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Effect of nodule count and austempering heat treatment on segregation behavior of alloying elements in ductile cast iron

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China Foundry 2016年第3期13卷 217-222页

作者： E.Akbarzadeh Chiniforush N.Iranipour s.yazdani Faculty of Materials Engineering Sahand University of Technology Deakin University Institute for Technology Research and Innovation

The equilibrium partition ratio, k, has been measured for Mn, Mo, si, Ni and Cu in a ductile iron with composition(wt.%): 3.45 C, 0.25 Mn, 0.25 Mo, 2.45 si, 0.5Ni and 0.5Cu with different nodule counts obtained from different section sizes of13, 25, 75 mm in the as cast, austenitized(at 870 °C for times 1, 4 and 6 hours) and austempered(at 375 °C for times 1 to 1,440 min) samples. Results show that Mn and Mo segregate positively at cell boundaries, but si, Ni and Cu concentrate in an inverse manner in the vicinity ofgraphite nodules and there is a depletion ofthese elements at cell boundaries. segregation curves for Ni and Cu are more smooth than for si. Carbide formation has been observed at cell boundaries. Based on the results, the partition ratios for all elements decrease with increasing the nodule count. More carbide with coarser morphology has been observed in the microstructure with a lower nodule count. Austenitization for a longer time can decrease partition ratio, but cannot eliminate it entirely. Increasing the austenitization temperature has the same effect. Austenitizing parameters have no significant effect on carbides volume fraction. The kinetics ofaustempering is faster in higher nodule counts and subsequently better mechanical properties including higher ductility, strength and toughness have been observed for all austempering conditions studied.

关键词： segregation ductile iron austenitization austempering

An Investigation on Rotating Bending Fatigue Behavior of Nanostructured Low-Temperature Bainitic steel

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Acta Metallurgica sinica(English Letters) 2014年第2期27卷 233-238页

作者： B.R.shendy M.N.Yoozbashi B.Avishan s.yazdani Faculty of Materials Engineering Sahand University of Technology University of Applied science and Technology Faculty of Engineering Azarbaijan Shahid Madani University

The aim of this work is to investigate the fatigue behavior of a new class of nanostructured, low-temperature bainitic steels, where rotating bending fatigue tests were conducted on samples isothermally transformed at 300, 250, and 200 ℃, after which, fracture surfaces were examined using scanning electron microscopy. Results showed that, fatigue limits of about 820, 945, and 1,005 MPa were achieved for the samples transformed at each transformation temperature, respectively. Moreover, according to the sEM micrographs, secondary crack initiation was observed in the high carbon retained austenite blocks for samples transformed at 300 ℃ and at the interface of blocky austenite-bainitic ferrite for samples transformed at 250 and 200 ℃.

关键词： Fatigue Bainitic ferrite Retained austenite Fractography

Co-electrodeposition and properties evaluation of functionally gradient nickel coated ZrO_2 composite coating

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Transactions of Nonferrous Metals society of China 2018年第1期28卷 66-76页

作者： B.BOsTANI N.PARVINI AHMADI s.yazdani R.ARGHAVANIAN Faculty of Materials Engineering Sahand University of Technology Department of Mechanical Engineering Tabriz Branch Islamic Azad University

For the first time,functionally electroless nickel plated ZrO2(NCZ)graded Ni-NCZ composite coating has been successfully co-electrodeposited from a bath with gradually increasing of stirring *** showed that co-electrodeposition in a bath with stirring rate of250r/min results in the maximum co-electrodeposited particle content and the best particle *** produce NCZ graded Ni-NCZ composite coating,the stirring rate was continuously increased from0to250r/*** electroplated coating had a continuous gradient increasing of co-electrodeposited NCZ content from substrate towards the *** results showed that with increasing the co-electrodeposited NCZ particles content in Ni matrix,microhardness increases from interface towards the surface of the *** crystallite size of Ni matrix and higher co-electrodeposited hard particles content were recognized as the reasons of microhardness *** test revealed that the functionally graded composite coating shows more excellent adhesion to the substrate compared with the ordinary distributed Ni-NCZ on the same *** result is attributed to lower mechanical mismatch between coating and substrate in the functionally graded composite coating with respect to the uniformly distributed *** results of wear resistance measurements reveal that wear resistance of functionally graded Ni-NCZ is higher than that of ordinary distributed composite coating.

