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Effect of TiO2 loading on the morphology and CO2/CH4 separation performance of PEBAX-based membranes

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Frontiers of Chemical Science and Engineering 2019年第3期13卷 517-530页

作者： navid Azizi Mojgan Isanejad Toraj Mohammadi Reza M. Behbahani Research and Technology Center of Membrane Processes Chemical Engineering DepartmentIran University o f Science and Technology (IUST)NarmakTehranIran Gas Engineering Department Petroleum University of TechnologyAhwazIran

Membranes have attracted much attention as economical methods for industrial chemical processes. The effects of the titanium dioxide nanoparticle load on the morphology and CO2/CH4 separation performance of poly (ether-block-amide)(PEBAX-1657) mixed matrix membranes (MMMs) were investigated from pressures of 3-12 bar and temperatures of 30℃-60℃. The PEBAX membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and tensile strength analysis. The incorporation of TiO2 nanoparticles into the polymeric MMMs improved the CO2/CH4 gas separation performance (both the permeability and selectivity) of the membranes. The CO2 permeability and ideal CO2/CH4 selectivity values of the nanocomposite membrane loaded with 8 wt-% TiO2 were 172.32 Barrer and 24.79, respectively whereas those of the neat membrane were 129.87 Barrer and 21.39, respectively.

关键词： mixed matrix membrane TiO2 nanoparticles PEBAX-1657 C02/CH4 separation

Multi-scale analysis of flow structures in fluidized beds with immersed tubes

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Particuology 2015年第4期13卷 99-106页

作者： Hamid R.Norouzi Maryam Tahmasebpoor Reza Zarghami navid Mostoufi Multiphase Systems Research Lab.School of Chemical Engineering College of EngineeringUniversity of Tehran Department of Chemical and Petroleum Engineering University of Tabriz

Multi-scale analysis and non-linear analysis were combined to investigate the hydrodynamics of fluidized beds with and without horizontal tubes. Pressure fluctuations were measured and analyzed employing discrete wavelet analysis, recurrence plot analysis, and recurrence quantification analysis. A systematic procedure was followed to determine wavelet parameters. At low gas velocities, the energy of macro-structures reduces with the addition of the first tube and then increases with the addition of a second tube. However, there is no notable difference at high gas velocities. Determinism is high for the bed without tubes, which can be attributed to the periodic behavior of bubbles. Determinism decreases with the addition of tubes because the breakage of bubbles results in less periodic behavior. The three methods of analysis used in this study captured the effects of immersed tubes on the hydrodynamics of fluidized beds. Recurrence quantitative analysis was found to be a powerful and easy-to-use method that can capture the nonlinear characteristics of fluidized beds much more quickly than conventional methods of nonlinear analysis. This method can thus be effectively used for the online monitoring of hydrodynamic changes in fluidized beds.

关键词： Immersed tube Non-linear analysis Pressure fluctuations Recurrence plot Wavelet transform

Optimization of Sputtering Parameters for the Deposition of Low Resistivity Indium Tin Oxide Thin Films

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Acta Metallurgica Sinica(English Letters) 2014年第2期27卷 324-330页

作者： navid Yasrebi Behrang Bagheri Payam Yazdanfar Bizhan Rashidian Pezhman Sasanpour Department of Electrical Engineering Sharif University of Technology Department of Medical Physics and Biomedical Engineering Faculty of MedicineShahid Beheshti University of Medical Sciences

Indium tin oxide （ITO） thin films have been deposited using RF sputtering technique at different pressures, RF powers, and substrate temperatures. Variations in surface morphology, optical properties, and film resistances were measured and analyzed. It is shown that a very low value of sheet resistance （1.96 Ω/sq.） can be achieved with suitable arrangement of the deposition experiments. First, at constant RF power, deposition at different pressure values is done, and the condition for achieving minimum sheet resistance （26.43 Ω/sq.） is found. In the next step, different values of RF powers are tried, while keeping the pressure fixed on the previously found minimum point （1-2 Pa）. Finally, the minimum resistivity is obtained by sweeping the substrate temperatures, while keeping RF power and the working pressure at their optimum values. Furthermore, the effects of process parameters on properties, such as the surface morphology and the optical transmission, are discussed. Although the point of minimum resistivity does not coincide with that of the maximum transparency of ITO film, relatively acceptable values of transmittance （approximately 75% on a glass substrate with intrinsic transparency of 89%） can be obtained.

