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Showing 4 results for Ershadi


Volume 2, Issue 1 (Winter 2022)
Abstract

One of Hakim Sabzevari's arguments on the reasoner and reasonable union of "matter and form" is the argument, in which he considers the ontological principles of matter, form, and soul on the one hand, and on the other hand, he has put the view of Sadra's psychology as the basis for the completion of this argument. In order to distort all the arguments of Hakim Sabzevari, a published article accusing Hakim of "gross confusion" in recognizing the basic contents of philosophy. In this regard, in refuting the argument of matter and form, that article has turned to two major accusations. On the one hand, Hakim has been accused of using allegorical syllogism instead of argumentative syllogism, and on the other hand, it has condemned Hakim for the objection of confiscation. The analysis shows that this argument is based on total unity and that article has been distorted both in terms of reporting and in judgment, it has deviated to adopt illogical positions.
 

Volume 4, Issue 3 (9-2016)
Abstract

Directional felling of trees plays a key role in reducing of damages to forest residual trees and can also facilitate skidding. The aim of this study was presents a practical linear model for estimation of tree falling direction error in an uneven-aged mixed stand in northern forests of Iran. To conduct the study a number of 95 trees of four species Fagus Orientalis Lipsky, Carpinus Betulus L., Alnus Subcordata C.A. May and Acer Platanoides were randomly selected,and assumed felling direction were  marked on the trunk of these trees. The trees felled by experienced chainsaw operators, and the differences between the assumed and actual direction were measured as the felling error. The results showed that among the 12 effective factors, the elements of foot slope, diameter at the breast height (DBH), horizontal and vertical angles and area of the backcut surface (HABS, VABS, BA),vertical angle and area of undercut surface (VAUS, UA) significantly correlated with the felling error, and the determination coefficient (R2) of presented linear model was 52.0 % (P < 0.01). Among the model factors, DBH, VABS, and HABS had the three most pronounce impact on felling error.

Volume 18, Issue 3 (9-2018)
Abstract

Weirs are one of the common structures for regulating and measuring of flow. Also, this structures with different forms such as normal weir, side weir and ogee spillway are widely used for various purposes. In some cases, due to practical restrictions the ogee spillways with curvature in plan are designed. An ogee spillway is located at the top of the reservoir of dam. Dams may also have bottom outlets with valves or gates which may be operated to release flood, and a few dams lack overflow spillways and rely entirely on bottom outlets. In such situations study of flow distribution over the ogee spillway and other related parameters, might be important. In this study, the flow field over thw ogee spillways in axial arc condition was simulated by FLOW-3D software. In the FLOW-3D model, the Navier-Stokes and continuity equations were discretized using the finite difference method. The computational domain was divided into a mesh of rectangular cells. All variables (except for velocity values) were placed at the center of the computational cells (staggered grid arrangement). To solve the governing equations, control volumes were defined around each dependent variable. The surface fluxes, body forces and surface stresses were computed in terms of surrounding variables. Most terms in the governing equations were explicitly evaluated. To solve the flow field of a non-compressible fluid, the continuity and the Navier-Stocks equations were solved. On the other hand, to validate the numerical results, the experimental measurements that were performed in Soil Conservation and Watershed Management Research Institute at reservoir with dimensions 1.4 m length, 0.30 m width and 0.18 m height. The experimental model was made of plexiglas plates which was a model of prototype at the scale of 1:75. Moreover, to measure the flow discharge, a sharp triangular weir with apex angle of 90˚ in the output of channel was used. The flow field turbulence was modeled using the standard and the RNG turbulence model. According to numerical model results, the RNG turbulence model had more accuracy than the standard turbulence model. Also, variations of flow free surface were reconstructed by volume of fluid (VOF) scheme. In this numerical model, the effects of the side symmetrical walls of ogee spillway were examined for cases 60o, 90o and 120o in discharges 34, 34 and 22.6 lit/s, respectively. The applied boundary conditions were chosen according to the physical model. Therefore, the depth and discharge specific values were for inlet boundary condition. At the outlet boundary of the model, the outlet boundary condition was used. All the solid walls of the model were defined as the “Wall” boundary conditions. Also, a symmetry plane was determined at the top layer of the computation field. According to numerical results, the acceptable agreement was obtained between numerical results and experimental measurements. For example, the relative error percent of longitudinal profiles of flow free surface were calculated 12.83, 13.60 and 3.48 percentage for cases 120o, 90o and 60o, respectively. Also with increasing angle of axial arc, the height of rooster tail increased significantly. In addition, by increasing Froude number, the height of rooster tail reduced.

Volume 19, Issue 122 (April 2022)
Abstract

The results of this study showed that the highest amount of linoleic acid in the offspring resulted from the cross between female parent genotype of MSG15 with pollinizers of MKG24 was 57.42 % and the lowest value in the pollinizer of MKG10 was 47.11%. Also, the highest amount of oleic acid was found in the MKG10 pollinizer in the amount of 27.33 % and the lowest in the offspring resulted from the cross between female parent genotype of MKG15 with pollinizers of MKG24 was observed 19.78%. The highest amount of linolenic acid was obtained in pollen parent of MKG10 with 19.30% and its lowest value with 13.88%was found in the offspring of MKG24 parent that pollinated by self-pollen. The highest amount of palmitic acid with 5.80% resulted in self-pollination of MKG24 parent and the lowest value was observed 3.30% in MKG10 pollinizer. The maximum amount of stearic acid with 3.11% was obtained in the offspring from self-pollination of MKG24 and the minimum value with 1.27%was found in the MKG5 pollinizer and offspring resulted from the cross between seed parent genotype of MKG23 and pollinizer of MKG5

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