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RISS 인기검색어
- 검색키워드
- 저자 : Afshin Kalantari (검색결과 2 건)
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Experimental and Numerical Study of a Seismic Rotating Mass Damper (RMD) in an Isolated Floor
Afshin Kalantari,Reihane Shafie Panah 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.4
Negative stiffness has shown a capable characteristic in reduction of seismic response of structures. In this paper a passive Rotating Mass Damper (RMD) with negative stiffness characteristic, which was conceptually introduced in an earlier study, has been employed experimentally and numerically on an isolated floor to protect the building content during strong ground motions. The equipment was assumed as a rigid block on the isolated floor. The RMD devices force results indicate the negative stiffness characteristic of the damper. It was also observed that the RMD could increase the natural period of the system up to 50 percent without increasing the mass or reducing the stiffness. A numerical model of a seven storey building was employed to investigate the seismic response of the isolation floor in fourth storey. Two RMD models with different specifications and a viscous damper providing 10 percent of critical damping were applied in the study. Seven ground motion records were selected from PEER ground motion database. The time history analysis results indicate that RMD dampers show acceptable performance in terms of reducing both acceleration up to 40% and displacement responses up to 68% simultaneously in comparison with the viscous damper under the applied ground motions. The model was also analyzed employing seven artificial seismic waves. The results in this part also show the capability of the damper model in generating negative stiffness characteristics and a successful performance during excitation.
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Babak Kakavandi,Ahmad Jonidi Jafari,Roshanak Rezaei Kalantary,Hamed Gharibi,Anvar Asadi,Ali Azari,Ali Akbar Babaei,Afshin Takdastan 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.10
Discharging the effluents of textile wastewaters into potable water resources can endanger the ecosystem, due to their reactivity, toxicity, and chemical stability. In this research, the application of powder activated carbon modified with magnetite nanoparticles (PAC-MNPs) as an adsorbent for removal of reactive dyes (Reactive black 5 (RB5) and reactive red 120 (RR120)) was studied in a batch system. The adsorption performance was evaluated as a function of temperature, contact time and different adsorbent and adsorbate concentrations. The levels of factors were statistically optimized using Box-Behnken Design (BBD) from the response surface methodology (RSM) to maximize the efficiency of the system. The adsorption process of both dyes was fit with the pseudo-second order kinetic and Langmuir isotherm models. The identified optimum conditions of adsorption were 38.7 oC, 46.3 min, 0.8 g/L and 102mg/L for temperature, contact time, adsorbent dose, and initial dyes concentration, respectively. According to the Langmuir isotherm, the maximum sorption capacities of 175.4 and 172.4mg/g were obtained for RB5 and RR120, respectively. Thermodynamics studies indicated that the adsorption process of the reactive dyes was spontaneous, feasible, and endothermic. After five cycles, the adsorption efficiency was around 84 and 83% for RB5 and RR120, respectively. A high value of desorption was achieved, suggesting that the PAC-MNPs have a good potential in regeneration and reusability, and also can be effectively utilized in industrial applications. PAC-MNPs also show a good anti-interference potential for removal of reactive dyes in dye-industry wastewaters.
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