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Wu X.,New Mexico State University | Niknam Shahrak M.,New Mexico State University | Niknam Shahrak M.,Quchan University of Advanced Technologies | Yuan B.,New Mexico State University | And 2 more authors.
Microporous and Mesoporous Materials

There are surging demands to separate carbon dioxide from methane in upgrading low-quality natural gas including biogas with an energy efficient process. In this work, adsorption equilibria and kinetics of CO2 and CH4 on a zeolitic imidazolate framework ZIF-7 were determined at various temperatures and gas pressures up to 1 bar, to evaluate the feasibility of removing CO2 from CH4 in a vacuum swing adsorption process using ZIF-7 as adsorbent. The as-synthesized ZIF-7 sample was characterized with scanning electron microscopy for crystal structure, powder X-ray diffraction for phase structure, thermal gravimetric analysis for thermal stability, and carbon dioxide adsorption at 0 C for pore textural properties. To study the gate-opening of ZIF-7, CO2 adsorption was measured at five different temperatures (273, 298, 323, 348 and 373 K) and pressures up to 10 bar. A thermodynamic model was employed to estimate the free energy of phase transition between narrow pore and large pore, and a modified dual-site Sips equation could fit the S shape CO2 isotherms well. Adsorption equilibrium selectivity (α) and adsorbent selection parameter for pressure swing adsorption processes (S) were calculated from the adsorption equilibrium data. The relatively high values of adsorption selectivities suggest that ZIF-7 is a promising adsorbent candidate for CO2/CH4 separation in a pressure swing adsorption process. © 2014 Elsevier Inc. All rights reserved. Source

Hadizadeh H.,Quchan University of Advanced Technologies
Proceedings of the International Symposium on Artificial Intelligence and Signal Processing, AISP 2015

This paper presents a rotation-invariant texture descriptor, which is robust to noise. In the proposed method, a given gray-scale texture image is first filtered by a set of Gabor wavelets filters. The filters are designed such that their half-peak magnitude support in the frequency spectrum touch each other with no overlap to reduce redundant information. After that a number of local binary patterns called 'Local Gabor Wavelets Binary Patterns' (LGWBPs) are computed based on the obtained Gabor wavelets filters responses via global measures. The histogram of the computed LGWBPs is then used as a texture feature vector. Extensive experiments were conducted on the well-known Outex, and CUReT databases in the presence of different levels of Gaussion noise. Experimental results indicate that the proposed method can be utilized as a suitable noise-robust and rotation-invariant texture descriptor for texture classification. © 2015 IEEE. Source

Pour M.,Quchan University of Advanced Technologies | Torabizadeh M.A.,University of Applied Science and Technology of Iran
Journal of Intelligent Manufacturing

In this paper, a new method is presented for prediction of cutting forces, surface texture and stability lobes in end milling operation based on time series analysis. In the approach, an equivalent damping ratio is defined for the cutting zone while the damping ratio of non-cutting zone is determined by experimental modal analysis. Using correlation dimension criterion, the simulation and experimental force signals are compared to anticipate the value of process damping by assessing the variation of correlation dimension for both signals. The effect of cutter deflections and run out are taken into account. Moreover, the stability lobes are predicted by considering the variation of process damping with cutting conditions. The feasibility of the proposed algorithm is verified experimentally for machining of Aluminum 7075-T6. Comparison of experiment results against simulation results indicates that the improved model can accurately predict cutting forces, surface texture and stability lobes for low radial immersion. © 2014 Springer Science+Business Media New York. Source

Farhadinia B.,Quchan University of Advanced Technologies
Information Sciences

This paper presents a series of score functions for hesitant fuzzy sets (HFSs) which provides us with a variety of new methods for ranking HFSs. The idea behind the methods is based on the score function for hesitant fuzzy elements (HFEs) that appears to be a subject worthy of further investigations in depth. The prominent characteristic of the HFS score-based method is that it can determine the priorities of the alternatives directly from the HFS score values. In a broad discussion, we describe a scheme for choosing an appropriate option from a set of HFS score-based methods according to what is expected from the score function and what is the nature of the values to be scored. Finally, the application of HFS ranking methods to multi-attribute decision making problems with hesitant fuzzy information is explained. © 2014 Elsevier Inc. All rights reserved. Source

Saei Moghaddam M.,Quchan University of Advanced Technologies | Zarringhalam Moghaddam A.,University of Tehran
Chemical Engineering Research and Design

In present work the effects of nitromethane (NM) and nitroethane (NE) as nitrogenated additives on physical properties, combustion performance, and emission of diesel fuel, were studied. Nitrogenated additives have high oxygen content and are considered as oxygenated additives. These additives were blended with diesel fuel, in 1/9 volume ratio. The experimental study was carried out on ECE R-96 8-modes cycle. The result showed that the use of additives reduces viscosity but increases cetane index. In addition, nitrogenated additives increased brake thermal efficiency (BTE) while reduced certain exhaust emissions. Results of AVL SPC 472_MCE97 analysis showed that the addition of NE can reduce the overall smoke value by 44%. The smoke emission decreased at the maximum torque speed (1500. rpm) rather than at the rated power speed (2200. rpm). © 2014 The Institution of Chemical Engineers. Source

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