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- 검색키워드
- 저자 : Afkar, Hossein (검색결과 4 건)
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Assessing the ductility of moment frames utilizing genetic algorithm and artificial neural networks
Mazloom, Moosa,Afkar, Hossein,Pourhaji, Pardis Techno-Press 2018 Structural monitoring and maintenance Vol.5 No.4
The aim of this research is to evaluate the effects of the number of spans, height of spans, number of floors, height of floors, column to beam moment of inertia ratio, and plastic joints distance of beams from columns on the ductility of moment frames. For the facility in controlling the ductility of the frames, this paper offers a simple relation instead of complex equations of different codes. For this purpose, 500 analyzed and designed frames were randomly selected, and their ductility was calculated by the use of nonlinear static analysis. The results cleared that the column-to-beam moment of inertia ratio had the highest effect on ductility, and if this relation was more than 2.8, there would be no need for using the complex relations of codes for controlling the ductility of frames. Finally, the ductility of the most frames of this research could be estimated by using the combination of genetic algorithm and artificial neural networks properly.
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Bita Hosseinian Ahangarnazha,Masoud Pourbaba,Amir Afkar 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.4
In this paper, the influence of adding multi-walled carbon nanotube (MWCNT) on the pull behavior of steel and GFRP bars in ultra-high-performance concrete (UHPC) was examined experimentally and numerically. For numerical analysis, 3D nonlinear finite element modeling (FEM) with the help of ABAQUS software was used. Mechanical properties of the specimens, including Young's modulus, tensile strength and compressive strength, were extracted from the experimental results of the tests performed on standard cube specimens and for different values of weight percent of MWCNTs. In order to consider more realistic assumptions, the bond between concrete and bar was simulated using adhesive surfaces and Cohesive Zone Model (CZM), whose parameters were obtained by calibrating the results of the finite element model with the experimental results of pullout tests. The accuracy of the results of the finite element model was proved with conducting the pullout experimental test which showed high accuracy of the proposed model. Then, the effect of different parameters such as the material of bar, the diameter of the bar, as well as the weight percent of MWCNT on the bond behavior of bar and UHPC were studied. The results suggest that modifying UHPC with MWCNT improves bond strength between concrete and bar. In MWCNT per 0.01 and 0.3 wt% of MWCNT, the maximum pullout strength of steel bar with a diameter of 16 mm increased by 52.5% and 58.7% compared to the control specimen (UHPC without nanoparticle). Also, this increase in GFRP bars with a diameter of 16 mm was 34.3% and 45%.
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Pros and cons of the health transformation program in Iran:
Enayatollah Homaie Rad,Vahid Yazdi-Feyzabadi,Shahrokh Yousefzadeh-Chabok,Abolhasan Afkar,Ahmad Naghibzadeh 한국역학회 2017 Epidemiology and Health Vol.39 No.-
OBJECTIVES: The health transformation program was a recent reform in the health system of Iran that was implemented in early 2014. Some of the program’s important goals were to improve the equity of payments and to reduce out-of-pocket (OOP) payments and catastrophic health expenditures (CHE). In this study, these goals were evaluated using a before-and-after analysis. METHODS: Data on household income and expenditures in Guilan Province were gathered for the years 2013 and 2015. OOP payments for outpatient, inpatient, and drug services were calculated, and the results were compared using the propensity score matching technique after adjusting for confounding variables. Concentration indices and curves were added to quantify changes in inequity before and after the reform. The incidence of catastrophic expenditures was then calculated. RESULTS: Overall and outpatient service OOP payments increased by approximately 10 dollars, while for other types of services, no significant changes were found. Inequity and utilization of services did not change after the reform. However, a significant reduction was observed in CHE incidence (5.75 to 3.82%). CONCLUSIONS: The reform was successful in decreasing the incidence of CHE, but not in reducing the monetary amount of OOP payments or affecting the frequency of health service utilization.
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Enayatollah Homaie Rad,Sajad Delavari,Afsoon Aeenparast,Abolhassan Afkar,Faranak Farzadi,Farzaneh Maftoon 대한가정의학회 2017 Korean Journal of Family Medicine Vol.38 No.5
Background: The main aim of this study was to evaluate the achievements of some important goals of Iran’s urban family physician plan. This plan was implemented when the country experienced economic instability. We exam-ine whether an economic crisis affects the efficacy of a healthcare program.Methods: We used the household income and expenditures survey data for 2011 (before program implementa-tion) and 2012 (after program implementation). Changes in out-of-pocket payments and healthcare utilization were investigated using the propensity score matching estimator. Furthermore, changes in inequality in these two dimensions were examined.Results: No changes in out-of-pocket payments and healthcare utilization were found after the implementation of this program; however, inequality in out-of-pocket payments increased during the reform.Conclusion: The urban family physician program was not implemented completely and many of its fundamental settings were not conducted because of lack of necessary healthcare infrastructure and budget limitations. Family physician programs should be implemented under a strong healthcare infrastructure and favorable economic con-ditions.
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