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Journal of Magnesium and Alloys 2022年第9期10卷 2574-2587页

作者： Maryam Rahmati keyvan raeissi Mohammad Reza Toroghinejad Amin Hakimizad Monica Santamaria Department of Materials Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Yekta Mobaddel Pars Co. Science and Technology CampusYazd UniversityYazd 89158-18411Iran Dipartimento di Ingegneria Università di PalermoViale Delle ScienzeEd.690128PalermoItaly

In this research,plasma electrolytic oxidation coatings were prepared on AZ31 Mg alloy in a silicate-based solution containing K_(2)TiF_(6) using bipolar and soft sparking waveforms with 10,20,and 30%cathodic duty *** coatings displayed a net-like surface morphology consisted of irregular micro-pores,micro-cracks,fused oxide particles,and a sintered *** to the incorporation of TiO_(2) colloidal particles and the cathodic pulse repair effect,most of the micro-pores were ***-term corrosion performance of the coatings was investigated using electrochemical impedance spectroscopy during immersion in 3.5 wt.%NaCl solution up to 14 *** coating grown by the soft sparking waveform with a 20%cathodic duty cycle having the lowest porosity(6.2%)and a sharp layer concentrated in F element at the substrate/coating interface shows the highest corrosion *** friction coefficient of this coating has remained stable during the sliding even under 5 N normal load,showing relatively higher wear resistance than other *** coating produced using the equivalent unipolar waveform,as the reference specimen,showed the highest friction coefficient and the lowest wear resistance despite its highest micro-hardness.

关键词： Plasma electrolytic oxidation Pulsed waveforms AZ31 Mg alloy Dipotassium titanium hexafluoride Corrosion resistance Wear resistance

Incorporation mechanism of colloidal TiO_(2) nanoparticles and their effect on properties of coatings grown on 7075 Al alloy from silicate-based solution using plasma electrolytic oxidation

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Transactions of Nonferrous Metals Society of China 2021年第12期31卷 3659-3676页

作者： Mehri HASHEMZADEH keyvan raeissi Fakhreddin ASHRAFIZADEH Amin HAKIMIZAD Monica SANTAMARIA Department of Materials Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Yekta Mobaddel Pars Co. Science and Technology CampusYazd UniversityYazd 89158-18411Iran Dipartimento di Ingegneria Universitàdi PalermoViale Delle ScienzeEd.690128PalermoItaly

Plasma electrolytic oxidation(PEO)was applied using a pulsed unipolar waveform to produce Al_(2)O_(3)−TiO_(2) composite coatings from sol electrolytic solutions containing colloidal TiO_(2) *** sol solutions were produced by dissolving 1,3,and 5 g/L of potassium titanyl oxalate(PTO)in a silicate *** electron microscopy,energy dispersive spectrometry,X-ray diffraction,and Raman spectroscopy were applied to characterizing the *** behavior of the coatings was investigated using polarization and impedance *** results indicated that TiO_(2) enters the coating through all types of micro-discharging and is doped into the alumina *** higher level of TiO_(2) incorporation results in the decrease of surface micro-pores,while the lower incorporation shows a reverse *** was revealed that the higher TiO_(2) content makes a more compact outer layer and increases the inner layer thickness of the *** measurements revealed that the coating obtained from the solution containing 3 g/L PTO exhibits higher corrosion performance than that obtained in the absence of *** coating produced in the absence of PTO consists of γ-Al_(2)O_(3),δ-Al_(2)O_(3) and amorphous phases,while α-Al_(2)O_(3) is promoted by the presence of PTO.

