Showing 18 results for Yarahmadi
Volume 1, Issue 1 (Autumn 2017)
Abstract
In this research,nanocomposite coatings based on epoxy containing pristine graphene oxide and starch-modified graphene oxide are prepared and characterized by Fourier transfer infrared spectroscopy, andtheir crosslinking behavior is studied using nonisothermal differential scanning calorimetry.These nanocomposites, because of having platelet-like nanomaterials inside and their organic origin, can be applied as coating on metal surface in diverse industries.The reason behind using starch was its natural basis and abundance of hydroxyl groups in its structure which can take part in crosslinking reaction with epoxide. Neat epoxy systems having amine curing agent, and nanocomposites containing epoxy, amine curing agent, andpristine or starch-modified graphene oxide nanosheets were cure at different heating rates to assess their curing behavior. Change in hearing rate of test caused change in onset and peak temperature of the exotherm curves and consequently heat of reaction changed. It was observed that the presence of the graphene oxide nanosheets hindered the crosslinking reactions, while surface modification of them with starch natural polymer compensated for such a hindrance via catalytic role of starch, and increased crosslink density of system.
Volume 5, Issue 2 (6-2016)
Abstract
Tetranychus turkestani is one of the most important pests of greenhouse plants in the southern provinces of Iran. Several benefits of using essential oils over chemical pesticides make them appropriate for IPM programs. Contact and fumigant toxicity of the essential oils of Foeniculum vulgare and Citrus limon against the spider mite and its predator, Orius albidipennis were investigated under laboratory conditions. Contact toxicity experiments were conducted at six concentrations, (0, 50, 100, 300, 800 and 2000 ppm) of each essential oil on the mature and immature life stages of the pest, and mortalities were recorded 72 h after exposure. In fumigant toxicity trials, LC50 values of the essential oils were determined on different developmental stages of T. turkestani and O. albidipennis. At 800 and 2000 ppm, both essential oils had high contact toxicity on the eggs, 2nd instar nymphs and adults of T. turkestani, while the same concentrations caused less mortality on O. albidipennis. No significant phytotoxicity of the essential oils was observed. The mortality rates of T. turkestani and O. albidipennis increased as concentration was increased. Also, the 2nd instar nymph of T. turkestani was more sensitive to contact application of the essential oils than other developmental stages. In the fumigant toxicity bioassay, LC50 values of the essential oil derived from F. vulgare on the egg, 2nd instar nymph and adult of T. turkestani were 16.08, 7.98 and 14.06, and the values for C. limon essential oil were 11.6, 9.86 and 11.52 µl × l-1air, respectively. The highest fumigant toxicity was observed against the 2nd instar nymphs of the mite. Fumigant toxicity of the essential oils was lower against O. albidipennis than against T. turkestani. This data suggests that the essential oils of these plants have the potential of being employed in the IPM programs of T. turkestani in greenhouse crops, especially cucumber.
Volume 5, Issue 3 (9-2016)
Abstract
Tomato leaf miner, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is one of the most destructive pests of tomato in many parts of the world including Iran. Field studies were conducted to determine the short and long term effects of Bacillus thuringiensis var Kurstaki (Bt), azadirachtin (AZ), a mix of AZ + Bt, and indoxacarb, as a current chemical insecticide, on T. absoluta larvae. Also, effects of the insecticides were studied on the coexisting generalist predators, Coccinella septempunctata L., Chrysoperla carnea Stephens and Syritta sp. Sampling of T. absoluta and its coexisting generalist predators were performed 1 day before treatment (DBT) and one, 5, 8, 14 and 19 days after treatment (DAT). The results indicated significant short term effect of indoxacarb on the pest larvae. Indoxacarb reduced T. absoluta density and damages. Bt, AZ and mixture of them significantly suppressed the larval density at 19 DAT and caused significant reduction in leaf, stem and fruit damage. The highest long term effect on the pest abundance and damage were observed in Az + Bt caused 100% reduction in fruit and foliage damage compared to the control. The highest and lowest adverse effects on C. carnea, C. septempunctat and Serrita sp. were observed in indoxacarb and Bt treatments, respectively. Findings of this study imply that the mixture of Az + Bt has the highest selective toxicity on the pest and the lowest effect on its coexisting generalist predators.
