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Fast Seismic Life Cycle Cost Optimization of Steel Moment Frames to Improve Seismic Performance
Hossein Mirzaei,Kiarash Nasserasadi 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.3
This study presents a fast method of Life Cycle Cost (LCC) optimization of structures. One of the main obstacles to implementation of seismic lice cycle cost optimization is the time-consuming process of evaluating the possibility of failure of the structure. To overcome this restriction, in the proposed approach, the probability of failure is estimated using fragility functions. A fast method for developing the fragility function was employed in this paper to reduce the computation time. Two well-studied frames, adopted from the literature, were studied to demonstrate the implementation of the methodology. A comparison of results with previous studies indicates that a reasonable increase in the initial cost substantially reduces damage and life-cycle costs of the structure. It also significantly improves the seismic performance of structures. The proposed method can be employed to design more reliable and economical structures.
Intrinsic kinetics of the Fischer-Tropsch synthesis over an impregnated cobalt-potassium catalyst
Hossein Atashi,Mohsen Mansouri,Seyyed Hossein Hosseini,Mohammad Khorram,Ali Akbar Mirzaei,Masoud Karimi,Ghobad Mansouri 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3
The optimal amount of 15 wt%Co/10 wt%K/Al2O3 catalyst was prepared using the impregnation technique in order to study the kinetics of the Fischer-Tropsch synthesis. The rate of synthesis was measured in a fixed-bed micro reactor with H2/CO feed ratio of 1-3 and space velocity in the range of 2,700-5,200 h−1 under reactor pressure of 8 bar and a temperature range of 210-240 oC. The experimental data were best fitted by a Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach rate in the form of −rCO=(k2K1PCOPH2)/(1+K1PCO). Furthermore, the data were fitted fairly well by a power law equation in the form of −rCO=kPCO 1.32PH21.42. The activation energies for LHHW approach model and power law equation were obtained as 138.5 kJ/mol and 87.39 kJ/mol, respectively.
Mehdi Shiva,Hossein Atashi,Farhad Farshchi Tabrizi,Ali Akbar Mirzaei,Maryam Arsalanfar 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.1
The study addresses an enhanced approach for study of kinetics and mechanism of CO hydrogenation over Fe–Co catalyst. Kinetic models for rate of methane, paraffin and olefin formation have been developed by LHHW approach and information that obtained from UBI_QEP calculations.
Kinetic study of CO hydrogenation over co-precipitated iron–nickel catalyst
Ali A. Mirzaei,Rouhoullah M. Kiai,Hossein Atashi,Maryam Arsalanfar,Sara Shahriari 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
The kinetic of the Fischer–Tropsch synthesis over a Fe–Ni/Al2O3 catalyst was investigated in a fixed bed micro reactor. Experimental conditions were varied as follow: reaction pressure 2–10 bar, H2/CO feed ratio of 2/1 and space velocity of 96–450 cm3(STP)/h/gramcatalyst at the temperature range 523–573 K. On the basis of carbide-enol mechanism and Langmuir–Hinshelwood–Hougen–Watson (LHHW) type rate equations, seventeen kinetic expressions for CO consumption were tested and interaction between adsorption HCO and dissociated adsorption hydrogen as the controlling step gave the most plausible kinetic model. The activation energy was 46.5 kJ/mole for optimal kinetic model.
Modeling and operating conditions optimization of Fischer–Tropsch synthesis in a fixed-bed reactor
Ali Akbar Mirzaei,Bahman Shirzadi,Hossein Atashi,Mohsen Mansouri 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
The effect of a range of operation variables such as pressure, low temperature and H2/CO molar feed ration the catalytic performance of 80%Co/20%Ni/30 wt% La2O3/1 wt% Cs catalyst was investigated. It was found that the optimum operating conditions is a H2/CO = 2/1 molar feed ratio at 260 8C temperature and 2 bar pressure. Reaction rate equations were derived on the basis of the Langmuir–Hinshelwood–Hougen–Watson (LHHW) type models for the Fischer–Tropsch reactions. The activation energy obtained was 59.69 kJ/mol for optimal kinetic model.
Kinetics studies of nano-structured cobalt–manganese oxide catalysts in Fischer–Tropsch synthesis
Mohsen Mansouri,Hossein Atashi,Farshad Farshchi Tabrizi,Ali Akbar Mirzaei,Ghobad Mansouri 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4
The nano-structured cobalt/manganese oxide catalyst was prepared by thermal decomposition of [Co(NH3)4CO3]MnO4 precursor, and was tested for the Fischer–Tropsch reaction (hydrocarbon forming)in a fixed-bed micro-reactor. Experimental conditions were varied as follow: reaction pressure 1–10 bar,H2/CO feed ratio of 1–2 and space velocity of 3600 h1 at the temperature range of 463.15–523.15 K. On the basis of carbide and/or enolic mechanisms and Langmuir–Hinshelwood–Hougen–Watson (LHHW)type rate equations, 30 kinetic expressions for CO consumption were tested and interaction between adsorption HCO and dissociated adsorption hydrogen as the controlling step gave the most plausible kinetic model. The kinetic parameters were estimated with non-linear regression method and the activation energy was 80.63 kJ/mol for optimal kinetic model. Kinetic results indicated that in Fischer–Tropsch synthesis (FTS) rate expression, the rate constant (k) has been increased by decreasing the catalyst particle size. The catalyst characterization was carried out using different methods including powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurements.
