Showing 52 results for Pol
Volume 0, Issue 0 (ARTICLES IN PRESS 2024)
Abstract
Powdery mildew (PM) of chilli is one of the major diseases affecting the yield and quality of chilli. Pathogen perpetuates in the infected crop debris and produce airborne conidia for rapid secondary spread. Prophylactic application of fungicides is admissible to keep the disease under threshold. Therefore, an experiment was designed to determine bio-efficacy and phytotoxicity of different doses of a new molecule combination (i.e KK-21: Sulphur 84% + Azoxystrobin 6% SC) along with optimization of its number of sprayings. This molecule was also compared with the most popularly used fungicides against PM of chilli. Additionally, influence of weather variables on the initiation and progression of the disease were also studied and prediction model developed by stepwise regression equation for timely forecasting and managing the disease. Study revealed, depending upon the prevailing weather the disease first appears between 44 to 64 days after transplanting then progress gradually at a rate varied from 0.0012 to 0.0139. Among the fungicides applied, three spraying of KK-21 @ 2500 ml/ha at 15 DI just after initiation of the disease was most effective with lowest disease severity index (5.00) and highest yield 150.24 q ha-1 and no phytotoxic effect was recorded even at higher dose. Result also showed, maximum temperature and relative humidity had significantly positive and negative correlation with the disease severity and the prediction equation demonstrated that these two factors could explain 78.2 - 87.6% of the variation in disease severity.
Volume 5, Issue 3 (Summer 2023)
Abstract
Introduction
The land of Iran is located in a belt of dry and desert areas of the earth, which suffers the most unfavorable effects from climate change. Climate change is evident in the Zayandehrud basin, and its effects are evident in the decrease of rainfall and increase in temperature in recent years, as well as the continuation of droughts in the Zayandehrud watershed. With the reduction of river water flow, the allocation of water to the agricultural and environmental sectors in the middle and downstream parts has faced a problem. The need for water in this basin is high, so that during these years, the effort to obtain water in the Zayandehrud basin has entered a new arena in the form of tension, conflict, protests, and social unrest. One of the most important consequences of climate change is that it forces governments to plan inter-basin transfers. As a result of the water transfer policies without taking into account the religious rights and the environmental rights of the Zayandehrud bed and the Gavkhoni wetland, many social differences between the provinces have intensified.
Methodology
In terms of its purpose, the current research is an applied research that considering the historical, geographical, economic and political importance of the area, identifies the dimensions and effects of climate change in the Zayandehrud watershed and explains how climate change can increase crisis and tension in the watershed. This can be a useful guide for planners and decision makers in the field. In terms of method and nature, this research is descriptive-analytic, and the method of data gathering procedure is based on library sources, including books, magazines, and databases.
Research findings
The turning of snow into rain at the source of the Zayandehrud and the increase in evaporation has led to the reduction of lands in the downstream part of the river, so that the area of "agricultural" and "pasture" lands has decreased in the middle and downstream parts. The number of wells has increased dramatically in recent years. The number of wells in the middle and downstream parts has increased significantly in this period, the average depth of the wells in the basin has increased by 4.8 meters, which is 6.65 meters in the upstream part, 5.55 meters in the middle part, and 28.28 meters in the downstream part. An average of 6 meters has been added to the depth of the wells. The increase in inter-provincial tensions, of which prominent examples were observed between Khuzestan, Isfahan and Chaharmahal Bakhtiari provinces in recent years, is one of the most important political consequences of climate change, which forces governments to plan inter-basin transfers. Isfahan farmers are the most important group protesting the critical water situation in this basin. One of the most important concerns of the people of the region and the most important cause of strikes and conflicts in recent years is the reduction of water resources and the reduction of agricultural activity. In recent years, the farmers of the region have expressed their protests in various ways, such as breaking and breaking water pipes, strikes, demonstrations and blocking the road with tractors, referring to the province and other ways. Public tension and protests regarding water supply and optimal water management for the residents of Zayandehrud Basin are not limited to the residents and beneficiaries of Zayandehrud Watershed. Hydro-political issues of the Behesht Abad water transfer project in the upper part of the Karun Basin, which has been the cause of local, regional and even national disputes between people and officials at the source and destination. This has caused social and political differences between the residents and beneficiaries of the upstream watersheds and the mentioned watersheds, and due to the ethnic differences of the watersheds, this issue has turned into an internal hydro-political crisis that has created gaps between ethnic groups. Climate change has hit the agriculture sector the most. Also, the first procedural consequence is the increase in the amount of unemployment and the immigration crisis. Immigration has led to the dispersal of kinship relations and the loss of solidarity, ethnic cohesion, and the increase of individualism and isolation, and as a result marginalization and drug addiction. The drying of Zayandehroud riverbed due to climate change has caused numerous cracks and subsidence in different areas of the watershed in Isfahan province. The depth of these cracks is very deep and in some cases they have a depth of more than 10 meters. Cracks have caused serious damages to roads and agricultural land.