Volume 5, Issue 3 (9-2016)
Abstract
This is the first report of two ectoparasitoid wasps, Elachertus inunctus (Nees, 1834) in Iran and Elachertus pulcher (Erdös, 1961) (Hym.: Eulophidae) in the world, that parasitize larvae of the tomato leaf miner, Tuta absoluta (Meyrick, 1917) (Lep.: Gelechiidae). The specimens were collected from tomato fields and greenhouses in Ahwaz, Khouzestan province (south west of Iran). Both species are new records for fauna of Iran. The knowledge about these parasitoids is still scanty. The potential of these parasitoids for biological control of T. absoluta in tomato fields and greenhouses should be investigated.
Volume 6, Issue 20 (6-2018)
Abstract
The doppelgänger (twin stranger) with all its dimensions and effects, is one of the oldest beliefs among different nations of the world. This element, originated from mythology, has survived in various ways in the beliefs of the people all around the world. In some cases, the deformation and nature of the data are proportional to human knowledge. In a sense; the belief in the existence of doppelgänger, originated from fear of death and desire to survive. The twin can be examined in terms of shadow, twin, fetal pairs, and image in water or mirror from the perspective of psychology, myth, medicine, storytelling, etc. In this article the authors have discussed the nature and origin of doppelgänger in Iran and the world. Then, the reflection of those beliefs in the culture of Lak's has been definitely considered a continuation, and in some cases the same beliefs that exist among other ethnic groups in Iran and in the world. For many reasons, it can be said that these beliefs are still highly valued in some of the region's villages and among the elders and they are considered indestructible to their beliefs, However, among the young and educated generation, they are no longer superstitious. This research has been conducted on the basis of field library studies through descriptive-analytical methods and, in some cases, based on verbal statements.
Volume 7, Issue 3 (7-2018)
Abstract
Habrobracon hebetor Say (Hymenoptera: Braconidae) is one of the parasitoids which is used against various lepidopteran insect pests in Iran. Due to extensive application of chemical pesticides in farms, studying their side effects on natural enemies is necessary in order to evaluate their probable detrimental effects, in case of application in IPM programs. In this study, side-effects of two prevalent insecticides, flubendiamide and azadirachtin, on functional response of H. hebetor to different densities of 5th instar larvae of Ephestia kuehniella Zeller were evaluated in laboratory conditions. Host densities of 2, 4, 8, 16, 32 and 64 were exposed to randomly selected treated females of H. hebetor in Petri dishes. Ten replications were considered for each host density. The control was treated with water. The results revealed a type ΙΙ response for all treatments. This study showed that flubendiamide and azadirachtin had the lowest (0.269h) and highest values (1.822h) of handling times, respectively. Also, the highest and lowest values of searching efficiency were observed in the flubendiamide (0.188h–1) and azadirachtin (0.0396 h–1) treated wasps, respectively. According to the results of the study, flubendiamide may be more compatible with biological control agent in IPM programs.
Volume 7, Issue 4 (9-2018)
Abstract
Agrotis segetum (Denis & Schiffermüller) is an important polypahgous pest of sugar beet fields in many regions of world including Iran. Biorational pesticides are good and safe alternatives to the chemical insecticides which are compatible with goals of IPM programs. In this study, efficacy of three biorational pesticides, Azadirachtin (NeemAzal®), Bt (Bactospeine®) and Bt (Biolep®), and a conventional chemical insecticide, deltamethrin (Decis® EC), was studied on pest population and damages as well as carabid beetle population as its important predators in sugar beet field during two agricultural seasons (2015 and 2016). Sampling of the pest egg batches, larvae and the carabid beetles was carried out at 1 day before treatment (DBT) and 1, 3, 7 and 10 days after treatment (DAT). Finally, total yield and sugar content of sugar beet in the different treatments were evaluated for the two agricultural seasons. Results showed that NeemAzal was a significant oviposition deterrent for female moths of A. segetum. During both agricultural seasons, the highest and lowest larvicidal effects were observed in Decis and Bt (EC) treatments, respectively. Ten DAT, 40, 60, 13 and 73% reductions of pest population larvae were observed were observed in NeemAzal, Bt (WP), Bt (EC) and Decis treatments, respectively. Sugar beet yield in all treatments was significantly higher than control. Total yields in NeemAzal, Bt (WP), BT (EC) and Decis treatments were 17.5, 25.6, 12.9 and 43.7% more than control in 2015 and 8.7, 19.7, 4.8 and 37.1% respectively in 2016. But sugar content in the different treatments was not significantly different. Totally, the most adverse effects on carabid beetles were recorded in Decis® treatment.
