Autor: Najafi, M. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Implications of inertia for hydroelastic instability of Herschel-Bulkley fluids in plane poiseuille flow
Autorzy:: Jafargholinejad, S.
Najafi, M.
Powiązania:: https://bibliotekanauki.pl/articles/280168.pdf
Data publikacji:: 2018
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: inertia
instability
Herschel-Bulkley fluid
Mooney-Rivlin solid
Opis:: This study investigates the effects of inertia on the hydroelastic instability of a pressure- -driven Herschel-Bulkley fluid passing through a two-dimensional channel lined with a polymeric coating. The no-viscous hyperelastic polymeric coating is assumed to follow the two-constant Mooney-Rivlin model. In this work, analytical basic solutions are determined for both the polymeric gel and the fluid at very low Reynolds numbers. Next, the basic solutions are subjected to infinitesimally-small, normal-mode perturbations. After eliminating the nonlinear terms, two 4-th order differential equations are obtained. The equations with appropriate boundary conditions are then numerically solved using the shooting method. The results of the solution show that the inertia terms in the perturbed equations destabilize the pressure-driven Herschel-Bulkley fluid flow. The investigation reveals that the elastic parameter has a stabilizing effect on the flow. Also, based on the obtained results, the yield stress, depending on the power-law index, has a stabilizing or destabilizing effect on the flow. Since in this work the inertia terms are included in the pertinent governing equations, therefore, the results of this study are much more realistic and reliable than previous works in which inertia terms were absent. In addition, unlike the previous works, the present study considers both the shear-thinning and shear-thickening types of fluids. Hence, the results of this work embrace all the fluids which obey the Herschel-Bulkley model.
Źródło:: Journal of Theoretical and Applied Mechanics; 2018, 56, 4; 1205-1216
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 2.

Tytuł:: Inclination angle implications for fluid flow and mixed convection in complex geometry enclosure-meshless numerical analyses
Autorzy:: Najafi, M.
Nikfar, M.
Arefmanesh, A.
Powiązania:: https://bibliotekanauki.pl/articles/279898.pdf
Data publikacji:: 2015
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: meshless
Petrov-Galerkin
mixed convection
rectangular cavity
wavy wall
Opis:: The meshless local Petrov-Galerkin (MLPG) method is extended to analyze the mixed convection and fluid flow in an inclined two-dimensional lid-driven cavity. The enclosure considered comprises two insulated vertical walls and a wavy bottom wall which is subjected to a higher constant temperature than its top counterpart, the sliding lid. For the proposed scheme, the stream function formulation with a weighting function of unity is employed. The simulation results reveal that the local Nusselt number increases with a clockwise increase in the inclination angle. Also, a decrease in the aspect ratio results in an increase in the hot wavy wall average Nusselt number.
Źródło:: Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 519-530
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 3.

Tytuł:: Analysis of controlled molecular dynamic flow in a channel with non-equal inlet and outlet cross-sectional areas
Autorzy:: Najafi, H. R.
Karimian, S. M. H.
Powiązania:: https://bibliotekanauki.pl/articles/279977.pdf
Data publikacji:: 2017
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: molecular dynamics
nano-channel
steady flow
non-equal inlet and outlet
pressure
Opis:: Thermo-fluid properties are required for numerical modeling of nano/micro devices. These properties are mostly obtained from the results of molecular dynamics (MD) simulations. Therefore, efforts have been made to develop methods for numerical evaluation of fluid properties such as pressure and velocity. One of the main challenges faced by numerical simulations is to simulate steady molecular flow in channels with non-equal inlet and outlet boundaries. Currently, periodic boundary conditions at the inlet and outlet boundaries are an inevitable condition in many steady flow molecular dynamics simulations. As a result, a nano-channel with different cross sectional areas at the inlet and outlet could not be simulated easily. Here, a method is presented to generate and control steady molecular flow in a nano-channel with different cross sectional areas at the inlet and outlet. The presented method has been applied to a converging-diverging channel, and its performance has been studied through qualitative and quantitative representation of flow properties.
Źródło:: Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1141-1153
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 4.

Tytuł:: Analysis of pressure behavior in a temperature controlled molecular dynamic flow
Autorzy:: Najafi, H. R.
Karimian, S. M. H.
Powiązania:: https://bibliotekanauki.pl/articles/280901.pdf
Data publikacji:: 2016
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: nanofluid
molecular dynamics
pressure
bin size
sampling
periodic flow
Opis:: Thermo-fluid properties are required for numerical modeling of nano/micro devices. These properties are mostly obtained from results of molecular dynamics (MD) simulations. Therefore, efforts have been put in developing methods for numerical evaluation of fluid properties, such as pressure. In this paper, the pressure behavior in a controllable nanochannel flow is investigated. The nanoflow field is created by imposing a gradient of a macroscopic property such as temperature. Details of the pressure calculation method in a molecular system and its sensitivity to the approximations made are described first. The effect of temperature rise in a uniform flow on the pressure field is studied next. Then, in the flow under a fixed mean velocity condition, the effect of temperature gradient as a controllable property on the pressure field of nanoflow is studied. Velocity, pressure and molecular density of nanoflows with various temperature gradients and different temperature levels are investigated as well. It has been found that the temperature level at which the temperature gradient is imposed, is important. A fixed temperature gradient will not always lead to the same pressure gradient at different temperature levels. Furthermore, quite interestingly, it is observed that at a fixed temperature gradient, with the variation of mean velocity the pressure field also varies.
Źródło:: Journal of Theoretical and Applied Mechanics; 2016, 54, 3; 881-892
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 5.