Conclusions
Climate change in the Zayandehrud basin is one of the factors that threaten the water resources in the basin. The climate change and decrease in rainfall and the expansion of agriculture and water-bearing industries has led to the destruction of nature and the geographical space and the lowering of the underground water level and even the transformation of permanent rivers into seasonal and seasonal into casual and dry rivers, and to compensate for this situation, the water transfer policy. This approach has caused political and security tensions in this region. Among the hydro-political issues of the water transfer projects in the mentioned catchment basin and its negative social-political consequences can be the intensification of local and regional conflicts and divergences, jeopardizing local and regional security, political activism of people and officials, ethnic diversity and political and regional sensitivities. One of the factors that play a basic role in creating negative political activism caused by water transfer is the strengthening of political regionalism, which itself is caused by weak management policies. This leads to the formulation of "negative hydro-politics" on a national and regional scale, and in turn has negative effects on local, regional and even national security issues.
Mohammad Pol, , ,
Volume 12, Issue 1 (4-2012)
Abstract
In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated experimentally. The glass/epoxy/nanoclay laminate nanocomposites have 12 layers and 60% fiber volume fraction is manufactured by VRTM method. Fibers have a plain weave configuration with density of 200gr/m2, while The epoxy resin system is made of a diglycidyl ether of bisphenol A (DGEBA), Epon 828, as the epoxy prepolymer and a polyoxypropylene diamine with average molecular weight of 400 gr/mol, Jeffamine D-400, as the curing agent. The nanoclay Closite 30B is dispersed into the epoxy system in a 0%, 1%, 2%, 3%, 5% and 7% ratio in weight with respect to the matrix. Morphological studies using XRD revealed that nanostructures are mostly in intercalated form rather than exfoliated form. In additional to tensile test, ballistic impact test is carried out on the samples by flat-ended projectile with 14gr mass and 9.77mm diameter in 130m/s, 142m/s and 155m/s velocities. The results have shown that not only the mechanical properties, but also ballistic impact resistance can be improved with adding nanoclay.
Mohammad Pol, ,
Volume 12, Issue 2 (6-2012)
Abstract
In this paper an analytical model for investigating of the ballistic impact behavior of two dimensional woven E-glass/epoxy composites is presented on the basis dividing the impact duration to several time intervals and calculating the energy absorbed during each time interval. The major components of energy lost by projectile during ballistic impact are identified, namely the cone kinetic energy formed on the back face of the target, the secondary yarns deformation energy, the tensile failure energy of primary yarns, the delamination and matrix cracking energy. It is assumed that the shear plug formation is not observed for glass reinforced composites and the energy lost in overcoming the frictional force between projectile and composite is negligible. Analytical formulations have been presented for calculating energy absorbed by each mechanism in each time interval. Finally, a good correlation has been observed, comparing the analytical model presented in this paper to the experimental results presented by others investigators.