Volume 9, Issue 4 (8-2020)
Abstract
The life table parameters of the parasitoid wasp, Aenasius bambawalei Hayat (Hym.: Encyrtidae) were studied at 25, 30, and 35 °C, 65 ± 5% R. H. and 14L: 10D h. Third instar nymphs of Pseudococcus solenopsis Tinesly (Hem.: Pseudococcidae) were used as host for the wasp. Adult longevity and preoviposition period of female wasps were assessed and the raw data were analyzed using the age-stage, two-sex life table. According to the results, the total preovipostion period of females was 17 days at 25 °C and decreased to 13.07 days at 35 °C. The highest and lowest longevity was recorded for females at 25 °C (40.12 days) and males at 35 °C (3.71 days), respectively. The intrinsic rates of increase (r) of A. bambawalei were 0.1192, 0.1599, 0.2142 d-1 at 25, 30 and 35 °C, respectively. The net reproductive rate (R0) was calculated to be 38.04, 55.30, and 81.22 eggs/individual at 25, 30 and 35 °C, respectively. The mean generation time (T) of A. bambawalei ranged from 20.52 days at 35 °C to 30.52 days at 25 °C. Our results suggested that A. bambawalei may be a more efficient biological control agent for P. solenopsis at 35 °C than at 25 and 30 °C.
Volume 9, Issue 4 (Fall 2021)
Abstract
Aims This study has been done to investigate the effects of access road network of Arasbaran forest areas on erosion in order to achieve appropriate criteria for sustainable development in forest areas while protecting forest soil.
Materials & Methods This research was carried out to introduce the SEDMODEL and its capabilities in estimating the production of sediment from road construction Sutanchay watershed in Arasbaran forest, located in the northwest of Iran. From road networks, 10km selected for research. Initially, the maps of geology, slope, rainfall, and drainage density, were prepared in the GIS system. Then, excavation trenches, road surface coverage, and traffic volume were examined in 34 stations through field surveys. The statistical method of Fisher distribution was used to compare the model estimation and observation values.
Findings Statistical analysis of the data showed that there was no significant difference between sediment delivery and Metric method in the erosion assessment resulting from access roads. Standard Error of the metric method and the SEDMODEL was calculated to be 1.34×10-3 and 1.37×10-3, respectively. The results showed that sedimentation caused by road surface was more than 19,000tons, of which 240ton are related to 3km of asphalt road and the rest are related to 7km of dirt road. Total sedimentation of the watershed was estimated to be 46,000ton.
Conclusion The application of sediment delivery model provides a realistic estimate of forest soil erosion caused by the road network. This model can be considered as a planning criterion in the sustainable development of forest areas.
Volume 10, Issue 3 (6-2021)
Abstract
The cabbage aphid, Brevicoryne brassicae (Hemiptera: Aphididae), is an important pest of rapeseed. In this study, the effects of a silicon-based fertilizer, silicate potassium (SP), and salicylic acid (SA) on inducing resistance in rapeseed to the aphid were studied under field conditions. The rapeseed plants were directly sprayed with SP and SA at two application rates, and the population density of alive and parasitized aphids by Diaeretiella rapae (Hymenoptera: Braconidae) was recorded every three days. The results showed that the aphid population densities in SP and SA treatments were significantly lower than in control (2.21 and 3.53 folds, respectively). The lowest population density was observed in the SP treatment (1200 g/ ha). Moreover, the parasitized aphid densities in the treatments were significantly increased, and the highest parasitism was recorded in the SP treatment (1200 g/ha). The rapeseed yield in the SP-treated plants was significantly more than control, and the highest yield increase was observed in SP treatment (1200 g/ha). According to the results, SP at 1200 g/ha is recommended for cultural control of B. brassicae in the rapeseed fields.
