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Effect of earth reinforcement,soil properties and wall properties on bridge mSE walls

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Frontiers of Structural and Civil Engineering 2021年第5期15卷 1209-1221页

作者： Zaid mOmANI Eyosias BENEBERU Nur yazdani Department of Civil Engineering Al-Ahliyya Amman UniversityAmman 19328Jordan Bridgefarmer&Associates DallasTX 75234USA Department of Civil Engineering University of Texas at ArlingtonArlingtonTX 76019USA

mechanically stabilized earth(mSE)retaining walls are popular for highway bridge *** have precast concrete panels attached to earth *** panels are designed to have some lateral ***,in some cases,excessive movement and even complete dislocation of the panels have been *** this study,3-D numerical modeling involving an existing mSE wall was undertaken to investigate various wall *** effects of pore pressure,soil cohesion,earth reinforcement type and length,breakage/slippage of reinforcement and concrete strength,were *** showed that the wall movement is affected by soil pore pressure and reinforcement integrity and length,and unaffected by concrete *** cohesion has a minor effect,while the movement increased by 13–20 mm for flexible geogrid reinforced walls compared with the steel grid *** steel grid stresses were below yielding,while the geogrid experienced significant stresses without *** reinforcement may be used taking account of slippage resistance and wall *** steel grid is used,non-cohesive soil is recommended to minimize *** soil drainage is important for control of pore pressure.

关键词： mechanically stabilized earth walls precast concrete panels backfill soil finite element modeling earth reinforcement

Effects of Annealing on the Fabrication of Al-TiAl3 Nanocomposites Before and After Accumulative Roll Bonding and Evaluation of Strengthening mechanisms

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Acta metallurgica Sinica(English Letters) 2022年第4期35卷 636-650页

作者： Zohreh yazdani mohammad Reza Toroghinejad Hossein Edris Department of materials Engineering Isfahan University of Technology84156-83111 IsfahanIran

The strengthening mechanisms of Al-TiAl_(3) nanocomposite, fabricated using cold roll bonding, annealing, and accumulative roll bonding(ARB) on Al sheets sandwiching with pure Ti powder were investigated in the present study. With annealing at 590 ℃ for 2 h, TiAl_(3) intermetallic compound was formed. After subsequent ARB process up to 5 cycles, final composite consists of ultrafine Al grains of less than 500 nm with TiAl_(3) particles larger than 200 nm. The strength and hardness of the final composite are 2.5 and 3.5 times the initial values, with an ultimate tensile strength of 400 mPa, which is dominated by grain-boundary strengthening due to the ultrafine Al grains, and Orowan strengthening due to the small TiAl_(3) particles. For comparison, an alternative fabrication route of cold roll bonding–ARB–annealing was also studied. This study showed that annealing before ARB is a critical factor in producing an ultrafine grain structure containing TiAl_(3) particles.

关键词： Composite Annealing Strength microstructure Al

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

Smart component monitoring system increases the efficiency of photovoltaic plants

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Clean Energy 2023年第2期7卷 I0001-I0009,312页

作者： Hassan yazdani mehdi Radmehr Alireza ghorbani Department of Electrical Engineering Sari BranchIslamic Azad UniversitySariIran

Due to the increasing expansion of renewable energy,especially the widespread installation of solar power plants worldwide,to better exploit and increase the efficiency and quality of power generation,we need to closely monitor the performance of important components of the *** this study,using an innovative smart monitoring system and electronic sensors,we monitored compo-nents such as power in photovoltaic(PV)arrays in real time,including the phenomenon of hot spots as an example of power loss in PV *** of hot spots is very difficult to deal with in a large power *** results also demonstrated smart monitoring that increased detection speed and increased the efficiency rate per supervisory technician by≤36% compared with the previous ef-ficiency rate,which was 10% per technical staff,and increased the quality of the operation of each solar power *** this paper,meteorological data were coordinated with research data to validate the ***,to compare the results of using the smart monitoring method with the conventional observation method,a complete diagram of a 5-kW solar system in mATLAB■2018 was simulated and output diagrams were ***,to provide a comprehensive validation,our research results were com-pared with technical data obtained from a local 5-kW solar power plant located in Sari,Iran(36°33ʹ48″N,53°03ʹ36″E)with an average annual irradiation of 1490 kWh/m^(2).When the simulation results and research are analysed,it is clear that the smart and real-time monitoring approach brings various benefits to solar power plants.