关键词： Al alloy Al_(2)O_(3)−TiO_(2)coating plasma electrolytic oxidation potassium titanyl oxalate corrosion resistance

Self-repairing AlO-TiOcoatings fabricated through plasma electrolytic oxidation with various cathodic pulse parameters

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Transactions of Nonferrous Metals Society of China 2023年

作者： Mehri Hashemzadeh keyvan raeissi Fakhreddin Ashrafizadeh Frank Simchen Amin Hakimizad Monica Santamaria Thomas Lampke Department of Materials Engineering， Isfahan University of Technology Materials and Surface Engineering Group， Institute of Materials Science and Engineering， Chemnitz University of Technology Yekta Mobaddel Pars Co.， Science and Technology Campus， Yazd University Dipartimento di Ingegneria， Università di Palermo， Viale Delle Scienze

The influence of cathodic pulse parameters was evaluated on PEO coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate (PTO) using pulsed bipolar waveforms with various cathodic duty cycles and cathodic current densities. The coatings were characterized by SEM， EDS， and XRD. EIS was applied for investigating the electrochemical properties. It was observed that the increase of cathodic duty cycle and cathodic current density from 20% and 6 A dm-2to 40% and 12 A dm-2enhances the growth rate of the inner layer from 0.22 μm min-1to 0.75 μm min-1. Adding PTO into the bath showed a fortifying effect on influence of the cathodic pulse and the mentioned change of cathodic pulse parameters resulted in an increase of the inner layer growth rate from 0.25 to 1.10 μm min-1. Based on EDS analysis， Si and Ti were incorporated dominantly in the upper parts of the coatings. XRD technique merely detected γ-Al2O3， and there were no detectable peaks related to Ti and Si compounds. However， the EIS results confirmed that the incorporation of Ti4+into alumina changed the electronic properties of the coating. The coatings obtained from the bath containing PTO using the bipolar waveforms with a cathodic duty cycle of 40% and current density values higher than 6 A dm-2showed highly appropriate electrochemical behavior during 8 months of immersion due to an efficient repairing mechanism. Regarding the effects of studied parameters on the coating properties， the roles of cathodic pulse parameters and PTO in the PEO process were highlighted.

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Self-repairing Al_(2)O_(3)-TiO_(2)coatings fabricated through plasma electrolytic oxidation with various cathodic pulse parameters

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Transactions of Nonferrous Metals Society of China 2024年第10期34卷 3326-3343页

作者： Mehri HASHEMZADEH keyvan raeissi Fakhreddin ASHRAFIZADEH Frank SIMCHEN Amin HAKIMIZAD Monica SANTAMARIA Thomas LAMPKE Department of Materials Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Materials and Surface Engineering Group Institute of Materials Science and EngineeringChemnitz University of TechnologyChemnitz 09107Germany Yekta Mobaddel Pars Co. Science and Technology CampusYazd UniversityYazd 89158-18411Iran Dipartimento di Ingegneria Universitàdi PalermoViale Delle ScienzeEd.690128PalermoItaly

The influence of cathodic pulse parameters was evaluated on plasma electrolytic oxidation(PEO)coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate(PTO)using pulsed bipolar waveforms with various cathodic duty cycles and cathodic current *** coatings were characterized by SEM,EDS,and *** was applied to investigate the electrochemical *** was observed that the increase of cathodic duty cycle and cathodic current density from 20%and 6 A/dm^(2) to 40%and 12 A/dm^(2) enhances the growth rate of the inner layer from 0.22 to 0.75μm/*** PTO into the bath showed a fortifying effect on influence of the cathodic pulse and the mentioned change of cathodic pulse parameters,resulting in an increase of the inner layer growth rate from 0.25 to 1.10μm/*** on EDS analysis,Si and Ti were incorporated dominantly in the upper parts of the *** technique merely detectedγ-Al_(2)O_(3),and there were no detectable peaks related to Ti and Si ***,the EIS results confirmed that the incorporation of Ti^(4+)into alumina changed the electronic properties of the *** coatings obtained from the bath containing PTO using the bipolar waveforms with a cathodic duty cycle of 40%and current density values higher than 6 A/dm^(2) showed highly appropriate electrochemical behavior during 240 d of immersion due to an efficient repairing *** the effects of studied parameters on the coating properties,the roles of cathodic pulse parameters and PTO in the PEO process were highlighted.