关键词： Indium tin oxide Sputtering Deposition Parameters optimization

Characterization of the bubbling fluidization of nanoparticles

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Particuology 2014年第5期12卷 75-83页

作者： Mohammad R.Tamadondar Reza Zarghami Maryam Tahmasebpoor navid Mostoufi Multiphase Systems Research Lab. Oil and Gas Processing Centre of ExcellenceSchool of Chemical EngineeringCollege of EngineeringUniversity of TehranP.O.Box 11155/4563Tehran.Iran

The dynamic features of an agglomerate bubbling fluidization of nanoparticles were investigated through the analysis of pressure fluctuations. Experiments were carried out in a lab-scale fluidized bed at ambient conditions using 10-15 nm silica nanoparticles without any surface modification. Pressure fluctuation signals were processed in both frequency and time-frequency domains to characterize the behavior of various scales of phenomena （i.e.. macro-, meso-, and micro-structures） during fluidization. Due to the aggregation of nanoparticles, three separate broad peaks were observed in the frequency spectra of the pressure signals measured in the bubbling fluidized bed of nanoparticles. A non-intrusive method based on the decoupling of pressure fluctuations recorded simultaneously in the plenum and in the bed was used to determine the approximate size of the bubbles in the bed.

关键词： Fluidization Hydrodynamics Pressure fluctuations Nanoparticles

Predictor homotopy analysis method for nanofluid flow through expanding or contracting gaps with permeable walls

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International Journal of Biomathematics 2015年第4期8卷 145-159页

作者： navid Freidoonimehr Behnam Rostami Mohammad Mehdi Rashidi Young Researchers and Elite Club Hamedan Branch Islamic Azad University Hamedan Iran Shanghai Key Lab of Vehicle Aerodynamics and Vehicle Thermal Management Systems4800 Cao An Rd. Jiadong Shanghai 201804 P. R. China ENN-Tongji Clean Energy Institute of Advanced Studies Shanghai P. R. China Mechanical Engineering DepartmentEngineering Faculty of Bu-Ali Sina University Hamedan Iran

In this paper a definitely new analytical technique, predictor homotopy analysis method （PHAM）, is employed to solve the problem of two-dimensional nanofluid flow through expanding or contracting gaps with permeable walls. Moreover, comparison of the PHAM results with numerical results obtained by the shooting method coupled with a Runge- Kutta integration method as well as previously published study results demonstrates high accuracy for this technique. The fluid in the channel is water containing different nanoparticles： silver, copper, copper oxide, titanium oxide, and aluminum oxide. The effects of the nanoparticle volume fraction, Reynolds number, wall expansion ratio, and different types of nanoparticles on the flow are discussed.

关键词： Nanofluid permeable walls porous channel non-dimensional wall dilationrate predictor homotopy analysis method.

Comparative CFD-DEM study of flow regimes in spout-fluid beds

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Particuology 2024年第2期85卷 323-334页

作者： Hamed Hoorijani Behrad Esgandari Reza Zarghami Rahmat Sotudeh-Gharebagh navid Mostoufi Multiphase Systems Research Lab School of Chemical EngineeringCollege of EngineeringUniversity of TehranP.O.Box 11155-4563TehranIran Department of Particulate Flow Modelling Johannes Kepler UniversityAltenbergerstr.694040LinzAustria

Spout-fluid beds are unique systems that require thorough study prior to their industrial *** this study,the hydrodynamics of spout-fluid beds were investigated using 3D computational fluid dy-namics coupled with discrete element method(CFD-DEM).Three flow regimes,including jet-in-fluidized bed,spouting-with-aeration,and intermediate/spout-fluidization were studied,and the particle mixing was quantified in these regimes using the Lacey mixing *** results showed that both axial and lateral mixing rates are better in jet-in-fluidized bed and the spouting-with-aeration flow regimes,with the axial mixing being superior to the lateral in all flow *** the diffusivity coefficient revealed that mixing in the jet-in-fluidized bed flow regime is better due to the formation and eruption of bubbles in the ***,the granular temperature was analyzed in all flow regimes,and higher particle velocity fluctuations were observed in the spouting-with-aeration and the jet-in-fluidized bed flow regimes due to the higher spout gas velocity and formation of bubbles in the *** study provides valuable insights into the hydrodynamics of spout-fluid beds in different flow regimes,which can aid in the design and optimization of spout-fluid bed reactors for various industrial applications.