Salman Khazaei,Jalal Poorolajal,Hossein Mahjub,Nader Esmailnasab,Mohammad Mirzaei 한국역학회 2012 Epidemiology and Health Vol.34 No.-
OBJECTIVES: The number of illicit drug users is prone to underestimation. This study aimed to use the capture-recapture method as a statistical procedure for measuring the prevalence of intravenous drug users (IDUs) by estimating the number of unknown IDUs not registered by any of the registry centers. METHODS: This study was conducted in Hamadan City, the west of Iran, in 2012. Three incomplete data sources of IDUs, with partial overlapping data, were assessed including: (a) Volunteer Counseling and Testing Centers(VCTCs); (b) Drop in Centers (DICs); and (c) Outreach Teams (ORTs). A log-linear model was applied for the analysis of three-sample capture-recapture results. Two information criteria were used for model selection including Akaike’s Information Criterion and the Bayesian Information Criterion. RESULTS: Out of 1,478 IDUs registered by three centers, 48% were identified by VCTCs, 32% by DICs, and 20% by ORTs. After exclusion of duplicates, 1,369 IDUs remained. According to our findings, there were 9,964 (95% CI, 6,088 to 17,636) IDUs not identified by any of the centers. Hence, the real number of IDUs is expected to be 11,333. Based on these findings, the overall completeness of the three data sources was around 12% (95% CI, 7% to 18%). CONCLUSION: There was a considerable number of IDUs not identified by any of the centers. Although the capture-recapture method is a useful and practical approach for estimating unknown populations, due to the assumptions and limitations of the method, the results must be interpreted with caution.
Amir Eshraghi,Ali Akbar Mirzaei,Rahbar Rahimi,Hossein Atashi 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.10
Mass transfer limitations and kinetics studies were performed for Fischer-Tropsch Synthesis over spherical 10 wt% Fe-10wt% Co-0.5 wt% Pt/79.5 wt% -Al2O3 catalyst in a fixed bed reactor. The external mass transfer limitation was checked by studying the effect of gas hourly space velocity (GHSV) and feed flow rate (at constant GHSV) on CO conversion. Theoretical and practical methods were applied to assess the effect of catalyst pellet size on the internal mass transfer limitation. The results indicated there is external diffusion limitation for GHSV lower than 4,200 h1. Both the theoretical and practical methods showed that the reaction is free of internal diffusion limitation with average particle sizes of 0.21 and 0.42 mm due to Thiele modulus smaller than 0.4, denoting that the rate of reaction is kinetically controlled. The kinetics results demonstrated the combined enol and carbide mechanism-based model was able to provide a good fit for the experimental data.
Sarrafzadeh, Farhad,Sohrevardi, Seyed Mojtaba,Abousaidi, Hamid,Mirzaei, Hossein The Korean Pediatric Society 2021 Clinical and Experimental Pediatrics (CEP) Vol.64 No.8
Background: Antibiotic resistance is associated with longer hospitalizations, higher treatment costs, and increased morbidity and mortality rates. Purpose: This study aimed to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in Iranian children. Methods: International databases, including Web of Science, PubMed, Embase, and Scopus, and Iranian databases, including Scientific Information Database (www.sid.ir), Magiran, and Iranian Database for Medical Literature (idml.research.ac.ir), were systematically searched for articles published between January 2000 and August 2019. Sources of heterogeneity were determined using subgroup analysis and meta-regression. Results: Overall, 343 studies were identified; of them, 20 were included in the meta-analysis to estimate the pooled prevalence. The pooled prevalence of MRSA was 42% (95% confidence interval [CI], 29-55) among culture-positive cases of S. aureus, 51% (95% CI, 39-62) in hospitalized children, and 14% (95% CI, 0.05-27) in healthy children. Conclusion: The overall pooled prevalence of MRSA in children was 42%. Appropriate infection control measures and effective antibiotic therapy are needed.
Rooki, Reza,Ardejani, Faramarz Doulati,Moradzadeh, Ali,Mirzaei, Hossein,Kelessidis, Vassilios,Maglione, Roberto,Norouzi, Mahmood 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.3
The rheological properties of a drilling fluid directly affect flow characteristics and hydraulic performance. Drilling fluids containing bentonite mixtures exhibit non-Newtonian rheological behavior which can be described with a high degree of accuracy by the three-parameter Herschel-Bulkley (HB) model. To determine the HB parameters, standard statistical techniques, such as the non-linear regression (NL) method are routinely used. However, sometimes they provide non physically acceptable solutions which could produce wrong values of the significant hydraulic parameters which affect drilling operations. To obtain more accurate results, the Golden Section (GS) method was subsequently developed by Kelessidis et al. (2006). In this work a different technique was developed using the Genetic Algorithms (GAs) to provide an easy-to-use tool in order to determine the three parameters of the Herschel-Bulkley model more accurately. To evaluate the accuracy of the GAs method, experimental viscometric data sets of drilling fluids were taken from the literature and the results were compared with the ones obtained by using the NL and GS techniques. The results show that the GAs and the GS methods provide similar results with very high correlation coefficients and small sum of square errors for most of the samples exhibiting negative yield stress values by the NL technique, while giving similar to the NL technique for the samples that were predicted with positive yield stress. However, in some cases, the GAs method gives better and more realistic results than the GS method.