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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

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

Corrosion and wear resistance of coatings produced on AZ31 Mg alloy by plasma electrolytic oxidation in silicate-based K2TiF6 containing solution:Effect of waveform

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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

Microstructure of shear-induced thixoformed Al-4.5Cu-1.5Mg alloy via RAP and SSTT processes

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China Foundry 2017年第4期14卷 297-303页

作者： Siamak Nikzad Hossein Ashuri Mahdi Shafizadeh keyvan Ferasat Department of Materials Science and Engineering Sharif University of Technology TehranIran

In this research, the effect of the thixoforming temperature on the microstructure and mechanical properties was investigated in the thixoforming of the feedstock produced by the RAP(recrystallization and partial melting) and SSTT(semi-solid thermal transformation) processes for Al-4.5Cu-1.5Mg alloy. In the RAP process, the percentage reduction in area was approximately 35%. Thixoforming was done at 610, 620, and 630 °C. Globular microstructure was observed at all temperatures and conditions. The minimum average globule size was 39 μm, and it was obtained in the thixoforming of the feedstock produced by the RAP process in the section of 4 mm in diameter at 620 ° C after applying shear. Its corresponding compressive strength was-877.44 MPa. The maximum average globule size was 136 μm, and it was obtained in the thixoforming of the feedstock produced by the SSTT process in the section of 10 mm in diameter at 630 °C before applying shear. Its corresponding compressive strength was-769.18 MPa. The finest and most spherical globules, as well as the highest compressive strength were obtained at 620 °C in both RAP and SSTT states.

关键词： thixoforming RAP SSTT aluminium alloys

Transformer components impact on compatibility of measured PDs:comparison of IEC60270 and RF methods

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High Voltage 2019年第1期4卷 33-40页

作者： keyvan Firuzi Mehdi Vakilian B.Toan Phung Trevor Blackburn Electrical Engineering Department and Centre of Excellence in Power System Management and Control Sharif University of TechnologyTehranIran School of Electrical Engineering&Telecommunications University of New South WalesSydneyAustralia

Power transformer partial discharge signal measurement using Radio Frequency method has advantages over IEC 60270‘apparent charge’measurement method for online monitoring due to greater immunity against external ***,the lack of a well-defined calibration relationship between the two methods is main disadvantage of RF *** measurements,using these two methods,carried out on various transformer PD source models,in laboratory,to investigate main parameters that affect the relationship of results of these two *** this paper,factors that influence this relationship are classified into three groups:(i)type of PD sources,(ii)transformer windings as PD signal transmitter,and(iii)the inner structure of the ***,the relationship between these two methods has been investigated for some simple types of PD ***,by adding the winding structure model to the void,which is the PD source,its impact on each measurement method and the relationship between them have been *** impact of inner structure on the relation between the two methods is compensated through a formula which is proposed as a means for calibration of the RF partial discharge measurement *** to compensate for internal insulating system effects more research is required.

关键词： winding disadvantage adding

Wet-Cupping Is Effective on Persistent Nonspecific Low Back Pain: A Randomized Clinical Trial

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Chinese Journal of Integrative Medicine 2019年第7期25卷 502-506页

作者： Mohsen Mardani-Kivi Reza Montazar Mohammad Azizkhani keyvan Hashemi-Motlagh Department of Orthopedic Guilan University of Medical Sciences Rasht Iran General Practitioner Traditional Medicine Specialist Tehran Iran Orthopedic Research Center Rasht Iran

Objective: To compare the possible effects of wet-cupping therapy with conventional therapy on persiste nt non specific low back pain (PNSLBP). Methods: In this ran domized clinical trial, 180 participa nts with the mean age of 45 ±10 years old, who had been suffering from PNSLBP were randomly assigned to wet-cupping and conventional groups using random blook. The wet-cupping group was treated with two separate sessions (4 weeks in total) on the inter-scapular and sacrum area. In the conventional group, patients were conservatively treated using rest (6 weeks) and oral medicati ons (3 weeks). The primary and the sec on dary outcome were the qua ntity of disability using Oswestry Disability Index (ODI), and pain intensity using Visual Analogue Scale (VAS), respectively. Results: There was no significant difference in demographic characteristics (age, gender, and body mass index) between the two groups (P>0.05). Therapeutic effect of wet-cupping therapy was comparable to conventional treatment in the 1st month follow-up visits (P<0.05). The functional outcomes of wet-cupping at the 3rd and 6th month visits were significantly increased compared to the conventional group. Final ODI scores in the wet-cupping and conventional groups were 16.7 ±5.7 and 22.3 ±4.5, respectively (P<0.01). Conclusion: Wet-cupping may be a proper method to decrease PNSLBP without any conventional treatment. The therapeutic effects of wet-cupping can be longer lasting than conventional therapy.(Registration No. IRCT2013021672741).

关键词： low back pain chronic wet-cupping therapy traditi onal medici ne Chin ese medici ne alter native medicine conservative treatment randomized clinical trial