关键词： Flow regime Mixing Diffusivity CFD-DEM Hydrodynamics Spout-fluid bed

Improved prediction of slope stability using a hybrid stacking ensemble method based on finite element analysis and field data

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第1期13卷 188-201页

作者： navid Kardani Annan Zhou Majidreza Nazem Shui-Long Shen Civil and Infrastructure Discipline School of EngineeringRoyal Melbourne Institute of Technology(RMIT)MelbourneVictoriaAustralia Department of Civil and Environmental Engineering College of EngineeringShantou UniversityShantou515063China

Slope failures lead to catastrophic consequences in numerous countries and thus the stability assessment for slopes is of high interest in geotechnical and geological engineering researches.A hybrid stacking ensemble approach is proposed in this study for enhancing the prediction of slope *** the hybrid stacking ensemble approach,we used an artificial bee colony(ABC)algorithm to find out the best combination of base classifiers(level 0)and determined a suitable meta-classifier(level 1)from a pool of 11 individual optimized machine learning(OML)*** element analysis(FEA)was conducted in order to form the synthetic database for the training stage(150 cases)of the proposed model while 107 real field slope cases were used for the testing *** results by the hybrid stacking ensemble approach were then compared with that obtained by the 11 individual OML methods using confusion matrix,F1-score,and area under the curve,*** comparisons showed that a significant improvement in the prediction ability of slope stability has been achieved by the hybrid stacking ensemble(AUC?90.4%),which is 7%higher than the best of the 11 individual OML methods(AUC?82.9%).Then,a further comparison was undertaken between the hybrid stacking ensemble method and basic ensemble classifier on slope stability *** results showed a prominent performance of the hybrid stacking ensemble method over the basic ensemble ***,the importance of the variables for slope stability was studied using linear vector quantization(LVQ)method.

关键词： Slope stability Machine learning(ML) Stacking ensemble Variable importance Artificial bee colony(ABC)

An efficient correlation for calculating compressibility factor of natural gases

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Journal of Natural Gas Chemistry 2010年第6期19卷 642-645页

作者： navid Azizi Dr.R.Behbahani Dr.M.A.Isazadeh Gas Engineering Department Petroleum University of Technology

Compressibility factor （z-factor） values of natural gases are necessary in most petroleum engineering *** arises when there are few available experimental data for the required composition,pressure and temperature *** of the most common methods of calculating z-factor values is empirical ***,a new correlation based on the famous Standing-Katz （S-K） Chart is presented to predict z-factor *** advantage of this correlation is that it is explicit in z and thus does not require an iterative solution as is required by other ***,the comparison between new one and other correlations is carried out and the results indicate the superiority of the new correlation over the other correlations used to calculate z-factor.

关键词： natural gas compressibility factor explicit correlation

Water Net: An adaptive matching pipeline for segmenting water with volatile appearance

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Computational Visual Media 2020年第1期6卷 65-78页

作者： Yongqing Liang navid Jafari Xing Luo Qin Chen Yanpeng Cao Xin Li School of Electrical Engineering and Computer Science Louisiana State UniversityUSA Department of Civil Engineering Louisiana State UniversityUSA Department of Mechanical Engineering Zhejiang UniversityChina Department of Civil Engineering Northeastern UniversityUSA.E-mail:q.chen@northeastern.edu

We develop a novel network to segment water with significant appearance variation in *** existing state-of-the-art video segmentation approaches that use a pre-trained feature recognition network and several previous frames to guide segmentation,we accommodate the object’s appearance variation by considering features observed from the current *** dealing with segmentation of objects such as water,whose appearance is non-uniform and changing dynamically,our pipeline can produce more reliable and accurate segmentation results than existing algorithms.

关键词： video segmentation water segmentation appearance adaptation