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Materials Sciences and Applications 2013年第11期4卷 667-678页

作者： Haniyeh Fayazfar abdollah afshar Abolghasem Dolati Department of Materials Science and Engineering Sharif University of Technology Tehran Iran

An efficient method has been developed to synthesize well-aligned multi-walled carbon nanotubes (MWCNTs) on a conductive Ta substrate by chemical vapour deposition (CVD). Free-standing MWCNTs arrays were functionalized through electrochemical oxidation with the formation of hydroxyl and carboxyl functional groups. Using a new oven drying technique, we demonstrate that the unidirectionally aligned and laterally spaced geometry of the CNT arrays can be retained after being subjected to each step of electrochemical modification. Samples were analyzed by using a field emission scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transformed infrared (FTIR) and Raman spectroscopy. Useful electrochemical methods for the synthesis of various gold nanostructures onto the aligned MWCNTs were then presented for the first time. The results demonstrated that flowerlike nanoparticle arrays, nanosheets and nanoflowers were obtained on the aligned CNTs under different experimental conditions. These kinds of aligned-CNT/Au nanostructures hybrid materials introduced by these efficient and simple electrochemical methods could lead to development of a new generation device for ultrasensitive catalytic and biological application.

关键词： Chemical Vapour Deposition Vertically Aligned Carbon Nanotube Electrochemical Techniques Nanostructures Nanoflowers

A New Highly Sensitive Optical Sensor Based on Congo-Red for the Determination of Thorium(Ⅳ) in Aqueous Solution

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Journal of Analysis and Testing 2023年第4期7卷 416-424页

作者： abdollah Yari Samaneh Penhani Faculty of Chemistry Lorestan UniversityKhorramabad 68151-44316Iran

This essay explores the use of the sol-gel method based on the Congo-red reagent as an effective approach to create an optical sensor for the detection and tracking of Thorium(Ⅳ)(Th^(4+)).Upon exposure to a Th^(4+)-containing solution,the sensor exhibits significant absorption signal change that linearly correlates with Th^(4+)ion concentration across a wide *** is capable of detecting Th^(4+)ion in the linear dynamic range of 1.7×10^(-8)to 1.1×10^(-3)mol/L,with a detection limit of 5.3×10^(-9)mol/*** optode’s exceptional porous network,created through the sol-gel technique,contributes to its commendable performance,reliable repeatability,improved sensitivity,swift response time,and discerning selectivity.

关键词： Congo-red Optical sensor Sol-gel Thorium(IV)

A new solution to estimate the time delay on the topographic site using time domain 3D boundary element method

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Earthquake Engineering and Engineering Vibration 2020年第3期19卷 611-623页

作者： Reza Tarinejad Mohsen Isari abdollah Sohrabi-Bidar Faculty of Civil Engineering University of TabrizTabrizIran School of Geology College of ScienceUniversity of TehranTehranIran

This study focuses on investigating spatial variation of ground motion that has great influence on the dynamic behavior of the large structures located on the surface *** of the most effective parameters on the spatial variation of ground motion is the difference between the arrival time of seismic waves in different points located on the *** this research,a three-dimensional model of the Pacoima Dam site is *** time domain 3 D boundary element method is used to apply non-uniform excitation at the dam *** model is subjected to vertically propagating incident SH and P *** time delay can be characterized by calculating the value of the time delay for which the cross-correlation between two records is ***,to obtain the time delay in a topographic site,a function considering effective parameters such as the height from the canyon base,wave velocity and predominant frequency,is ***,a code was developed for generating the spatially variation of seismic ground *** results show that the proposed functions have an acceptable accuracy in estimating the time delay to generate non-uniform ground motion.

关键词： delay boundary element

A Stable Analytical Solution Method for Car-Like Robot Trajectory Tracking and Optimization

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IEEE/CAA Journal of Automatica Sinica 2020年第1期7卷 39-47页

作者： Keyvan Majd Mohammad Razeghi-Jahromi abdollah Homaifar School of Computing Informaticsand Decision Systems EngineeringArizona State UniversityTempeAZ 85281 USA ABB Corporate Research Center RaleighNC 27606 USA Department of Electrical and Computer Engineering North Carolina A&T State UniversityGreensboroNC 27403 USA

In this paper, the car-like robot kinematic model trajectory tracking and control problem is revisited by exploring an optimal analytical solution which guarantees the global exponential stability of the tracking error. The problem is formulated in the form of tracking error optimization in which the quadratic errors of the position, velocity, and acceleration are minimized subject to the rear-wheel car-like robot kinematic model. The input-output linearization technique is employed to transform the nonlinear problem into a linear formulation. By using the variational approach, the analytical solution is obtained, which is guaranteed to be globally exponentially stable and is also appropriate for real-time applications. The simulation results demonstrate the validity of the proposed mechanism in generating an optimal trajectory and control inputs by evaluating the proposed method in an eight-shape tracking scenario.