关键词： Al_(2)O_(3)-TiO_(2)coating plasma electrolytic oxidation potassium titanyl oxalate electrochemical impedance spectroscopy

阴极脉冲参数对等离子体电解氧化制备自修复Al2O3-TiO2涂层的影响（英文）

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Transactions of Nonferrous Metals Society of China 2024年第10期 3326-3343页

作者： Mehri HASHEMZADEH keyvan raeissi Fakhreddin ASHRAFIZADEH Frank SIMCHEN Amin HAKIMIZAD Monica SANTAMARIA Thomas LAMPKE Department of Materials Engineering Isfahan University of Technology Materials and Surface Engineering Group Institute of Materials Science and EngineeringChemnitz University of Technology Yekta Mobaddel Pars Co. Science and Technology Campus Yazd University Dipartimento di Ingegneria Università di Palermo

在含草酸钛钾（Potassium titanyl oxalate, PTO）的硅酸盐电解液中采用不同阴极占空比和阴极电流密度的脉冲双极波形，在7075铝合金上生长等离子电解氧化（Plasma electrolytic oxidation, PEO）涂层，研究阴极脉冲参数对PEO涂层的影... 详细信息

在含草酸钛钾（Potassium titanyl oxalate, PTO）的硅酸盐电解液中采用不同阴极占空比和阴极电流密度的脉冲双极波形，在7075铝合金上生长等离子电解氧化（Plasma electrolytic oxidation, PEO）涂层，研究阴极脉冲参数对PEO涂层的影响。通过扫描电子显微镜、能量色散X射线光谱（EDS）和X射线衍射（XRD）对涂层进行了表征。使用电化学阻抗谱（Electrochemical impedance spectroscopy, EIS）研究其电化学性能。结果表明，当阴极占空比和阴极电流密度分别从20%和6 A/dm2增加到40%和12 A/dm2时，内层的生长速率从0.22μm/min提高到0.75μm/min。向电解液中加入PTO增强了阴极脉冲的影响，由此产生的阴极脉冲参数的变化使得内层生长速率从0.25μm/min增加到1.10μm/min。EDS分析结果表明，Si和Ti主要分布在涂层的上部。XRD仅检测到γ-Al2O3，未检测到与Ti和Si化合物相关的峰。然而，EIS结果证实，Ti4+掺入氧化铝改变了涂层的电性能。在含有PTO的电解液中使用40%阴极占空比和大于6 A/dm2电流密度的双极波形获得的涂层，在240 d的浸泡期间表现出优异的电化学行为，这归因于有效的修复机制。关于研究参数对涂层性能的影响，强调了阴极脉冲参数和PTO在PEO过程中的作用。

关键词： Al2O3-TiO2涂层等离子电解氧化草酸钛钾电化学阻抗谱

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

A Kernel Function Based Interior-Point Methods for Solving P_*(κ)-Linear Complementarity Problem

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Acta Mathematica Sinica,English Series 2010年第9期26卷 1761-1778页

作者： M.Reza PEYGHAMI keyvan AMINI Department of Mathematics K. N. Toosi University. of Technology School of Mathematics Institute for Research in Fundamental Sciences (IPM) Department of Mathematics Faculty of Sciences Razi University

In this paper, motivated by the complexity results of Interior Point Methods （IPMs） for Linear Optimization （LO） based on kernel functions, we present a polynomial time IPM for solving P.（a）-linear complementarity problem, using a new class of kernel functions. The special case of our new class was considered earlier for LO by Y. Q. Bai et al. in 2004. Using some appealing properties of the new class, we show that the iteration bound for IPMs matches the so far best known theoretical iteration bound for both large and small updates by choosing special values for the parameters of the new class.