关键词： photovoltaic power plant online monitoring efficiency solar cell power PV modules

Dry sliding wear of Ni alloyed austempered ductile iron

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China Foundry 2016年第5期13卷 361-367页

作者： E.Akbarzadeh Chiniforush m.A.Rahimi S.yazdani Faculty of materials Engineering Sahand University of Technology

measurements of dry sliding wear are presented for ductile irons with composition Fe-3.56C-2.67Si- 0.25mo-0.5Cu and Ni contents of 0.8 and 1.5 in wt.% with applied loads of 50, 100 and 150 N for austempering temperatures of 270, 320, and 370 ℃ after austenitizing at 870 ℃ for 120 min. The mechanical property measurements show that the grades of the ASTm 897m： 1990 Standard can be satisfied for the selected austempering conditions. The results show that wear resistance is independent of austempedng temperature with an applied load of 50 N, but there is a strong dependence at higher austempering temperatures with applied loads of 100 and 150 N. Observations indicate that wear is due to subsurface fatigue with cracks nucleated at deformed graphite nodules.

关键词： austempered ductile iron wear austenite ausferrite nickel

Impact of Perlator on the cooling liquid flow and hottest point temperature of superconducting windings in HTS transformer

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Superconductivity 2022年第3期3卷 97-105页

作者： mahdi mahamed mohammad yazdani-Asrami Vahid Behjat Akbar yazdani mojtaba Sharifzadeh Department of Electrical Engineering Azarbaijan Shahid Madani UniversityTabrizIran Propulsion Electrification&Superconductivity GroupJames Watt School of EngineeringUniversity of GlasgowGlasgowUK Department of Applied Sciences University of Quebec at ChicoutimiChicoutimiCanada Thermal Power Plant Research Center TabrizIran Fondazione Bruno Kessler TrentoItaly

The generated heat by the superconducting windings and the other parts such as current leads in transformer increases the hottest point temperature(HPT)and causes the high temperature superconducting(HTS)windings to *** to the properties of superconducting windings,reducing the HPT is of critical importance for the stable operation of the HTS *** cooling system of HTS transformers,not only provides the cryogenic temperature for the proper operation of the superconductors but also is responsible for dissipating the generated heat by the *** this paper,the effect of the angle of inlet pipes in cooling system was *** was a simple and effective solution which increases the heat transfer in liquid *** was shown that inlet angle has a significant effect on the flow turbulence and the windings *** Perlator is used as a lattice sheet which is installed inside the inlet valve and increases the turbulence of inlet flow of liquid nitrogen to increase heat transfer and reduce *** thermal analysis is obtained by finite element method using ANSYS Fluent *** influence of changing the inlet pipe angle and different structure of Perlator on heat transfer was investigated.

关键词： Cryogenic temperature Finite element method Heat transfer Perlator Superconducting transformer Turbulences

Wear Resistance of Two Nanostructural Bainitic Steels with Different Amounts of mn and Ni

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Acta metallurgica Sinica(English Letters) 2016年第6期29卷 587-594页

作者： Saman Ahmadi miab Behzad Avishan Sasan yazdani Faculty of materials Engineering Sahand University of Technology Department of materials Engineering Azarbaijan Shahid Madani University

Extremely valuable mechanical properties in combination with acceptable wear resistance can make nanostructural bainitic steels to be used extensively in different engineering and tribological applications. However, it is critical to characterize the contributed factors to investigate the wear response of these high-strength materials. This work aims to study the wear behavior of two nanostructural bainitic steels with different amount of austenite stabilizer elements mn and Ni. For this purpose, wear resistances of the materials were evaluated using the pin-on-disk method. The results indicated that the hardness of the sample is a critical factor affecting the tribological behavior, and the volume fraction and morphology of high-carbon retained austenite are also of considerable importance. It has also been demonstrated that transformation-induced plasticity effect during the wear test and oxide formation at worn surfaces are critical factors.

关键词： Nanostructural bainitic steel Wear Retained austenite TRIP

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

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