dynamically formed oxide films in molten Mg

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Journal of Magnesium and Alloys 2020年第1期8卷 219-230页

作者： Mohammad Mahdi Jalilvand mehdi Akbarifar mehdi Divandari Hassan Saghafian School of Metallurgy and Materials Engineering Iran University of Science and Technology(IUST)NarmakTehran16846-13114Iran

The so-called“Oxide/Metal/Oxide sandwich”method is one of the technique used to investigate the dynamic oxidation of metals which happens during the casting *** this study,characteristics of the oxide films formed on the molten magnesium in dynamic conditions have been investigated using the aforementioned *** air bubbles were released into the cast sample at the pressure of 0.2 atm through a quartz tube of 1 mm internal *** interface of two adjacent entrapped bubbles is considered as the Oxide/Metal/Oxide(OMO)*** sandwiches were characterized by the aid of the optical and scanning electron microscopy and also X-Ray diffraction *** different approaches,including measuring the width of the folds formed on the oxide films and the edge of the sandwiches,were used to estimate the thickness of the *** thicknesses were estimated to be in the range of 200 to 800 *** features such as fold,wrinkle,and crack were observed on the OMO *** the microscopic scale,the oxide films were rough and *** is attributed to the non-protective behavior of oxide *** XRD patterns indicated that the oxide films formed on the pure molten magnesium in dynamic conditions are crystallized MgO.

关键词： Dynamic oxidation Bifilm Magnesium Oxide films Casting defects

Semi-hot Stamping as an Improved Process of Hot Stamping

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Journal of Materials Science & Technology 2011年第4期27卷 369-376页

作者： Malek Naderi Mostafa Ketabchi Mahmoud abbasi Wolfgang Bleck Department of Mining and Metallurgy Amirkabir University of Technology Department of Ferrous Metallurgy RWTH-Aachen University

Reducing the forming load, deletion of springback, increasing the formability of sheets as well as producing high strength parts are the main reasons to apply hot stamping process. Hot stamping process and 22MnB5 steels are the state of the art process and grades, respectively; however novel processes and steel grades are under considerations. In the current research, behavior of the steel grade MSW1200 blanks under semi and fully hot stamping processes was characterized. During semi-hot stamping process, the blank was firstly heated to a temperature of about 650℃ and then formed and quenched in the die assembly, simultaneously. Microstructure and mechanical properties of semi and fully hot stamped blanks were studied and the results were compared with those of normally water/air quenched blanks. The hot stamped blanks attained the strength values as high as water quenched blanks. The highest ductility and consequently, the best formability were achieved for the blank which had been semi-hot stamped. It was concluded that for the mentioned steel, semi-hot stamping process could be considered as an improved thermo-mechanical process which not only guaranteed a high formability, but also led to ultra high strength values.

关键词： Semi-hot stamping Hot stamping MSW1200 steel Mechanical properties

Seismotectonics and consequences of the 1930s large earthquakes in eastern Mazandaran,north of Iran

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Journal of Mountain Science 2022年第2期19卷 513-528页

作者： Mohsen EHTESHAMI-MOINABADI Ehsan abbasi Ali SAKET Department of Sedimentary Basins and Petroleum Shahid Beheshti UniversityTehran ***Iran Natural Disaster Research Institute Tehran ***Iran

Early in the 1930 s,two relatively large earthquakes(Kosout,magnitude 6.8,and Talarrud,magnitude 5.8)shook the eastern Mazandaran,northern *** the historical and instrumental seismic activity of the eastern region of Mazandaran,little is known about the status of seismotectonics and consequences of these *** paper presents a compilation of available data from early reports of these earthquakes with new structural,geomorphic and local data on the effects of this earthquake,especially co-seismic landslides and liquefaction,to assess the seismotectonics and probable causative faults of the *** is proposed that the close times of occurrence of two earthquakes might be due to local loading or triggering effect of the first earthquake on the second *** many other instrumental earthquakes in the Central Alborz,it is difficult to find the exact causative faults of important earthquakes,however the Qadikola,Chachkam or North Alborz Fault have the potential of producing Kosout earthquake and the Lalehband fault is more promising for Talarrud ***,the structural complexity of the area is also discussed in the form of a hybrid tectonic *** this model,the boundary zone of thick-skinned and active thin-skinned domains has more structural complexity than outer ***-Badeleh Shahvar pop-up structure is bounded by major faults with thick-skinned deformation *** role of older inherited fault structures and their interaction with low-slope Neogene thrusts driven from north to south by crustal tectonics and deformation is ***-seismic landslides and rock falls have great potential to be investigated in the Alborz Range for identification of prehistoric earthquakes.

关键词： Seismotectonics Co-seismic Landslide Alborz Active Fault Earthquake

Analytical investigation of γN→N^*,Δ^* transition helicity amplitudes

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Chinese Physics C 2020年第7期44卷 157-166页

作者： Farhad Zolfagharpour mehdi Aslanzadeh Department of Physics Faculty of SciencesUniversity of Mohaghegh ArdabiliP.O.Box 179ArdabilIran

We study the structure of nonstrange baryons by analytically calculating the electromagnetic transition helicity amplitudes of the nucleon andΔ*** employ an improved hypercentral constituent quark model and obtain the corresponding eigenenergies and eigenfunctions in closed ***,we calculate the transverse and longitudinal helicity amplitudes for nucleon andΔ*** comparison of evaluated observables and experimental data indicates good agreement between the proposed model and available data.

