Different Attempt to Improve Friction Stir Brazing: Effect of Mechanical Vibration and Rotational Speed

Behrouz Bagheri,Mahmoud Abbasi,Farzaneh Sharif,Amin Abdollahzadeh 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9

A developed version of friction stir brazing (FSB) entitled friction stir vibration brazing (FSVB) was presented to fabricatelow carbon steel joint using %67wt Sn-%33wt Pb alloy as a braze metal. This attempt aims to analyze the role of mechanicalvibration and rotational speed on microstructure and mechanical behaviors of the brazed samples. Furthermore, the thermalanalysis, the thickness of intermetallic compounds (IMCs) layers, and void volume percentage at the joint interface werestudied. It was concluded that the temperature during the joining process increased and the coherency of the joint interfaceenhanced while FSVB was applied instead of FSB. In addition, the grains in the joint zone under the FSVB process weresmaller than those produced under the conventional FSB process. The results also showed that the mechanical performance,namely hardness, and shear strength increased and the thickness of the IMCs layer along with the void volume percentagein the brazed sample decreased as rotational speed increased from 850 to 1150 rpm. The results indicated that rotationalspeeds over 1150 rpm had detrimental effects on mechanical properties. This is related to the effect of high heat input andinduced temperature on brazing flow and filler-base metal interaction.

RBF Neural Network Sliding Mode Consensus of Multiagent Systems with Unknown Dynamical Model of Leader-follower Agents

Amin Sharafian,Vahid Bagheri,Wei Dong Zhang 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.2

This paper proposed a new methodology to cover the problem of consensus of multiagent systems with sliding mode control based on Radial Basis Function (RBF) neural network. First, neural network adopted to distinguish the uncertainties of the leader and follower agents then a sliding mode tracking controller is applied to force the follower agents to follow the leader’s time-varying states trajectory with the consensus error as small as possible. As the RBF neural network is adopted to approximate the uncertainties, the results can only achieve local consensus. Different from past literature, total error of consensus protocol is considering for sliding surface therefore the local stability of the whole multiagent system is provided meanwhile RBF neural network overcome the problem of unmodeled leader/follower agent dynamics. The weights of the neural networks updated adaptively directly commensurate with consensus error. The point is, there is absolutely no need to have information about dynamical model of the system. The merits of the proposed approach are consisting of consensus protocol robustness, fast error convergence to zero, and local stability of the closed loop multiagent system which is proved by Lyapunov direct method. The simulation results show promising performance of the proposed method on a chaotic system.

A Proposed Procedure for Progressive Collapse Analysis of Common Steel Building Structures to Blast Loading

Meysam Bagheri Pourasil,Yaghoub Mohammadi,Amin Gholizad 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.6

There is rising concern among researchers regarding the suitability of structural design for abnormal load resistance. Abnormal loading generated by a blast or impact can cause local damage to a structure that could affect the entire structural system. Structures must be designed to prevent such disproportional consequences. Research has focused on progressive collapse analysis of buildings, most of which are based on the alternative path method and the sudden removal of one or several columns. In this procedure, failure of elements adjoining to the removed columns under blast conditions are ignored, which can lead to an incorrect prediction of progressive collapse. The present study developed a procedure for progressive collapse analysis of common steel building structures subject to blast loading. A 3D numerical model for direct simulation of blast loading is proposed to study the real behavior of a 7-story building under blast loading. A blast load equivalent to 1 t of TNT was simulated at a distance of 4 m from the corner of the structure to assess the direct effect on the structure. The pressure of this blast at 4 levels of loading was applied to adjacent structural members and the structural response was examined and the exciting forces in the adjacent structural members of the blast site were compared. The results indicate that the potential for progressive collapse when assuming blast loading as the initial cause of failure will differ from results of common methods used for evaluation of progressive collapse and in methods that ignore the initial reason for progressive collapse.