关键词： Global asymptotic stability input-output linearization optimal control trajectory tracking

Undirected Zero-Divisor Graphs and Unique Product Monoid Rings

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Algebra Colloquium 2019年第4期26卷 665-676页

作者： Ebrahim Hashemi abdollah Alhevaz LABokut Faculty of Mathematical Sciences Shahrood University of Technology P.O.Box:316-***ShahroodIran 不详

Let R be an associative ring with identity and Z^*(K)be its set of non-zero *** undirected zero-divisor graph of R、denoted byΓ(R),is the graph whose vert ices are the non-zero zero-divisors of R、and where two distinct verticesγand s are adjacent if and only ifγs=0 or sγ=*** dist ance bet ween vertices a and b is the length of the shortest path connecting them,and the diameter of the graph,diam(Γ(R)),is the superimum of these *** this paper,first we prove some results aboutΓ(R)of a semi-commutative ring ***,for a reversible ring R and a unique product monoid M、we prove 0≦diam(Γ(R))

关键词： zero-divisor graph diameter semi-commutative ring unique product monoid monoid ring

Effects of Mn and Cu on the Mechanical Properties of a High Strength Low Alloy NiCrMoV Steel

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Journal of Materials Science & Technology 2005年第4期21卷 470-474页

作者： A.abdollah-zadeh M.Belbasy Department of Materials Engineering Tarbiat Modarres University P.O. Box 14115-143 Tehran IranDepartment of Materials Engineering Tarbiat Modarres University P.O. Box 14115-143 Tehran Iran

The present study focuses on the effects of Mn and Cu on the mechanical properties, in particular, strength and toughness of a low alloy steel containing Ni, Cr, Mo and V. Specimens with different amounts of Mn （0.23%-0.85%）and Cu （0.15%-0.45%） were cast and forged, and then austenitized at 870℃ for 1h, followed by oil quenching. All specimens were tempered at 650℃ for 1h. The results show that as the amounts of Mn and Cu increase respectively from 0.35% to 0.85% and from 0.15% to 0.45%, the yield and tensile strength increase. The highest impact energies were observed in the specimen with 0.35% Mn and in the specimen with 0.25% Cu. The impact energy decreases with increasing the Mn and Cu from 0.35% to 0.85% and from 0.25% to 0.45%, respectively. Furthermore, the variation of Mn and Cu does not cause a considerable change in the tempered martensite microstructure. The optimum strength and toughness is observed in 0.35% Mn containing steel and in the 0.25% Cu containing steel.

关键词： NiCrMoV steel Cu Mn Tensile strength Impact energy

Effect of Strain Rate on the Ferrite Grain Refinement in a Low Carbon Nb-Ti Microalloyed Steel during Low Temperature Deformation

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Journal of Materials Science & Technology 2005年第6期21卷 851-855页

作者： B.Eghbali A.abdollah-zadeh Department of Materials Engineering Tarbiat Modarres University P.O. Box 14115-143 Tehran Iran

Grain refinement is one of the effective methods to develop new generation low carbon microalloyed steels possessing excellent combination of mechanical properties. The microstructural evolution and ferrite grain refinement at the deformation temperature of 865℃, above Ar3, with different strain rates were investigated using single pass isothermal hot compression experiments for a low carbon Nb-Ti microalloyed steel. The physical processes that occurred during deformation were discussed by observing the optical microstructure and analyzing the true stress-true strain responses. At strain rates of 0.001 and 0.01s^-1, there is no evidence of work hardening behavior during hot deformation and strain-induced transformation （SIT） leads to dynamic flow softening in flow curves. Optical microscopy observation shows that ultrafine and equiaxed ferrite with grain sizes of 2μm can be obtained by applying deformation with strain rate of 0.1 s^-1 due to SIT just after deformation. Furthermore, increasing the strain rate from 0.001 to 0.1 s^-1 reduces both the grain size of the equiaxed ferrite and the amount of deformed ferrite.