Tytuł:: Morphological and physiological traits in seedlings’ populations obtained from the hybridization of promising genotypes of quince (Cydonia oblonga Mill.)
Autorzy:: Tatari, M.
Jafari, A.
Najafi Solari, H.
Powiązania:: https://bibliotekanauki.pl/articles/1078110.pdf
Data publikacji:: 2020
Wydawca:: Instytut Ogrodnictwa
Tematy:: morphological trait
physiological trait
seedling
hybridization
quince
Cydonia oblonga
annual growth
iron content
chlorophyll content
catalase activity
peroxidase activity
Opis:: Some morphological and physiological traits of seedlings in eight quince populations from seeds obtained in 2015 (350 progenies per population) were evaluated in 2017 and 2018. They resulted from open pollination of ‘Viduja’, KVD2 and KVD4 genotypes as well as from the crossings of ‘Viduja’ × KVD4, KVD2 × ‘Viduja’, KVD2 × KVD4, KVD4 × ‘Viduja’ and KVD4 × KVD2. Populations showed significant differences in some measured traits, including height and diameter of seedlings, canopy width, annual growth, leaf iron, and chlorophyll content, as well as catalase and peroxidase activities. Based on the results of descriptive statistics, a high variation coefficient was observed in canopy width, peroxidase activity, chlorophyll, and iron content traits. Results of simple correlation showed that there were significant positive correlations between leaf iron content and catalase activity as well as canopy width with both annual growth and leaf length. Cluster analysis among populations based on total traits divided the populations into four distinct groups. The role of the female parents was visible in reciprocal crosses of ‘Viduja’ × KVD4 and KVD2 × KVD4, but all populations with similar female parents were not grouped in the same clusters.
Źródło:: Journal of Horticultural Research; 2020, 28, 2; 53-60
2300-5009
Pojawia się w:: Journal of Horticultural Research
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 6.

Tytuł:: Characteristics of sunflower seed drying and microwave energy consumption
Autorzy:: Darvishi, H.
Hadi Khoshtaghaza, M.
Najafi, G.
Zarein, M.
Powiązania:: https://bibliotekanauki.pl/articles/26490.pdf
Data publikacji:: 2013
Wydawca:: Polska Akademia Nauk. Instytut Agrofizyki PAN
Opis:: The effect of the microwave-convective drying technique on the moisture ratio, drying rate, drying time, effective moisture diffusivity, microwave specific energy consumption, and energy efficiency of sunflower seedswere investigated.Drying took place in the falling rate period. Increasing the microwave power caused a significant decrease in the drying time. The drying data were fitted to four thin-layer drying models. The performance of these models was compared using the coefficient of determination, reduced chi-square and root mean square error between the observed and predicted moisture ratios. The results showed that the Page model was found to satisfactorily describe themicrowave-convective drying curves of sunflower seeds. The effective moisture diffusivity values were estimated from Fick diffusion model and varied from 1.73 10-7 to 4.76 10-7m2s-1. Increasing the microwave power resulted in a considerable increase in drying efficiency and a significant decrease in microwave specific energy consumption. The highest energy efficiency and the lowestmicrowave specific energy consumption were obtained at the microwave power of 300 W.
Źródło:: International Agrophysics; 2013, 27, 2
0236-8722
Pojawia się w:: International Agrophysics
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 7.

Tytuł:: A modified nanoporous stir bar for simultaneous determination of Cu(II) and Cd(II) ions in natural samples prior to flame atomic absorption spectroscopy
Autorzy:: Karimi, M.
Aboufazeli, F.
Zadeh Zhad, H. R. L.
Sadeghi, O.
Najafi, E.
Powiązania:: https://bibliotekanauki.pl/articles/780050.pdf
Data publikacji:: 2013
Wydawca:: Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:: stir bar sorptive extraction
nanoporous structure
Cd(II) and Cu(II) determination
FAAS
Opis:: In this work, the application of stir bar sorptive extraction (SBSE), as a fast and conventional method, has been investigated for the simultaneous preconcentration and determination of trace amounts of Cd(II) and Cu(II) ions in natural samples. For this purpose, the surface of stir bar was functionalized by amine functionalized nanoporous silica and characterized by IR spectroscopy, X-ray powder diffraction (XRD), Atomic force microscopy (AFM) and N2 adsorption. In this approach, after the preconcentration of Cd(II) and Cu(II) ions and removing the matrix interferences using modified stir bar, the amounts of these ions were determined in eluent by flame atomic absorption spectroscopy (FAAS). Various parameters on adsorption and elution steps including pH of sample, adsorption kinetic, eluent parameters (type, volume and concentration) and elution time, have been optimized in this study. The limits of detection (LOD) were 1.6 and 13.8 ng mL-1 (recovery of 83.5 and 88.1%) for cadmium and copper ions, respectively. The preconcentration factors were 133 and 137 and the relative standard deviations (RSD) of the method were 5.7 and 4.6% for Cd(II) and Cu(II) ions, respectively. As the key point in this study seems to be stir bar nanoporous structure, the analytical performance of this stir bar was compared to non-porous ones. The accuracy of this novel method has been confirmed using some standard references materials. Finally the potential of this method was investigated by determination of Cd(II) and Cu(II) ions in some real samples with complicated matrixes.
Źródło:: Polish Journal of Chemical Technology; 2013, 15, 2; 86-93
1509-8117
1899-4741
Pojawia się w:: Polish Journal of Chemical Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Informacja

Wyszukujesz frazę "Najafi, M." wg kryterium: Autor

Źródło danych

Dostawca treści

Kolekcja

Rok wydania

Wydawca

Temat

Autor

Typ dokumentu

Język