关键词： helicity amplitudes nucleon and delta resonances transition form factors

Under the influence of crowding effects:Stability,bifurcation and chaos control for a discrete-time predator-prey model

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International Journal of Biomathematics 2019年第4期12卷 185-213页

作者： Muhammad Aqib abbasi Qamar Din Department of Mathematics University of the Poonch Rawalakot Pakistan

The interaction between predators and preys exhibits more complicated behavior under the influence of crowding effects. By taking into account the crowding effects, the qualitative behavior of a prey-predator model is investigated. Particularly, we examine the boundedness as well as existence and uniqueness of positive steady-state and stability analysis of the unique positive steady-state. Moreover, it is also proved that the system undergoes Hopf bifurcation and flip bifurcation with the help of bifurcation theory. Moreover, a chaos control technique is proposed for controlling chaos under the influence of bifurcations. Finally, numerical simulations are provided to illustrate the theoretical results. These results of numerical simulations demonstrate chaotic long-term behavior over a broad range of parameters. The presence of chaotic behavior in the model is confirmed by computing maximum Lyapunov exponents.

关键词： Prey-predator model stability analysis boundedness flip bifurcation Hopfbifurcation chaos control

EEG-Based Neonatal Sleep Stage Classification Using Ensemble Learning

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Computers, Materials & Continua 2022年第3期70卷 4619-4633页

作者： Saadullah Farooq abbasi Harun Jamil Wei Chen School of Computing Edinburgh Napier UniversityEdinburgh EH105DTUK Center for Intelligent Medical Electronics Department of Electronic EngineeringFudan University200433China Department of Computer Engineering Jeju National UniversityJejusiJeju Special Self-Governing Province63243Korea

Sleep stage classification can provide important information regarding neonatal brain development and *** annotation,using polysomnography(PSG),is considered as a gold standard for neonatal sleep stage ***,visual annotation is time consuming and needs professional *** this reason,an internet of things and ensemblebased automatic sleep stage classification has been proposed in this study.12 EEG features,from 9 bipolar channels,were used to train and test the base classifiers including convolutional neural network,support vector machine,and multilayer *** and stacking ensembles are then used to combine the outputs for final *** proposed algorithm can reach a mean kappa of 0.73 and 0.66 for 2-stage and 3-stage(wake,active sleep,and quiet sleep)classification,*** proposed network works as a semi-real time application because a smoothing filter is used to hold the sleep stage for 3 *** high-performance parameters and its ability to work in semi real-time makes it a promising candidate for use in hospitalized newborn infants.

关键词： Internet of things machine learning convolutional neural network artificial intelligence

Influence of Aluminum Content on Mechanical Properties and Cold Workability of Fe-33Ni-15Co Alloy

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Journal of Iron and Steel Research International 2012年第2期19卷 67-72页

作者： M Safavi S M abbasi R Mahdavi Department of Materials Science and Engineering Semnan University Advanced Materials Research Laboratory (AMRL) Department of Mechanical Engineering K.N. Toosi University of Technology Department of Materials Science Azad University

The influence of 0.01% to 0. 25% of Aluminum content （in mass percent） on the mechanical properties and cold workability of low thermal expansion Fe-33Ni-15Co sheets in the annealed and hot rolled condition was investigated. Addition of Al up to 0.15 % resulted in the increase of ductility and tougianess and improvement of workability. Besides, achievement of fine grain structure and increase in the amount of annealing twins caused ductility to improve. Addition of Al higher than 0.15 % led to the increase in oxidation reaction during melting process and to refine under argon atmosphere. This caused the volume fraction of Al containing inclusions to increase and consequently the ductility and toughness to decrease.

关键词： Fe-33Ni-15Co alloy A1 content mechanical property cold workability

A comparative study between friction stir processing and friction stir vibration processing to develop magnesium surface nanocomposites

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International Journal of Minerals,Metallurgy and Materials 2020年第8期27卷 1133-1146页

作者： Behrouz Bagheri Mahmoud abbasi Amin Abdollahzadeh Amir Hossein Kokabi Department of Mining and Metallurgy Amirkabir University of TechnologyTehranIran Faculty of Engineering University of KashanRavandi Blvd.KashanIran Department of Materials Science and Engineering Sharif University of TechnologyTehranIran Institute of Materials Engineering and Advanced Processes Department of Mining and MetallurgyAmirkabir University of TechnologyTehranIran

Friction stir processing(FSP)can be used to improve surface *** this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium *** this technique,the workpiece is vibrated normal to the processing *** results illustrated that compared with the FSP method,the FSVP caused a better homogeneous distribution of SiC particles in the *** results also showed that matrix grains of friction stir vibration processed(FSV-processed)samples((26.43±2.00)μm)were finer than those of friction stir processed(FS-processed)specimens((39.43±2.00)μm).The results indicated that the ultimate tensile strength(UTS)of FSV-processed specimens(361.82 MPa)was higher than that of FS-processed specimens(324.97 MPa).The higher plastic strain in the material during FSVP,due to workpiece vibration,resulted in higher dynamic recrystallization,and consequently,finer grains were *** elongation and formability index of the FSV-processed specimen(16.88%and 6107.52 MPa·%,respectively)were higher than those of the FS-processed sample(15.24%and 4952.54 MPa·%,respectively).Moreover,the effects of FSVP were also found to intensify as the vibration frequency increased.

关键词： friction stir processing friction stir vibration processing surface composite mechanical properties microstructure