Investigation of SiC Nanoparticle Size and Distribution Effects on Microstructure and Mechanical Properties of Al/SiC/Cu Composite during the FSSW Process: Experimental and Simulation

Behrouz Bagheri,Ali Shamsipur,Amin Abdollahzadeh,Seyyed Ehsan Mirsalehi 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4

In this work, aluminum-copper composites reinforced with 50 nm and 250 nm SiC particles are fabricated on the interfaceof sheets by friction stir spot welding for the first time. In addition, the finite element method is used to study visual andunderstand the temperature distribution and mechanical characteristics of the composite with different nanoparticle sizes. Micro stress/strain field mainly simulated the impacts of particle size and particle distribution in the matrix. Results showedthat large reinforcing particles lead to an increase in temperature distribution and grain size in the stir zone of the jointsample. It was also concluded that the addition of finer nanoparticle size causes higher shear tensile (5.4 MPa) and Von-Mises stress (260 MPa) in the workpiece due to higher homogeneous distribution and less agglomeration in the matrix. Inaddition, the thickness of the intermetallic compound (IMCs) layer at the interface of the joint interface was analyzed as SiCparticles with different sizes are used due to higher interaction and intermixing between materials. The stress distributionand equivalent plastic strain of particles in the stir zone, with the uniform distribution of reinforcing particles for lower size(50 nm), increased.

Advanced Approach to Modify Friction Stir Spot Welding Process

Behrouz Bagheri,Mahmoud Abbasi,Amin Abdollahzadeh,Hamid Omidvar 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.10

Nowadays, friction stir spot welding (FSSW) is used in automotive, rail vehicle construction, the aerospace industry, andelectrical industry. In the current research, a modified version of the FSSW process entitled friction stir spot vibration weldingwas introduced to join Al5083 specimens. The joining specimens were vibrated normal to the tool movement direction,while the joint position cooled by passing coolant through the fixture. Different characteristics of developed joint namelymicrostructure, mechanical properties, corrosion behavior were studied. The results showed that stir zone grain size decreasedsignificantly as the vibration was employed and the joint position was cooled. It was found that vibration enhanced thedynamic recrystallization and coolant decreased the grain growth. Both led to enhanced grain refinement in the stir zone. The results also indicated that shear strength and hardness of the weld region increased as the modified version of FSSWwas applied. Corrosion tests revealed that corrosion resistance increased as the modified method was applied.

Compound Heterozygosity for Two Novel SLC26A4 Mutations in a Large Iranian Pedigree with Pendred Syndrome

Nasrin Yazdanpanahi,Mohammad Amin Tabatabaiefar,Effat Farrokhi,Narges Abdian,Nader Bagheri,Shirin Shahbazi,Zahra Noormohammadi,Morteza Hashemzadeh Chaleshtori 대한이비인후과학회 2013 Clinical and Experimental Otorhinolaryngology Vol.6 No.4

Objectives. The aim of this study was to detect the genetic cause of deafness in a large Iranian family. Due to the importance of SLC26A4 in causing hearing loss, information about the gene mutations can be beneficial in molecular detection and management of deaf patients. Methods. We investigated the genetic etiology in a large consanguineous family with 9 deaf patients from Fars province of Iran with no GJB2 mutations. Initially, linkage analysis was performed by four DFNB4 short tandem repeat markers. The result showed linkage to DFNB4 locus. Following that, DNA sequencing of all 21 exons, their adjacent intronic sequences and the promoter of SLC26A4 was carried out for mutation detection. Results. Two novel mutations (c.863-864insT and c.881-882delAC) were identified in exon 7 of the gene, in both homozygous and compound heterozygous state in patients. Conclusion. Our results supported the importance of the SLC26A4 mutations in the etiology of hearing loss among the Iranian patients and therefore its mutation screening should be considered after GJB2 in the molecular diagnostics of hearing loss, especially when enlarged vestibular aqueduct or goiter is detected.

