Wyniki wyszukiwania - Biblioteka Nauki

1

Multiple spike stall cells in low speed axial compressor rotor blade row

100%

Taghavi-Zenouz R. , Abbasi S.

Journal of Theoretical and Applied Mechanics

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2015

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tom Vol. 53 nr 1

47--57

EN

Inception and development of multiple stall cells of short length scales are numerically investigated in an axial compressor rotor blade row. The method of investigation is based on time accurate three-dimensional full annulus simulations. Time dependent flow structure results revealed that there are two criteria responsible for inception of a special kind of stall, introduced as spike stall in the literature. These criteria are defined as leading edge spillage and trailing edge backflow, which occur at specific mass flow rates near to stall conditions. The numerical results revealed that once the spike stall cells appear, they cover roughly two blade passages in the circumferential direction and cover about 25% of the blade height. By further revolution of the blade row, the number of cells tends to increase. For the present case study, the number of stall cells increased to three after 8.5 rotor revolutions from the moment of the initial spike stall occurrence. Even at this moment, both of the above mentioned criteria for the spike stall inception have been observed within the blades passages. These events caused the inlet relative flow angle to the blade rows, and therefore the flow incidence angle and consequent blockage to the main flow, to increase. The tip leakage flow frequency spectrum has been studied through surveying instantaneous static pressure signals imposed on pressure side of the blades and also on the casing walls. These latter results showed that any further revolving of the rotor blade row, exceeding 8.5 revolutions, causes the spike stall to disturb the flow structure significantly.

2

Preservation properties of stochastic orders by transformation to Harris family

100%

Abbasi S. , Alamatsaz M. H.

Probability and Mathematical Statistics

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2018

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tom Vol. 38, Fasc. 2

441--458

EN

Stochastic comparisons of lifetime characteristics of reliability systems and their components are of common use in lifetime analysis. In this paper, using Harris family distributions, we compare lifetimes of two series systems with random number of components, with respect to several types of stochastic orders. Our results happen to enfold several previous findings in this connection. We shall also show that several stochastic orders and ageing characteristics, such as IHRA, DHRA, NBU, and NWU, are inherited by transformation to Harris family. Finally, some refinements are made concerning related existing results in the literature.

3

Induced systemic resistance to wheat take-all disease by probiotic bacteria

80%

Jasem A. M. , Sharifi R. , Abbasi S.

Journal of Plant Protection Research

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2018

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tom 58

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nr 3

EN

In this study, the effect of six commercial biocontrol strains, Bacillus pumilus INR7, B. megaterium P2, B. subtilis GB03, B. subtilis S, B. subtilis AS and B. subtilis BS and four indigenous strains Achromobacter sp. B124, Pseudomonas geniculate B19, Serratia marcescens B29 and B. simplex B21 and two plant defense inducers, methyl salicylate (Me-SA) and methyl jasmonate (Me-JA) were assessed on suppression of wheat take-all disease. Treatments were applied either as soil drench or sprayed on shoots. In the soil drench method, the highest disease suppression was achieved in treatment with strains INR7, GB03, B19 and AS along with two chemical inducers. Bacillus subtilis S, as the worst treatment, suppressed take-all severity up to 56%. Both chemical inducers and bacterial strains AS and P2 exhibited the highest effect on suppression of take-all disease in the shoot spray method. Bacillus subtilis S suppressed the disease severity up to 49% and was again the worst strain. The efficacy of strains GB03 and B19 decreased significantly in the shoot spray method compared to the soil drench application method. Our results showed that most treatments had the same effect on take-all disease when they were applied as soil drench or sprayed on aerial parts. This means that induction of plant defense was the main mechanism in suppressing take-all disease by the given rhizobacteria. It also revealed that plant growth was reduced when it was treated with chemical inducers. In contrast, rhizobacteria not only suppressed the disease, but also increased plant growth.

4

Investigation of inlet distortion effects on axial compressor performance based on streamline curvature method

80%

Abbasi S. , Pirnia A. , Taghavi-Zenouz R.

Journal of Theoretical and Applied Mechanics

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2018

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tom Vol. 56 nr 4

1005--1015

EN

In this paper, the effects of inlet flow distortion on performance maps and details of the flow field are investigated using the Streamline Curvature Method. The results are presented for both design and off-design conditions and compared with experimental data, which shows good agreement. The effects of inlet flow distortion are investigated by inlet total pressure variation in three different cases in the way that the average total pressure remains constant and equal to the design value. The results show that a relative increase in the total pressure at tip causes an increase in the pressure ratio and efficiency as well as a better performance in the choking region. Alternatively, a relative increase in the total pressure in hub causes opposite behavior and a better performance at the surging region.

5

Effects of the age of grafted larvae and the effects of supplemental feeding on some morphological characteristics of Iranian queen honey bees (Apis mellifera meda Skorikov, 1929)

80%

Mahbobi A. , Farshineh-Adl M. , Woyke J. , Abbasi S.

Journal of Apicultural Science

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2012

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tom 56

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nr 1

6

A semi-analytical solution on static analysis of circular plate exposed to non-uniform axisymmetric transverse loading resting on Winkler elastic foundation

80%

Abbasi S. , Farhatnia F. , Jazi S. R.