关键词： Linear complementarity problem interior-point methods large and small update methods polynomial complexity

Potato Responds to Salt Stress by Increased Activity of Antioxidant Enzymes

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Journal of Integrative Plant Biology 2009年第12期51卷 1095-1103页

作者： keyvan Aghaei Ali Akber Ehsanpour Setsuko Komatsu National Institute of Crop Science Tsukuba 305-8518 Japan Department of Biology Faculty of Sciences University of Isfahan Isfahan *** Iran

To understand the response of potato to salt stress, antioxidant enzyme activities and ion content were analyzed for a sensitive and a tolerant cultivar. Nodal cuttings of the tolerant cultivar, Kennebec, and the sensitive cultivar, Concord, were exposed to media without or with 30, 60, 90 or 120 mmol/L NaCI for 4 weeks. On exposure to NaCI, the length and fresh and dry weight of both shoots and roots of Concord showed greater decrease than those of Kennebec. The decrease in shoot growth was more severe than that of the root for both cultivars. The K^＋ content of shoots and roots of both cultivars was reduced in a dose-dependent manner by exposure to NaCl; the Na^＋ content increased. Activities of ascorbate peroxidase, catalase and glutathione reductase were increased in NaCl-exposed shoots of Kennebec; the corresponding activities in NaCI-exposed shoots of Concord were decreased. Roots of both cultivars showed similar changes in the activities of these enzymes on exposure to NaCI. These studies established that enzyme activities in Concord shoots are inversely related to the NaCI concentration, whereas those in Kennebec do not show a dose dependency, which is also the case for the roots of both cultivars. Our findings suggest that an increase in activity of antioxidant enzymes, such as ascorbate peroxidase, catalase and glutathione reductase, can contribute to salt tolerance in Kennebec, a salt resistant cultivar of potato.

关键词： antioxidant enzyme ion content potato salt resistant cultivar salt stress.

Seismic vulnerability assessment of urban buildings and traffic networks using fuzzy ordered weighted average

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Journal of Mountain Science 2019年第3期16卷 677-688页

作者： Yasaman ASADI Najmeh Neysani SAMANY keyvan EZIMAND Department of Remote Sensing and GIS Faculty of GeographyUniversity of Tehran Remote Sensing and GIS Center Faculty of Earth ScienceUniversity of Shahid Beheshti

Urban buildings and urban traffic network are considered as the vital arteries of cities which have particular effects especially after the crisis in the search and rescue operations. The aim of this study is to determine the vulnerability of urban areas especially, buildings and traffic networks using multicriteria geographic information systems and decisionmaking methods. As there are many effective criteria on the seismic vulnerability that they have uncertain and vague properties, the method of this paper is applying fuzzy ordered weighted average(OWA) to model the seismic vulnerability of urban buildings and traffic networks in the most optimistic and pessimistic states. The study area is district 6 of Tehran that is affected by the four major faults, and thus will be threatened by the earthquakes. The achieved results illustrated the vulnerability with different degrees of risk levels including very high, high, medium, low and very low. The results show that in the most optimistic case 14% and in the pessimistic case 1% of buildings tolerate in very low vulnerability. The vulnerability of urban street network also indicates that in the optimistic case 12% and in the pessimistic case at most 9% of the area are in appropriate condition and the North and NorthEast of the study area are more vulnerable than South of it.

关键词： Earthquake Vulnerability Assessment Urban buildings Traffic network Multi-Criteria Decision Analysis(MCDA) Fuzzy-OWA

Image compression based on spatial redundancy removal and image inpainting

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第2期11卷 92-100页

作者： Vahid BASTANI Mohammad Sadegh HELFROUSH keyvan KASIRI Department of Electrical and Electronic Engineering Shiraz University of Technology

We present an algorithm for image compression based on an image inpainting method. First the image regions that can be accurately recovered are located. Then, to reduce the data, information of such regions is removed. The remaining data besides essential details for recovering tile removed regions are encoded to produce output data. At the decoder, an inpainting method is applied to retrieve removed regions using information extracted at the encoder. The image inpainting technique utilizes partial differential equations （PDEs） for recovering information. It is designed to achieve high performance in terms of image compres- sion criteria. This algorithm was examined for various images. A high compression ratio of 1：40 was achieved at an acceptable quality. Experimental results showed attainable visible quality improvement at a high compression ratio compared with JPEG.

关键词： Edge extraction Image compression Image inpainting Spatial redundancy