Volume 14, Issue 3 (11-2014)
Abstract
To control the outer bend of river from scour different structures such as spur dike, bendway weir and submerged vane can be used for modification of flow pattern. With interaction of these structures and water flow scour around structure occurs that is the main cause of their failures. It is assumed that the change of geometry and layout of structure can change bed topography for its stability and that is the purpose of the present study. Therefore, in this study a Triangle-shaped spur dike with different angles (23, 30, 40, 60 and 70 degrees) to the upstream direction under different hydraulic conditions (Froude numbers 0.194, 0.214, 0.233 and 0.253) was tested. For all experiments, single Triangle-shaped spur dike was installed outside bend of flume in 72° position which maximum scour depth is usually occurring. For all experiments, flow depth was kept constant equal to 13 cm. At the end of each experiment bed topography was measured and from that the scouring zone, maximum scour depth and distance of scour hole was computed. The results showed that the overall scour hole is created in toe of the spur dike that is expanded to the upstream and downstream structure. Triangle-shaped spur dike with 23 and 60 degree installation was found to create the minimum and maximum scour depth as well as its distance from the outer bank respectively. The maximum scour depth for spur dike with angles of 23 and 60° was measured to be 0.127 and 0.496 of the spur dike effective length respectively. In addition, the maximum scour depth distance of above mentioned angles from the outer bank was respectively, 0.743 and 1.6 the effective length of structure. Eroded sediments were deposited downstream the spur dike and point bars are developed. By increasing of spur dike angle, the point bars are formed away from the outer bank and extended in flume width. For spur dike angles of 23 and 70° the point bar distance from the outer bank was equal to 0.228 and 0.365 effective length of the structure respectively. To control the outer bend of river from scour different structures such as spur dike, bendway weir and submerged vane can be used for modification of flow pattern. With interaction of these structures and water flow scour around structure occurs that is the main cause of their failures. It is assumed that the change of geometry and layout of structure can change bed topography for its stability and that is the purpose of the present study. Therefore, in this study a Triangle-shaped spur dike with different angles (23, 30, 40, 60 and 70 degrees) to the upstream direction under different hydraulic conditions (Froude numbers 0.194, 0.214, 0.233 and 0.253) was tested. For all experiments, single Triangle-shaped spur dike was installed outside bend of flume in 72° position which maximum scour depth is usually occurring. For all experiments, flow depth was kept constant equal to 13 cm.
Majid Yarahmadi, Somayeh Chegini,
Volume 17, Issue 1 (3-2017)
Abstract
In this paper, a quantum intelligent robust controller via a combination of sliding mode control with boundary layer and quantum neural networks, for uncertain nonlinear systems in presence of external disturbances, is presented. Based on the adjustable time variant rejection regulator and rejection parameter, a time variant sliding surface as an adaptive chain of the first ordered low pass filters is defined. A three layers quantum neural network is designed to identify the uncertain nonlinear functions in system dynamics. In this method, the control gain and the break-frequency bandwidth are tuned adaptively. Also, the effects of uncertainties and the un-modeled frequencies are eliminated and chattering phenomenon doesn’t occur. Also, for facilitating analytical theory of the presented method and derivation of the adaptive laws a theorem is proved. Finally, the simulated examples show that the proposed method presents an intelligent adaptive robust tracking control such that the control amplitudes and the integral absolute error index of the tracking trajectory are much less than the other methods. Therefore, effective identification, eliminating the effects of system uncertainties, adjustable control gain and break-frequency bandwidth and more accurate tracking are some of the advantages of this method.
Keywords
Zeinab Sahebi, Majid Yarahmadi,
Volume 18, Issue 2 (4-2018)
Abstract
In this paper, a new hybrid adaptive intelligent controller is introduced to track a dynamic trajectory in finite dimensional closed quantum systems. The problem of inherent singularities in control signals of trajectory tracking in quantum systems leads to a sharp increase in control signal amplitude. As a result, the amplitude of the large signal increases the control cost and control system instability. Consequently, the large control signal amplitude increases the control cost and leads to instability in control system. Firstly, according to the Lyapunov stability theory, an adaptive controller is designed to track the dynamic path. Then, to overcome the singularity drawback, a quantum intelligent controller is designed based on a quantum adaptive wavelet neural network with batch back propagation learning and combined with adaptive controller by a singularity observer. The proposed hybrid adaptive intelligent controller by combining the adaptive and intelligent control signals adjusts the quantum state so that the desired dynamic trajectory is traced effectively and simultaneously eliminates the effects of singularities and reduces the control amplitude. The performance of the hybrid adaptive intelligent controller is checked for step response tracking in a population transfer of a four-level closed quantum system. The simulation results show that the introduced controller reduces the tracking error and significantly decreases the number of singular points. Also, the control cost is reduced by effective adjustment of the control signal’s amplitude.
Volume 20, Issue 2 (5-2020)
Abstract
Speeding contributes to increased frequency and severity of road crashes. Strengthening deterrence of speeding requires imposing effective penalties for non-compliance with speed limits, as well as effective enforcement of the legislation. Yet, different monetary and non-monetary penalties have been proposed for offensive drivers. The literature, however, lacks evidence on relative deterrence of existing penalties and the way the drivers respond to new forms of penalty systems. This study is among the first that investigated relative deterrence of different speeding penalties including “monetary fines”, “demerit point”, “car detention”, and “social deprivation”. Questionnaire was designed based on choice experiment method (CEM) with considerations of balance and orthogonality. Convenience sampling method was used to collect data in campuses of Kharazmi University in Karaj, College of Engineering in University of Tehran, and East Tehran Branch of Islamic Azad University, which all are among the largest university campuses in the country. A total of 550 questionnaires including 2004 choices were conducted (response rate: 91.1%). Using an indirect approach, we conducted a mixed logit (ML) model to estimate the drivers’ willingness to pay (WTP) for non-monetary speeding penalties. Results indicated that “social deprivation” would offer stronger deterrence compared to other penalties. Deterrence effect of “monetary fines” and “demerit point” increases with increase in drivers’ age. Findings emphasized that further development of non-monetary penalties in the future would increase deterrence of speeding violations.