关键词： co-electrodeposition functionally graded composite coating microhardness wear resistance adhesion

Evaluating innovation ecosystem resiliency using agent-based modeling and systems dynamics

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Journal of safety science and Resilience 2024年第2期5卷 204-221页

作者： soheila Abdi Mehdi yazdani Esmaeil Najafi Department of Industrial Engineering Science and Research BranchIslamic Azad UniversityTehranIran Department of Industrial Engineering Qazvin BranchIslamic Azad UniversityQazvinIran

Evaluating the resilience of the innovation ecosystem to maintain its performance,in the sense of resistance to disruption and recovery after it,has recently received more *** studies have been conducted to model different ecosystems and evaluate their ***,modeling the innovation ecosystem from a holistic perspective and performing a quantitative assessment of its resilience have received less *** paper models the innovation ecosystem holistically and evaluates its resilience index using a quantitative approach through five main *** the first step,a case study related to the innovation ecosystem of Iran's Ministry of Energy,called the Power Innovation Ecosystem,is modeled by combining system dynamics and agent-based *** validating the model in the second step,the disruption of the loss of experts is investigated in the third step,and all possible actions to recover each actor are *** the fourth step,the performance of the ecosystem is simulated before and after the disruption using the data gathered in the previous ***,resilience is calculated in two different ways in the fifth *** improvement solutions are also suggested when considering that the resilience index of the innovation ecosystem is at a medium *** research may assist policymakers in observing the resilience level of the innovation ecosystem based on the proposed *** applying strategic changes to this model,they can determine the effects of their policies and make the most appropriate decisions to increase the resilience of the innovation ecosystem.

关键词： Resilience index innovation ecosystem system dynamics Agent-based modeling

Applying the spectral stochastic finite element method in multiple-random field RC structures

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Frontiers of structural and Civil Engineering 2022年第4期16卷 434-447页

作者： Abbas.yazdani Civil Engineering Department University of Sistan and BaluchestanZahedan 98167-45845Iran

This paper uses the spectral stochastic finite element method(ssFEM)for analyzing reinforced concrete(RC)beam/slab *** doing so,it presents a new framework to study how the correlation length of a random field(RF)with uncertain parameters will affect modeling uncertainties and reliability *** considers:1)different correlation lengths for uncertainty parameters,and 2)dead and live loads as well as the elasticity moduli of concrete and steel as a multi-dimensional RF in concrete *** show the ssFEM’s efficiency in the study of concrete structures and to evaluate the sensitivity of the correlation length effects in evaluating the reliability,two examples of RC beams and slabs have been *** to the results,the RF correlation length is effective in modeling uncertainties and evaluating reliabilities;the longer the correlation length,the greater the dispersion range of the structure response and the higher the failure probability.

关键词： uncertainty spectral stochastic finite element method correlation length reliability assessment reinforced concrete beam/slab

synergistic effect of seawater's parameters on the corrosion rate of the austenitic stainless steel 304

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Acta Metallurgica sinica(English Letters) 2010年第3期23卷 161-170页

作者： s.Atashin M.Pakshir A.yazdani Department of Materials science and Engineering Shiraz University

In this article the corrosion rate of the austenitic stainless steel type 304, under the synergistic effect of environmental factors has been assessed via potentiodynamic polarization ***, velocity, pH and temperature are the factors which induce effects on the corrosion rate of the considered *** analysis is applied using the full two-level factorial experimental design method, which results in the contribution value of each parameter in changing the quantity of average corrosion rate in both individual and synergistic *** this quantitative analysis, qualitative analysis has been used to predict the variation *** two analyses show the important role of the synergistic action, which changes the variation direction of corrosion rate and the contribution percentage of each parameter in varying the value of corrosion *** both these analyses can show the magnitude and quality of each parameter＇s effect, which is remarkably valuable in marine applications.