Volume 12, Issue 3 (August & September 2021 (Articles in English & French) 2021)
Abstract
Most studies on Written Corrective Feedback (WCF) have focused either on ESL or EFL teachers’ beliefs and practices. However, it is still not known how teachers who teach second or foreign languages other than English will provide information on the learners’ written language production. To bridge the gap in the literature, this current study reports on an interview study investigating nine university lecturers’ beliefs and their actual practices about WCF on an assignment done by the third-year exchange student of Thai as a foreign language (TFL). Quantitative and qualitative data were collected through feedback tasks and semi-structured interviews. The findings indicated that there was alignment between teachers’ beliefs of their WCF practice and their actual practice in terms of types of WCF and feedback techniques. However, the amount of feedback provided and the teachers’ time constraint, not the level of students’ ability as they thought, appeared to be the reasons for these misalignments of TFL teachers’ beliefs and practices
, Mohammad Pol, ,
Volume 13, Issue 3 (6-2013)
Abstract
Aluminum foam structure is of great importance in aerospace, naval and automotive industries due to light weight and energy absorption characteristics. In this article several aluminum foam having different densities and thickness were designed and tested using light gas gun device. A series of ballistic test were defined in order to determine the effects of density, foam thickness and projectile velocity on energy absorption aluminum foam structures. The results of the experimental testes, it is shown that the amount of energy absorption of aluminum foam structures is increased as density, foam thickness and velocity of the projectile is increased.
Mohammad Pol, , ,
Volume 13, Issue 4 (7-2013)
Abstract
In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated experimentally. The glass/epoxy/nanoclay hybrid laminate nanocomposites are manufactured by layup method under pressure. The nanoclay particles are Closite 30B and are dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the matrix. In additional to tensile test, ballistic impact test is carried out on the samples by flat-ended projectile with 8.9gr mass and 10mm diameter in 134m/s and 169m/s velocities. The results have shown that not only the mechanical properties, but also ballistic impact resistance can be improved with adding nanoclay.
Mohammad Pol, ,
Volume 13, Issue 6 (9-2013)
Abstract
In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated Theoretical and experimentally. The structure of the hybrid nanocomposite is glass/epoxy/nanoclay laminate and is manufactured by hand layup method under pressure. The nanoclay is dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the matrix. Comparison of theoretical results and results of the ballistic impact test are shown a good correlation. The results have shown that optimal to increase in energy absorption is 10% in 3% nanoclay content. Howevere, in the impact velocities far than ballistic impact, maximum increasing in energy absorption is 20% in 10% nanoclay content.
Mohammad Hedayatian, Gholam Hosein Liaghat, Gholam Hosein Rahimi, Mohammad Hosein Pol, Mehdi Khoshsoroor,
Volume 14, Issue 2 (5-2014)
Abstract
In this paper, the experimental behavior of grid cylindrical composite structures which are used widely in engineering structures under ballistic impact is investigated. In the present study, the grid cylindrical composites were manufactured by the filament winding process with fiber placement procedure and perforated by projectile using the ballistic gas gun. Input and output velocities of projectile were recorded. The results show that presence of discrete ribs prevents spread damage from one cell to it’s adjacent cells and structure behaves differently against projectile with velocity near ballistic limit velocity and higher velocities. With approach to the ribs location ballistic limit has been increased. However due to reduce fracture area, overall and local deformations after impact in velocity which is higher than ballistic limit velocity, projectile has been came out from grid samples with higher velocity than simple composite shells. In this paper, delamination in outer composite shell and ribs, debonding between shell and ribs, residual velocity of projectile, fracture area of the grid specimens and the effects of curvature in two deferent velocities were reported and commented upon as results.
Volume 14, Issue 3 (5-2007)
Abstract
The change in the concept of social development over the last few decades, from the physical aspects to human dimensions has increased women’s participation in socio-economic activities and enhancement of their capabilities has been regarded as key strategies in sustainable development. The present study attempts to achieve the following objective: Investigation of the impacts of NGO’s activities in enhancing women’s socioeconomic participation in the management of watersheds.
