http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Mehdi Bahrami,Javad karimi Sabet,Ali Hatamnejad,Abolfazl Dastbaz,Mohammad Ali Moosavian 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.11
RSM methodology was applied to present mathematical models for the fabrication of polyvinylidene fluoride (PVDF) dual-layer hollow fibers in membrane distillation process. The design of experiments was used to investigate three main parameters in terms of polymer concentration in both outer and inner layers and the flow rate of dope solutions by the Box-Behnken method. According to obtained results, the optimization was done to present the proper membrane with desirable properties. The characteristics of the optimized membrane (named HF-O) suggested by the Box-Behnken (at the predicted point) showed that the proposed models are strongly valid. Then, a morphology study was done to modify the fiber by a combination of three types of a structure such as macro-void, sponge-like and sharp finger-like. It also improved the hydrophobicity of outer surface from 87 to 113o and the mean pore size of the inner surface from 108.12 to 560.14nm. The DCMD flux of modified fiber (named HF-M) enhanced 62% more than HF-O when it was fabricated by considering both of RSM and morphology study results. Finally, HF-M was conducted for long-term desalination process up to 100hr and showed stable flux and wetting resistance during the test. These stepwise approaches are proposed to easily predict the main properties of PVDF dual-layer hollow fibers by valid models and to effectively modify its structure.
Kinetic modeling formulation of the methanol to olefin process: Parameter estimation
Mehdi Sedighi,Hussein Bahrami,Jafar Towfighi 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
Detailed kinetic models at the elementary step level were developed for the methanol to olefins (MTO) process over SAPO-34 catalyst. Starting from believable mechanisms, forming primary products was modeled rigorously by the Hougen–Watson formalism. Discrimination of kinetic equations and calculation of the parameters of best fit were performed by solving the mass conservation equations of the main products of the kinetic scheme. For rate constants, preexponential factors and apparent activation energies were then calculated according to the Arrhenius equation. For thermodynamic constants, the difference between apparent activation energies of forward and reverse reaction was considered. The kinetic model fits well the experimental data, which is obtained in a fixed bed reactor. The results showed that rising space-time is favorable for olefin yields while an optimum temperature might produce the maximum olefin.
Mohammad Amin Bahrami,Mohammad Mehdi Kiani,Raziye Montazeralfaraj,Hossein Fallah Zadeh,Morteza Mohammad Zadeh 질병관리본부 2016 Osong Public Health and Research Persptectives Vol.7 No.3
Objectives: Organizational learning is defined as creating, absorbing, retaining, transferring, and application of knowledge within an organization. This article aims to examine the mediating role of organizational learning in the relationship of organizational intelligence and organizational agility. Methods: This analytical and cross-sectional study was conducted in 2015 at four teaching hospitals of Yazd city, Iran. A total of 370 administrative and medical staff contributed to the study. We used stratified-random method for sampling. Required data were gathered using three valid questionnaires including Alberkht (2003) organizational intelligence, Neefe (2001) organizational learning, and Sharifi and Zhang (1999) organizational agility questionnaires. Data analysis was done through R and SPSS 18 statistical software. Results: The results showed that organizational learning acts as a mediator in the relationship of organizational intelligence and organizational agility (path coefficient = 0.943). Also, organizational learning has a statistical relationship with organizational agility (path coefficient = 0.382). Conclusion: Our findings suggest that the improvement of organizational learning abilities can affect an organization’s agility which is crucial for its survival.
Harmonics Elimination in a Multilevel Inverter with Unequal DC Sources Using a Genetic Algorithm
Iranaq, Ali Reza Marami,Kouhshahi, Mojtaba Bahrami,Kouhshahi, Mehdi Bahrami,Sharifian, Mohammad Bagher Bannae,Sabahi, Mehran Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.1
In this paper, an optimal solution to the harmonic reduction problem in a cascaded multilevel inverter with non-equal DC sources using a genetic algorithm (GA) is presented. Switching angles are generated for different values of modulation index by the proposed algorithm, considering minimum voltage total harmonic distortion (THD) whereas selected harmonics are controlled within the allowable limits at all desired modulation indices including the point of discontinuity. Results are stored as a look-up table to be used to control the inverter for a certain operating point. The computed angles are used in a simulated circuit in Matlab\Simulink to validate the results.