关键词： Low carbon microalloyed steel Hot compression Grain refinement Strain induced transformation

Stabilizing controller design for nonlinear fractional order systems with time varying delays

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Journal of Systems Engineering and Electronics 2021年第3期32卷 681-689页

作者： AZIZI abdollah FOROUZANFAR Mehdi Department of Electrical Engineering Ahvaz BranchIslamic Azad UniversityAhwaz 61349-37333Iran

To deal with stabilizing of nonlinear affine fractional order systems subject to time varying delays,two methods for finding an appropriate pseudo state feedback controller are *** the first method,using the Mittag-Lefler function,Laplace transform and Gronwall inequality,a linear stabilizing controller is derived,which uses the fractional order of the delayed system and the upper bound of system nonlinear *** the second method,at first a sufficient stability condition for the delayed system is given in the form of a simple linear matrix inequality(LMI)which can easily be ***,on the basis of this result,a stabilizing pseudo-state feedback controller is designed in which the controller gain matrix is easily computed by solving an LMI in terms of delay *** results show the effectiveness of the proposed methods.

关键词： fractional order nonlinear system time varying delay state feedback control linear matrix inequality(LMI) stabilizing

Liquation cracking in the heat-affected zone of IN939 superalloy tungsten inert gas weldments

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International Journal of Minerals,Metallurgy and Materials 2020年第6期27卷 764-773页

作者： Hassan Kazempour-Liasi Mohammad Tajally Hassan abdollah-Pour Faculty of Materials and Metallurgical Engineering Semnan UniversitySemnanIran

The main aim of this study was to investigate liquation cracking in the heat-affected zone(HAZ)of the IN939 superalloy upon tungsten inert gas welding.A solid solution and age-hardenable filler metals were further *** the pre-weld heat-treated samples,upon solving the secondaryγ′particles in the matrix,primaryγ′particles in the base metal grew to"ogdoadically diced cubes"of about 2μm in side *** pre-weld heat treatment reduced the hardness of the base metal to about HV *** studies using optical and fieldemission scanning electron microscopy revealed that the IN939 alloy was susceptible to liquation cracking in the *** constitutional melting of the secondary,eutectic,and Zr-rich phases promoted the liquation cracking in the *** microstructure of the weld fusion zones showed the presence of fine spheroidalγ′particles with sizes of about 0.2μm after the post-weld heat treatment,which increased the hardness of the weld pools to about HV 350 and 380 for the Hastelloy X and IN718 filler metals,*** of a suitable solid solution filler metal could partially reduce the liquation cracking in the HAZ of IN939 alloy.

关键词： superalloy tungsten inert gas weld heat-affected zone liquation cracking

Enhancing the Robustness of Visual Object Tracking via Style Transfer

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Computers, Materials & Continua 2022年第1期70卷 981-997页

作者： abdollah Amirkhani Amir Hossein Barshooi Amir Ebrahimi School of Automotive Engineering Iran University of Science and TechnologyTehran16846-13114Iran School of Electrical Engineering and Computing The University of NewcastleCallaghan2308Australia

The performance and accuracy of computer vision systems are affected by noise in different *** numerous solutions and algorithms have been presented for dealing with every type of noise,a comprehensive technique that can cover all the diverse noises and mitigate their damaging effects on the performance and precision of various systems is still *** this paper,we have focused on the stability and robustness of one computer vision branch(i.e.,visual object tracking).We have demonstrated that,without imposing a heavy computational load on a model or changing its algorithms,the drop in the performance and accuracy of a system when it is exposed to an unseen noise-laden test dataset can be prevented by simply applying the style transfer technique on the train dataset and training the model with a combination of these and the original untrained *** verify our proposed approach,it is applied on a generic object tracker by using regression *** method’s validity is confirmed by testing it on an exclusive benchmark comprising 50 image sequences,with each sequence containing 15 types of noise at five different intensity *** OPE curves obtained show a 40%increase in the robustness of the proposed object tracker against noise,compared to the other trackers considered.

关键词： Style transfer visual object tracking robustness corruption