This paper has presented the results through employing parts of the phases, methodologies, and techniques of participation Rural Appraisal(PRA) in sample villages located in Hableh Roud watershed in the Garmsar plain. Among the achievements of the project is the actualization of local community participation including women’s participation in decision-making on sustainable development, improvement of natural resource management through integration of modern and traditional technologies, increasing local community income sources through production of pharmaceutical plants, planting seedlings, strengthening traditional women’s organizations, improvement of exploitation methods and conservation of soil and water resources. The most important result obtained from the present study is the finding that participatory activities are cultural and social issues. As such, work must continue until participation becomes institutionalized in the target community. The milestone and deliverable showing success in this endeavor will be gradual but steady changes observed in the behavior of the rural communities with reference social and economic problems reflecting their self-reliance and self-confidence. Continuity and sustainability of the projects are also determined by direct involvement and participation of local communities, especially women, in all phases of project implementation from concept development to implementation, monitoring, and assessment.
Abbas Masoudi, Gholam Hossein Lighat, Mohammad Hossein Pol,
Volume 14, Issue 4 (7-2014)
Abstract
: This paper investigated experimentally the effect of nanoclay on ballistic impact behavior of GLARE. The prepared GlARE is made of two Aluminum 2024 facing sheets and E glass/ epoxy/nanoclay as nano composite core. Nano composite section has been composed of undirectional E glass 409 g/m2, resin CY 219, hardner HY 5161 and nanoclay closite 30B dispersed into the epoxy system in a 0%, 4%, 7% and 10% ratio in weight with respect to the matrix. All panels fabricated using laid-up method in fiber volume fraction of 60%. Ballistic tests were conducted using Gas gun at the velocity of 205 and 225 m/s. The results of the ballistic impact experiments show that the amount of Specific energy absorption variations in 4% of nanoclay content is insignificant. However, in nanoclay contents of 7% and 10%, the Specific energy absorption increases. To analyze the results of the ballistic impact on the GLARE, the effect of nanoclay on the longitudinal and transversal mechanical properties of the composite was investigated. A noticeable correlation was found between ballistic impact results and Changes of toughness in longitudinal and transversal direction.
Nesa Pirmohammad, Gholam Hossein Liaght, Mohammad Hossein Pol,
Volume 14, Issue 4 (7-2014)
Abstract
this paper, ballistic impact on sandwich panel with composite facesheet made of Glass/Epoxy and aluminum honeycomb core has been investigated experimentally. Ballistic impact test also carried out on Honeycomb and composite and the effect absorption energy by adding composite on two sides honeycomb is studied. By this model the influence of the components on the behavior of the sandwich panel under impact load was evaluated. Ballistic impact tests is carried out on the samples by flat-ended projectile with 8/5 gr mass and 10 mm diameter in difference velocities. Also, the contribution of the failure mechanisms to the energy absorption of the projectile kinetic energy was determined. The results show that honeycomb sandwich has more energy than when alone ballistic tests conducted on has absorbed and front cover compared with back cover sandwich structure has lower energy absorption. Also bigger than ballistic limit velocity absorbed the maximum amount of energy.
Nesa Pirmohammad, Gholam Hossein Liaghat, Mohammad Hossein Pol, Hadi Sabouri,
Volume 14, Issue 6 (9-2014)
Abstract
In this paper, ballistic impact on sandwich panel with composite face sheet made of Glass/Epoxy and aluminum honeycomb core has been studied. The solution is derived from a wave propagation model. At first both analytical and numerical solutions were clarified and their results were compared with experimental results. Some deformation patterns, failure modes and energy absorption mechanisms were identified by observation, such as: dynamic movement of the target, stretching, bending deformation, delamination, debonding, shear fracture honeycomb, tensile fracture of Glass/Epoxy and plug and petal formation in composite facings. The solution involves a four-stage and effective masses of the face sheets and core as the shock waves travel through sandwich panel are derived using Lagrangian mechanics. The resulting non-linear differential equation of motion was solved considering the local damage effects and corresponding energy absorptions. Also numerical model, analysis of the penetration process was performed by a nonlinear explicit finite element code, LSDYNA. The results of analytical solution and numerical simulation are compared with experimental tests. Ballistic impact tests is carried out on the samples by flat-ended projectile with 8/5 gr mass and 10 mm diameter in difference velocities.
