Wyniki wyszukiwania - BazTech

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Synthesis, microstructure and mechanical properties of bronze–molybdenum composites processed via LPS and SPS methods

Memari S., Ardestani M., Abbasi A.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 4

1013--1023

EN

In this work, synthesis, densification and properties of bronze–70 wt% Mo and bronze–30 wt% Mo composite powders were investigated. The composite powders were prepared by mechanical milling of bronze–Mo powder mixtures for 16 h. The results of cold compressibility investigations showed that Heckel and Ge equations provided the best fit scenario for bronze–70 wt% Mo and bronze–30 wt% Mo, respectively. The composite powders were consolidated via pressureless and spark plasma sintering processes. The relative densities of spark plasma sintered samples with 30 and 70 wt% molybdenum were about 98%. However, the relative density of bronze–70 wt% Mo and bronze–30 wt% Mo pressureless sintered samples were 97.1 and 94.3%, respectively. The scanning electron microscopy observations revealed that the size and dispersion of Mo particles within the bronze matrix in the pressureless sintered samples was completely different from that of the spark plasma sintered ones. Furthermore, it was found that in spite of nearly close relative densities, the hardness and flexural strength of the spark plasma sintered samples were higher than that of the pressureless sintered ones which was due to different shape, size and dispersion of the Mo particles within the matrix phase in the different samples. According to the results, the preferred densification process was SPS method.

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Influence of nozzle hole diameter on the first and second law balance in a DI Diesel engine

Abbasi A., Emamverdi O.

Journal of Power Technologies

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2014

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Vol. 94, nr 1

20--33

EN

In the present work, influence of nozzle holes diameter is studied on the first and second law balance in DI Diesel engine. To this aim, the first law analysis is done by using the results of a three dimensional CFD model. The results show a good agreement with the experimental data. Also for the second law analysis, a developed in house computational code is applied. Behaviors of the results have a good accordance with the literature. The results show that increase in nozzle holes diameter increases both indicated work and heat loss to walls. Also about the second law terms, results declare that increase in nozzle holes diameter leads to increase in indicated work availability, heat loss availability, and entropy generation per cycle and decrease in combustion irreversibility and exhaust gas availability.

3

Segmentation and edge detection based on modified ant colony optimization for iris image processing

Biniaz A., Abbasi A.

Journal of Artificial Intelligence and Soft Computing Research

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2013

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Vol. 3, No. 2

133--141

EN

Ant colony optimization (stocktickerACO) is a meta-heuristic algorithm inspired by food searching behavior of real ants. Recently stocktickerACO has been widely used in digital image processing. When artificial ants move in a discrete habitat like an image, they deposit pheromone in their prior position. Simultaneously, vaporizing of pheromone in each iteration step avoids from falling in the local minima trap. Iris recognition because of its great dependability and non-invasion has various applications. simulation results demonstrate stocktickerACO algorithm can effectively extract the iris texture. Also it is not sensitive to nuisance factors. Moreover, stocktickerACO in this research preserves details of the various synthetic and real images. Performance of ACO in iris segmentation is compared with operation of traditional approaches such as canny, robert, and sobel edge detections. Experimental results reveal high quality and quite promising of stocktickerACO to segment images with irregular and complex structures.

4

Fast FCM with spatial neighborhood information for brain MR image segmentation

Biniaz A., Abbasi A.

Journal of Artificial Intelligence and Soft Computing Research

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2013

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Vol. 3, No. 1

15--25

EN

Among different segmentation approaches Fuzzy c-Means clustering (FCM) is a welldeveloped algorithm for medical image segmentation. In emergency medical applications quick convergence of FCM is necessary. On the other hand spatial information is seldom exploited in standard FCM; therefore nuisance factors can simply affect it and cause misclassification. This paper aims to introduce a Fast FCM (FFCM) technique by incorporation of spatial neighborhood information which is exploited by a linear function on fuzzy membership. Applying proposed spatial Fast FCM (sFFCM), elapsed time is decreased and neighborhood spatial information is exploited in FFCM. Moreover, iteration numbers by proposed FFCM/sFFCM techniques are decreased efficiently. The FCM/FFCM techniques are examined on both simulated and real MR images. Furthermore, to considerably decrease of convergence time and iterations number, cluster centroids are initialized by an algorithm. Accuracy of the new approach is same as standard FCM. The quantitative assessments of presented FCM/FFCM techniques are evaluated by conventional validity functions. Experimental results demonstrate that sFFCM techniques efficiently handle noise interference and significantly decrease elapsed time.

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Fast and easy preparation of a novel highly acidic sulfonic-functionalized SBA-1 cubic mesoporous catalyst and its application in the esterification of palmitic acid

Abbasi A., Mahjoub A. R., Badiei A. R.

Materials Science Poland

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2010

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Vol. 28, No. 3

617--624

EN

Propylsulfonic acid-functionalized cubic mesoporous silica was prepared through in situ oxidization of mercaptopropyl groups with H2O2 during co-condensation of tetraethyl orthosilicate and 3-mercaptopropyl trimethoxysilane under strong acidic conditions. The materials obtained with 5-20 mol % loadings of sulfonic acid groups had surface areas of up to 1300 m2/g and pore sizes of around 2.5 nm. Next, the catalytic activity of this material was investigated in esterification of palmitic acid as a compound model in the process of biodiesel production. Methyl ester production by this new nanoporous catalyst shows a very remarkable yield during a mild liquid phase reaction.

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A novel highly acidic sulfonic functionalized SBA-1 cubic mesoporous catalyst and its application in the esterification of palmitic acid

Abbasi A., Reza Mahjoub A., Badiei A. R.

Materials Science Poland

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2010

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Vol. 28, No. 2

565--572

EN

Propylsulfonic acid functionalized cubic mesoporous silica was fabricated through in situ oxidization of mercaptopropyl groups with H2O2 during co-condensation of tetraethyl orthosilicate and 3-mercaptopropyl trimethoxysilane under strong acidic conditions. The materials obtained with 5-20 mol % loadings of sulfonic acid groups had surface areas of up to 1300 m2/g and pore sizes of ca. 2.5 nm. The catalytic activity of this material was investigated: tests were performed on the esterification of palmitic acid being a model compound in the process of biodiesel production. Methyl ester yield on this new nanoporous catalyst is very remarkable during a mild liquid phase reaction.