M. Yarahmadi, M.m. Shahmardan, M. Nazari,
Volume 20, Issue 9 (September 2020)
Abstract
The subcooled flow boiling happens when the bulk flow temperature and the interface temperature are lower and higher, respectively than the saturated temperature corresponding to the flow pressure. One way to increase the heat transfer mechanism is to use high porosity metal foams in the ducts, which have a high surface area to volume ratio that increases the heat transfer surface area and the heat transfer coefficient of the duct. In the current study, an experimental apparatus was constructed, and subcooled flow boiling in an annulus tube was investigated. The annulus tube is in the vertical direction, and the internal and external diameters are 50.7 and 70.6mm, respectively. The operating pressure was 1atm, and the working fluid was water. The metal foam used is nickel with 10ppi and a porosity of 95%. In this investigation, heat flux and mass flow rate effectiveness on the heat transfer coefficient are considered. The experiments were performed in the mass flow rate range of 0.012kg/s to 0.0286kg/s in which the flow consists of both forced convection and flow boiling. The mass flow reduction causes the heat transfer coefficient increment to 30% in subcooled boiling regions. The use of porous media also increases the subcooled flow boiling heat transfer coefficient up to 30%.
Volume 23, Issue 3 (5-2021)
Abstract
The hemipteran, Macrolophus pygmaeus Rumber, is an effective biocontrol agent against many crop pests including tomato leaf miner, Tuta absoluta Meyrick. Sublethal effects of azadirachtin (Neem Azal®), indoxacarb (Avaunt®), and emamectin benzoate+lufenuron (Proclim Fit®) were studied on biological characteristics and functional response of the predatory bug in laboratory conditions at 25±1°C, 6 ±5% RH, and a photoperiod of 16:8 hour (L:D). For this purpose, females of the predatory bug were exposed to sublethal residues (10% of field concentration) of the insecticides. Two-sex life table and Roger's model were used to investigate effects of the insecticides on biological parameters and functional response of the predator, respectively. Results indicated that sublethal residues of indoxacarb and azadirachtin had the highest and lowest side effects on life table parameters of M. pygmaeus. Whereas azadirachtin has no significant effects on the bug biological parameters, total fecundity and longevity of the bug in indoxacarb treatment were significantly lower (14.6%) and higher (6.9%) than the control. The predator showed type III functional response. The type of functional response was not affected by the insecticide residues. However, the coefficient of attack rate (b) for the indoxacarb treatment (0.1521) was significantly lower than for other treatments. However, there was no significant difference between the handling Times (Th) of the treatments. In conclusion, the experiments proved that azadirachtin is a low risk insecticide to M. pygmaeus, which can be integrated with biological control by the predator.
Farshid Jafarian , Mohammad Meghdad Fallah , Mohsen Bahrami Yarahmadi ,
Volume 23, Issue 10 (October 2023)
Abstract
The development of reliable numerical tools for predicting the integrity of machined surfaces is significant. This paper introduces a new customized FE model to predict the deformation during turning of electron beam fused (EBM) Ti6Al4V alloy under dry cutting. The needle microstructure and exotic nano-hardness types of materials are modeled and implemented using a user subroutine in the FE model. The developed FE model provides the possibility of predicting the microstructure (thickness of alpha lamella), the changes in nano-hardness caused by machining operations in dry conditions.
Farshid Jafarian , Mohammad Meghdad Fallah , Mohsen Bahrami Yarahmadi,
Volume 23, Issue 10 (October 2023)
Abstract
Titanium and its alloys, especially the Ti6Al4V alloy, have many uses in the aerospace and medical industries due to their unique properties. The production of Ti6Al4V alloy by additive method has been very much considered due to the characteristic of this method. But due to the fact that these parts also require final machining. As a result, it is very important to achieve optimal parameters from a faster and more economical method. In this article, simulation of cryogenic machining of EBM Ti6Al4V alloy in order to study microstructural changes. done. It was validated by comparing the experimental results and simulation of the material model. Then, using the validated FE model, the effects of shear speed on forces, thermal loads and microhardness were discussed.