Archives of Civil and Mechanical Engineering

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2014

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tom Vol. 14, no. 3

476--488

EN

This paper is concerned with static analysis of functionally graded (FG) circular plates resting on Winkler elastic foundation. The material properties vary across the thickness direction so the power-law distribution is used to describe the constituent components. The differential transforms method (DTM) is utilized to solve the governing differential equations of bending of the thin circular plate under various boundary conditions. By employing this solution method, governing differential equations are transformed into recurrence relations and boundary/regularity conditions are changed into algebraic equations. In this study, the plate is subjected to uniform/non-uniform transverse load in two cases of boundary conditions (clamped and simply-supported). Some numerical examples are presented to show the influence of functionally graded variation, different elastic foundation modulus, and variation of the symmetrical transverse loads on the stress and displacement fields. Based on the results, the obtained out-plane displacement coincide with the available solution for a homogenous circular plate. It can be concluded that the applied method provides accurate results and it is easily used for static analysis of circular plates on an elastic foundation.

7

The effects of age of grafted larvae and of supplemental feeding on performance of Iranian honey bee colonies (Apis Mellifera Meda)

70%

Mahbobi A. , Woyke J. , Abbasi S. , Farshine-Adl M. , Malakzadegan A.

Journal of Apicultural Science

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2014

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tom 58

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nr 1

8

Two new species of Megaselia Rondani (Diptera, Phoridae) reared from fungi in Iran

70%

Disney R. H. L. , Barzegar S. , Zamani A. A. , Abbasi S. , Shoushtari R. V.

Fragmenta Faunistica

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2012

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tom 55

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nr 1

9

Characterization of probiotic abilities of lactobacilli isolated from iranian koozeh traditional cheese

70%

Tavakoli M. , Hamidi-Esfahani Z. , Hejazi M. A. , Azizi M. H. , Abbasi S.

Polish Journal of Food and Nutrition Sciences

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2017

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tom 67

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nr 1

EN

Eight lactic isolates including Lactobacillus plantarum (MT.ZH193, MT.ZH293, MT.ZH393 and MT.ZH593), L. casei (MT.ZH493), L. pentosus (MT.ZH693), and L. fermentum (MT.ZH893 and MT.ZH993) were identifi ed from an Iranian traditional cheese “Koozeh Paneer” using the morphological, phenotypical, biochemical and molecular characterization and then their probiotic characteristics were compared. Results showed that the lactic isolates of L. plantarum (MT.ZH293) and L. fermentum (MT.ZH893 and MT.ZH993) were resistant to all the used bile salts up to concentrations of 0.3 to 2.0%. All the strains showed low sensitivity to the presence of conjugated bile salts. L. plantarum MT.ZH293 exhibited the highest enzymatic activity of β-galactosidase and survival rate in a simulated stomach duodenum passage. L. casei MT.ZH493 generated the highest amount of hydrogen peroxide, followed by L. fermentum MT.ZH993 and L. plantarum MT.ZH593. Although the most selected LAB isolates had a moderate cell surface hydrophobicity, L. plantarum MT. ZH593 expressed the highest cell surface hydrophobicity. L. fermentum MT.ZH893 had strong resistance to all the antibiotics tested such as amoxicillin, ceftriaxon, chloramphenicol, erythromycin, gentamycin, streptomycin, tetracycline and vancomycin. Five lactic strains of L. plantarum (MT.ZH193, MT.ZH393 and MT.ZH593) and L. fermentum (MT.ZH893 and MT.ZH993) inhibited the growth of the tested foodborne pathogens including Escherichia coli PTCC5052, Salmonella enterica, Enetrococcus hirea, Staphylococcus aureus and Pseudomonas aeruginosa.

10

A new species of silverside from the Late Miocene of NW Iran

70%

Carnevale G. , Haghfarshi E. , Abbasi S. , Alimohammadian H. , Reichenbacher B.

Acta Palaeontologica Polonica

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2011

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tom 56

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nr 4

EN

The genus Atherina (Atheriniformes, Teleostei) includes five extant brackish and marine species that inhabit the eastern Atlantic, Mediterranean Sea, Black Sea, and Caspian Sea. Several fossil species are known from the Mediterranean and Paratethyan basins. Here we describe a new fossil species, Atherina atropatiensis sp. nov., from Upper Miocene deposits of the intramontane Tabriz Basin in NW Iran, based on well−preserved, articulated skeletons from the Lignite Beds at Baghmisheh−Marzdaran, near Tabriz. The new fossil species closely resembles the Recent A. boyeri, the only extant species of Atherina in the Caspian Sea, from which it can be distinguished by the different relative development of the ascending and alveolar processes of the premaxilla, and the mutual relationship between pleural ribs and dorsolateral process of the basipterygium. The systematic and zoogeographic affinities of A. atropatiensis indicate that the Lignite Beds of the Tabriz Basin were deposited in a euryhaline environment and that a connection between the intramontane Tabriz Basin and the Eastern Paratethys (Southern Caspian Sea) once existed.