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RISS 인기검색어
- 검색키워드
- 저자 : Mohsen Askari (검색결과 4 건)
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Semi-active control of smart building-MR damper systems using novel TSK-Inv and max-min algorithms
Mohsen Askari,Jianchun Li,Bijan Samali 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.5
Two novel semi-active control methods for a seismically excited nonlinear benchmark building equipped with magnetorheological dampers are presented and evaluated in this paper. While a primary controller is designed to estimate the optimal control force of a magnetorheological (MR) damper, the required voltage input for the damper to produce such desired control force is achieved using two different methods. The first technique uses an optimal compact Takagi-Sugeno-Kang (TSK) fuzzy inverse model of MR damper to predict the required voltage to actuate the MR dampers (TSKFInv). The other voltage regulator introduced here works based on the maximum and minimum capacities of MR damper at each time-step (MaxMin). Both semi-active algorithms developed here, use acceleration feedback only. The results demonstrate that both TSKFInv and MaxMin algorithms are quite effective in seismic response reduction for wide range of motions from moderate to severe seismic events, compared with the passive systems and performs better than original and Modified clipped optimal controller systems, known as COC and MCOC.
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Mina Dehghan,Reza Miresmaeili,Mohsen Askari‑Paykani,Hamid Reza Shahverdi 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5
A novel severe plastic deformation is carried out on a medium Mn advanced high strength steel (AHSS) at both room andcryogenic temperatures which is called surface mechanical impact treatment (SMIT). After characterization, utilizing thedesign of experiment (DOE) program, it is obtained that how the SMIT parameters including time, voltage, and, shot diameteraffect the tensile test results of SMITed samples at room temperature (RT-SMITed). Microhardness profiles of SMITedsamples at cryogenic temperature (CT-SMITed) show more increase in microhardness than RT-SMITed ones up to thecenter of specimens. Additionally, the yield strength of CT-SMITed and RT-SMITed samples increases by 84% and 28% onaverage, respectively. The formation of mechanical twins, slip bands and, rhombic blocks improve both the microhardnessand yield strength of treated samples. The ultimate tensile strength (UTS) of all treated specimens decreases sharply (35%in RT-SMITed and 32% in CT-SMITed samples). According to DOE results, UTS has a negative correlation with voltageand based on fracture surface images, brittle fracture configurations increases with increasing voltage. The reason for thisobservation could be the precracks formed due to the deformation of detected MnS precipitates and the possibility of themartensite phase cracking during the SMIT process.
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Mohammad Amini,Komeil Nasouri,Gholamreza Askari,Mohsen Shanbeh,Akbar Khoddami 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3
This paper describes a study on the development of novel lightweight and highly flexible composites forelectromagnetic interference (EMI) shielding applications. The weft-knitted fabrics produced by using polyester/cotton,polyester/cotton-copper, and polyester/cotton-stainless steel composite yarns with metal deposition and without metaldeposition were tested to determine the EMI shielding effectiveness (SE). The surface structures of all composite fabricsamples were observed by stereomicroscope. The state of the presence of metal particles on the metal deposited compositefabric was studied by field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) analyzer. The EDX analyses confirmed the presence of metal particles, and the FESEM analyses revealed uniformly deposited metalparticles on the surface of composite fabrics. The EMI shielding was also evaluated using vector network analyzers in thefrequency range of 8-12 GHz for all samples. The highest value of EMI SE in this research for the composite fabric with themetal deposited sample was achieved to 19.53-23.95 dB. Moreover, the breathability and the durability of produced fabricswere characterized by air permeability, moisture regains, abrasion resistance, and washing fastness. The results of EMIshielding, durability, and breathability tests confirmed their potential for use as an excellent material for EMI shielding inwearable textiles for commercial applications.
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Hysteresis modeling for cyclic behavior of concrete-steel composite joints using modified CSO
Yang Yu,Bijan Samali,Chunwei Zhang,Mohsen Askari 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.2
Concrete filled steel tubular (CFST) column joints with composite beams have been widely used as lateral loading resisting elements in civil infrastructure. To better utilize these innovative joints for the application of structural seismic design and analysis, it is of great importance to investigate the dynamic behavior of the joint under cyclic loading. With this aim in mind, a novel phenomenal model has been put forward in this paper, in which a Bouc-Wen hysteresis component is employed to portray the strength and stiffness deterioration phenomenon caused by increment of loading cycle. Then, a modified chicken swarm optimization algorithm was used to estimate the optimal model parameters via solving a global minimum optimization problem. Finally, the experimental data tested from five specimens subjected to cyclic loadings were used to validate the performance of the proposed model. The results effectively demonstrate that the proposed model is an easy and more realistic tool that can be used for the pre-design of CFST column joints with reduced beam section (RBS) composite beams.
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