G. H. Rahimi, Reza Zamani, Mohammad Hossein Pol,
Volume 14, Issue 6 (9-2014)
Abstract
This study examines the reinforcing effect of organically modified layered clay on the structure and mechanical properties of the amine-cured epoxy/clay nanocomposites. The epoxy resin system is made of a diglycidyl ether of bisphenol A, Epon 828, as the epoxy prepolymer and Epikure 3234, namely TETA, as the curing agent. The organically modified clay, Closite 30B, is dispersed into the epoxy system in a 0%, 1.5%, 3% and 5% ratio in weight with respect to the matrix. The state of dispersion was characterized by X-ray diffraction method. The results of XRD show that the clay has been further intercalated by the epoxy matrix. The tensile and flexural properties of the epoxy/clay nanocomposites were investigated according to the standard tests. It is found that the tensile and flexural modulus and flexural Strength of the epoxy/clay nanocomposites increase with adding clay loading into the resin. However, the other mechanical properties such as tensile strength, strain at break and energy to break decrease as the clay nanoparticles is added into the resin. The results also approved that the TETA-cured epoxy resin can be more brittle when the clay nanoparticle is added into the epoxy resin.
Abbas Masoudi, Gholamhossein Lighat, Mohammad Hossein Pol,
Volume 14, Issue 7 (10-2014)
Abstract
This paper investigated experimentally and numerically the effect of nanoclay on ballistic impact behavior of GLARE. The prepared GlARE is made of two Aluminum 2024 facing sheets and E glass/ epoxy/nanoclay as nano composite core. Nano composite section has been composed of undirectional E glass 409 g/m2, resin CY 219, hardner HY 5161 and nanoclay closite 30B dispersed into the epoxy system in a 0%, 4%, 7% and 10% ratio in weight with respect to the matrix. All panels fabricated using laid-up method in fiber weight fraction of 60%. Ballistic tests were conducted using Gas gun at the velocity of 205 and 225 m/s. The results of the ballistic impact experiments show that the amount of Specific energy absorption variations in 4% of nanoclay content is insignificant. However, in nanoclay contents of 7% and 10%, the Specific energy absorption increases. In other words, it be concluded that nanoclay has positive effect on higher percentage on the ballistic impact. The 3D finite element (FE) code, LS-DYNA, is used to model and validate the experimentally obtained results. A noticeable correlation was found between experimental and numerical results.
Mohammad Pol, Seyed Abdoelvahab Hoseini,
Volume 14, Issue 7 (10-2014)
Abstract
In this paper, the influence of nanoclay Closite 30B on the tensile and the bending properties of 2D woven E- Glass/Epoxy laminated composite have been investigated experimentally. The glass/epoxy/nanoclay laminate have 12 layers and 60% fiber volume fractionis is manufactured by VRTM method. Fibers have a plain-weave configuration with density of 200 gr/m2, while the nano-epoxy resin system is made of diglycidyl ether of bisphenol A (epon 828) resin with jeffamine D400 as the curing agent and an organically modified MMT in a platelet form, namely Closite 30B. The nanoclay is dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the nano-matrix. The results have shown that Maximum to increase in the tensile and the bending properties are in 3% and 10% nanoclay content. The maximum to increase in the tensile strength, the failure strain and toughness are 13%, 7% and 27% respectively in 7% nanoclay content and in the modulus is 9% in 3% nanoclay content. Moreover, the maximum to increase in the flexural strength is 11% in 3% nanoclay content and in flexural modulus is 48% in 5% nanoclay content.
Mohammad Hedayatian, Golamhossein Lighat, Rahimi, Mohammad Hossein Pol,
Volume 14, Issue 9 (12-2014)
Abstract
Due to the extreme increase in computational power over the recent years, numerical methods have gained the most proportion in analyzing composite structures and components because of the consideration complicated failure mechanisms such as delamination, fiber buckling and fiber breakage, matrix cracking, debonding ribs of skin and a combination of mentioned failure mechanisms. However exact three - dimensional modeling damages caused by impact phenomena is still a challenge. In present numerical work, the most advanced modeling techniques have been used to predict the behavior of composite structure under high velocity impact. The ribs and layers have been modeled using solid elements and a user defined material model with modified puck and Hashin (3D) failure criteria was implemented. Because these failure criteria do not exist in Commercial version of the Abaqus software, we have used Fortran software for writing these criteria so this capability was added to the software. Figures of velocity variations and force variations of projectile, damaged area, different mechanisms of fracture were reported as results and commented upon. In this study, The numerical results have been validated with experimental data and show very good agreement.