关键词： stainless steel 304 Environmental parameters seawater corrosion synergistic effect

Effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron

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China Foundry 2007年第2期4卷 120-123页

作者： s. yazdani M. Ardestani Faculty of Materials Engineering Sahand University of TechnologyTabrizIRAN

The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325℃and 400℃after austenitizing at 875℃and 950℃. The sub-zero treatments were carried out by cooling down the samples to -30℃, -70℃and -196℃. The changes in volume fraction of austenite and mechanical properties were determined after cooling to each temperature. The austenite volume fraction of samples which were austenitized at 875℃and austempered at 325℃remained unchanged, whilst it reduced in samples austenitized at 950℃and 875℃for austempering temperature of 400℃. In these specimens, some austenite transformed to martensite after subzero cooling. Mechanical property measurements showed a slight increase in strength and hardness and decrease in elongation and toughness due to this transformation behavior.

关键词： austempered ductile iron austenite sub-zero cooling martensitic transformation ausferrite

Recent progress on in situ characterizations of electrochemically intercalated transition metal dichalcogenides

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Nano Research 2019年第9期12卷 2126-2139页

作者： sajad yazdani Milad Yarali Judy J. Cha Department of Mechanical Engineering and Materials science Yale UniversityNew HavenCT 06511USA Energy sciences Institute Yale University West CampusWest HavenCT 06516USA

Layered transition metal dichalcogenides(TMDCs)have been extensively studied owing to their unique physical and chemical *** van der Waals(vdW)interact!ons betwee n the stacki ng layers of TMDCs allow intercalati on of various species including mono vale nt alkali,divale nt alkaline earth and multivale nt metal ions,zero-vale nt transiti on metals,as well as orga nic molecules,all of which can drastically alter fun dame ntal properties of the *** urge to understa nd the phe nomena and the desire to exploit them for applicati ons have inspired a great deal of investigations.A large portion of the mystery has been unveiled over the past decade of intense research;however,many questions remain open and require further *** review is concerned with investigations on structural and electronic evolution of TMDCs drive n by electrochemically con trolled in tercalati ***,we aim to survey the rece nt adva nces and experime ntal platforms for mon itoring the in tercalati on processes in situ by utilizi ng nano *** additi on,several in quiries and prospects are outlined in a broader con text for future ave nues of studies.

关键词： transition metal dichalcogenides electrochemical intercalation in situ characterizations transmission electron microscopy(TEM) magnetotransport measurements

Provincial clustering of malaria in Iran between 2005 and 2014

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Asian Pacific Journal of Tropical Medicine 2020年第4期13卷 162-168页

作者： Vahid Moqarabzadeh Ahmad Ali Enayati Ahmad Raeisi Fatemeh Nikpour Jamshid yazdani Charati Department of Biostatistics&Epidemiology School of HealthMazandaran University of Medical SciencesSariIran Medical Entomology Mazandaran University of Medical SciencesSariIran Department of Medical Entomology and Vector Control School of Public HealthTehran University of Medical SciencesTehranIran Department of Environmental Chemical Pollutants and Pesticides Institute for Environmental ResearchTehran University of Medical SciencesTehranIran Department of Biostatistics Health Sciences Research CenterAddiction InstituteMazandaran University of Medical SciencesSariIran

Objective: To reveal the provincial clustering of malaria in Iran between 2005 and 2014 based on the epidemiologic factors and the climatic indicators affecting the disease. Methods: This was a descriptive-analytical study using malaria and meteorological data from the Malaria Elimination Programme of the Ministry of Health and Medical Education and National Meteorological Organization. After standardization, the aggregate data was used to produce 10-year means for each province. The data analysis included grouping the provinces with respect to factors using hierarchical clustering method and Kruskal-Wallis test to examine the difference between clusters using sPss ver.23. Results: The hierarchical clustering stratified the provinces' in 5 clusters. Kruskal-Wallis H test revealed a significant difference in the incidence rate per 100000 population (P=0.001), male gender (P=0.001), Iranian nationality (P=0.001), Afghan nationality (P=0.003), Pakistani nationality (P=0.001), urban residence (P=0.006), rural residence (P=0.004), autochthonous cases (P=0.007), average minimum temperature (P=0.001), average maximum temperature (P=0.007), average relative humidity (P=0.011), average pressure level (P=0.038), prevailing wind direction (P=0.023), average wind speed (P=0.031) and average precipitation sum (P=0.002) among the clusters. Conclusions: The results of this study and stratification of the provinces could help health policy makers to better manage malaria by allocating resources accordingly.

关键词： Malaria Cluster analysis Iran