Evaluation of sHLA-G levels in serum of patients with prostate cancer identify as a potential of tumor marker

Mohammad Hassan Heidari,Abolfazl Movafagh,Mohammad Amin Abdollahifar,Shabnam Abdi,Mohamadreza Mashhoudi Barez,Hadi Azimi,Afshin Moradi,Amin Bagheri,Matineh Heidari,Jafar Hessam Mohseni,Maryam Tadayon 대한해부학회 2017 Anatomy & Cell Biology Vol.50 No.1

Prostate cancer is the most common cancer type in men and is the second cause of death, due to cancer, in patients over 50, after lung cancer. Prostate specific antigen (PSA) is a widely used tumor marker for prostate cancer. Recently, PSA is discovered in non-prostatic cancer tissues in men and women raising doubts about its specificity for prostatic tissues. PSA exists in low serum level in healthy men and in higher levels in many prostate disorders, including prostatitis and prostate cancer. Thus, a supplementary tumor marker is needed to accurately diagnose the cancer and to observe the patient after treatment. Recently, soluble human leukocyte antigen-G (sHLA-G) has been introduced as a new tumor marker for different cancer types, including colorectal, breast, lung, and ovary. The present descriptive-experimental study was carried out including patients with malignant prostate tumor, patients with benign prostate tumor, and a group of health men as the control group, as judged by an oncologist as well as a pathologist. After sterile blood sampling, sHLA-G was measured by enzyme-linked immunosorbent assay in each group. The data was then analyzed using one-way ANOVA. P≤0.05 was considered as statistically significant. The results showed that the mean of sHLA-G level was high in patients. Also, it was found that there was a significant difference in sHLA serum level between the three groups. The data revealed that sHLA-G can be a novel upplementary tumor marker in addition to PSA to diagnose prostate cancer.

Periodate activation by concurrent utilization of UV and US for the degradation of para-nitrophenol in water: A synergistic approach

Akbar Eslami,Fayyaz Mehdipour,Rouzan Feizi,Farshid Ghanbari,Kun-Yi Andrew Lin,Amin Bagheri,Soheila Madihi-Bidgoli 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.4

Para-nitrophenol (PNP) is a toxic compound widely used in various industries. The release of PNP into the environment not only threatens human health but the ecosystem. Hence, the treatment of contaminated water is necessary. Periodate (PI) is a new oxidant which is used for the generation of free radicals. In the current work, PI was concurrently activated by ultraviolet (UV) and ultrasound (US) to eliminate PNP from aqueous solution. The effects of operating parameters were studied and complete degradation of PNP was obtained in 30 min. The presence of ferrous ions increased the PNP degradation rate. Scavenging experiments confirmed that HO• and IO • 3 were corresponding agents of the PNP degradation, which the latter had a bold role. The performance of PI/UV/US was examined on real wastewater and the results showed that 70% of total phenol was removed during 60 min. The PNP degradation intermediate was recognized and a pathway of PNP degradation was proposed. Although PI/UV/US process is high energy consuming, its excellent performance can be a rational reason for the scaling up the process.

Enhanced degradation of 2,4-dichlorphenoxyacetic acid herbicide by CaO2 activated by Fe(II) and ultrasound irradiation: Practical insight and mineralization

Eslami Akbar,Mahdipour Fayyaz,Maleksari Hajar Sharifi,Varank Gamze,Ghasemi Seyed Mehdi,Nejatian Parisa,Bagheri Amin,Madihi-Bidgoli Soheila 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12

CaO2 was activated by Fe(II) and ultrasound (US) irradiation to degrade 2,4-dichlorphenoxyacetic acid (2,4-D) for the first time. Among transition metals (Fe, Cu, Mn and Co), Fe(II) had the best performance for the activation of CaO2. The impact of pH, CaO2 and Fe(II) concentration was studied, and under optimal situation ∼91% of 2,4-D was degraded during 60 min reaction time. The quenching experiments showed that the hydroxyl radical was the main factor for the destruction of 2,4-D while superoxide anions had a minor role. The bicarbonate ions and acid humic exhibited a strong inhibitory effect on the performance of CaO2/US/Fe(II) process. Carbon and chlorine mineralization of 2,4-D degradation was investigated; around 41% of C and 35% of Cl were mineralized during 60 min reaction time. The function of CaO2/US/Fe(II) process was studied on real drainage and other organic pollutants, and the results showed that the CaO2/US/Fe(II) process can be practical for water treatment. Finally, intermediates of 2,4-D degradation were identified, a pathway was proposed, and the toxicity of intermediates was assessed by ECOSAR software.