Ehsan Zamani, Gholamhossein Liaghat, Mohammad Hossein Pol,
Volume 14, Issue 9 (12-2014)
Abstract
Axial compression behavior of foam materials can be explained by two ideal deformation scenarios: discrete crush band process and progressive collapse. In this paper, a perfectly new model for strength assessment and quantitative/qualitative description of one-dimensional progressive collapse of aluminum foams under impulsive loadings is presented and its capability to split this way of crushing into two distinct regimes of shock wave and elastic- plasic wave propagation is highlighted. Then, using conservation relations and the new introduced model, the analytical solution of dynamic deformation of aluminum foams in the two mentioned regimes is developed. Regime 2 considers the case when the crushing front velocity is lower than the linear sound velocity of the foam; but remains higher than the effective sound velocity for a perturbation in which the amplitude lies in the so-called “plateau region’ of the static stress-strain diagram. The physical difference between this regime and the fiest one entails not only the creation a shock front associated with the collapsing foam, but also an acoustic precursor in the case of second regime.Finite element simulation is also performed to validate the analytical procedure. The numerical prediction is found to be in very good agreement with the analytical results.
Reza Zamani, G. H. Rahimi, Mohammad Hossein Pol,
Volume 14, Issue 10 (1-2015)
Abstract
In this study, the reinforcing effect of organically modified layered clay in two epoxy matrices, TETA-cured and F205-cured, was studied. The epoxy resin system is made of a diglycidyl ether of bisphenol A, Epon 828, as the epoxy prepolymer and the two hardeners were Epikure 3234, namely TETA, and Epikure F205. The organically modified clay, Closite 30B, is dispersed into the epoxy system in a 0%, 1.5%, 3% and 5% ratio in weight with respect to the matrix. The state of dispersion was characterized by X-ray diffraction method. In both systems of epoxy resin, the results of XRD show that the clay has been further intercalated by the epoxy matrix. The tensile and flexural properties of the epoxy/clay nanocomposites were investigated according to the standard tests. The results of mechanical tests indicate that the mechanical behavior of two epoxy resin systems reinforced with clay nanoparticles, are different from each other, so that adding clay into the epoxy matrices makes the TETA-cured nanocomposites more brittle and the others cured with F205 more soften. By comparing the results of two epoxy resin systems reinforced with clay nanoparticles, it is concluded that positive effect of presence of the clay nanoparticles is evident on the mechanical properties of the F205-cured epoxy resin.
Gholam Hossein Liaghat, Sajjad Seifoori, Akbar Ali Beigloo, Mohammad Hossein Pol,
Volume 14, Issue 13 (First Special Issue 2015)
Abstract
In this article, an improved 3D finite element (FE) model of low velocity transverse impact on armchair and zigzag single-walled carbon nanotubes (SWNTs) has been developed. Numerical examples for estimating the Young’s modulus of nanotubes are presented based on explicit and implicit analysis to illustrate the accuracy of this simulation technique. Based on explicit finite element model, the maximum dynamic deflections of single-walled carbon nanotubes with different boundary conditions, geometries as well as chiralities are obtained and then compared with theory investigation. Impact of a mass on simply supported and clamped nanobeams are investigated by using nonlocal Euler–Bernoulli and Timoshenko beam theory. The simulation results demonstrated good agreement with analytical results based on Euler–Bernoulli and Timoshenko nonlocal theory. When the aspect ratio is increased, the maximum dynamic deflection at the center of the beam is increased for both of the simply supported and the clamped-clamped nanobeams. The inclusion of the nonlocal effect increases the magnitudes of dynamic deflections. The dynamic deflections predicted by the classical theory are always smaller than those predicted by the nonlocal theory due to the nonlocal effects.