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Showing 25 results for Moslemi


Volume 1, Issue 1 (Spring and Summer 2024)
Abstract

The theory of the responsibility to protect was approved in 2005 in the output document of the United Nations Summit (A/RES/60/1) and in 2011, it was included in the Security Council Resolution 1973 regarding military intervention in Libya. The theory of the responsibility to protect implies the commitment of the international community to end the worst forms of violence and crime in humanitarian crises and internal armed conflicts. This article by using the qualitative method and document-library sources, books, articles and reports and internet notes, dealing with NATO's military intervention in Libya in 2011, which led to airstrikes, the creation of a no-fly zone, and ultimately the change of Muammar Gaddafi's regime,  criticizes its application in Libya.The findings of the article show that although the theory tries to fill the gap between the former obligations of UN member states under international humanitarian law and human rights with this reality that the human population facing the threat of genocide, crimes against humanity, ethnic cleansing and crimes against humanity must be supported, France, the United States and NATO have exploited the 1973 resolution for their political-military goals and have caused the stoppage of the development of the theory and the skepticism of the international community towards the goals and intentions of the world powers in the application of the theory and as a result of the design of the new approach of responsibility during support.
 

Volume 4, Issue 1 (10-2012)
Abstract

Leisure includes all activities people do after work, family and social obligations. These activities may be done in order to have a rest or hobby, or in order to expand non-profitable training or voluntary social participation. Since leisure time is a modern concept emerged after industrial revolution, this article attempts to study the difference between modern and traditional leisure: In todays modern time, what kind of leisure do people have? Which kind of leisure (modern or traditional) do people have more of? Which kind of social factors (income, gender, marital status, education rate, socio-economic status, residency and age) influence leisure time? Sample size (510 cases) of this survey was determined through Cochran’s formula out of 49967 statistical populations.The samples were selected through stratified multi-step cluster sampling method. The results showed that modern leisure is lower than traditional leisure. All the mentioned social factors, except income, influence leisure time activities.    


Volume 10, Issue 3 (12-2010)
Abstract

- In this paper an analytical model for prediction of angular deformation is presented. In this model convective heat losses and a multipoint distributed heat source is used for determination of the inherent strain zone which causes the bending angle. The effects of laser bending process parameters including laser power, beam diameter, scan velocity and pulse duration on the bending angle were investigated experimentally. Main effects of factors were considered and the regression line was derived. An L9 Taguchi’s standard orthogonal array was employed as experimental design and the level of importance of the laser bending process parameters on the bending angle was determined using analysis of variance (ANOVA). Comparison of the analytical model and experimental results has shown a reasonable agreement.

Volume 10, Issue 3 (12-2010)
Abstract

In this paper, a theoretical formula is derived to predict the instantaneous folding force of a single-cell square column under axial loading. Calculation is based on analys of “Basic Folding Mechanism” introduced by Wierzbicki and Abramowicz to calculate the instantaneous folding force. For this purpose, three mechanisms of energy dissipation were assumed. The formula obtained in this paper, can predicts the instantaneous folding force variations versus folding distance and versus folding angle with good precision and can predict folding force in each time instance instead of the average value. The results of theoretical formula were compared with experimental data and good agreement was observed. Keywords: Instantaneous Force, Folding, Honeycomb, Square Column.

Volume 13, Issue 6 (9-2013)
Abstract

In this paper, the role of isotropic and kinematic hardening models are discussed in cold forming of a U-channel considering the springback phenomenon. The effect of influential parameters on the springback is also studied. For this purpose, a cold roll forming machine was built using a milling machine. The effects of forming angle’s changes, sheet material, roll geometry and sheet thickness are studied experimentally and numerically. The results show that the isotropic work hardening model is more precise in prediction of the springback. 304 stainless steel and AISI 1015 are used in experimental verification. Comparison of the simulation results with experimental values demonstrates the accuracy of the modeling.

Volume 14, Issue 2 (5-2014)
Abstract

Forming limit diagram (FLD) shows the formability of metal sheets under different loading conditions before that necking is taken place. In this paper, the application of plastic instability criterion for prediction of necking and also FLD has been investigated. Using Balart’s anisotropic yield function and plastic instability criterion in different strain ratios, limit strains have been calculated, and then the limit strains have been converted to limit stresses. To verify the analytical results, a free bulge setup with the ability of applying the axial feeding has been fabricated. Tubes have been undergone different loading paths and different plane strain conditions have been induced to obtain FLD. FLDs which have been obtained using plastic instability criterion have been compared with experimental results. The results show that swift instability criterion for tubes have the best prediction of FLD in tube hydroforming process.

Volume 14, Issue 6 (9-2014)
Abstract

Flexible roll forming is a modern process for producing profiles with changing cross section. One of the important defects in this process is the web warping of product that causes failure to obtain dimensional and geometrical tolerances. In this paper, mechanism of web warping occurrence was investigated by finite element simulation in ABAQUS/CAE software. Results of simulation indicated that inadequate longitudinal strain in the edge of profile’s flange in transition zone is the reason of profile’s web warping. Furthermore, the effect of geometric parameters of product such as flange length, bend angle, radius of transition zone and thickness on the web warping were determined. Analysis of variance showed flange length and bend angle are recognized as the most effective factors on warping of profiles with specific thickness. An equation for prediction of warping was proposed in terms of geometrical parameters of product. In order to verify the finite element model, the longitudinal strain of deformed strip edge was obtained from simulations and compared with the experimental results of other researchers. A good agreement between them confirmed the accuracy of the finite element model.

Volume 14, Issue 8 (11-2014)
Abstract

Laser Forming (LF) process is one of the thermal forming processes; which uses laser beam irradiation as a forming factor. In this process, temperature gradient along the sheet thickness produces the final bending angle. So far, various investigations are carried out on laser forming of low carbon steel sheets. However, LF process can be utilised in other metallic and non-metallic sheets. High surface reflectivity and thermal conductivity of aluminium sheets, compared to steel sheets, make them more difficult and more complicated to be laser formed than that of steel sheets. In this Article, using LF process simulation with the finite element software, effects of several process parameters such as laser power, scan speed, laser beam diameter and sheet thickness on final bending angle are investigated. Numerical results are validated with the same parameter assigned experimental results. This comparison shows a very good accordance between simulation and experimental results. Also, an equation is derived to predict the final bending angle correspond to the variations of mentioned parameters. This is derived by the use of Design of Experiment (DOE) and full factorial approach.

Volume 14, Issue 16 (Forth Special Issue 2015)
Abstract

Prediction of critical process parameters which causes bursting and its location in warm tube hydroforming is a key factor in hydroforming parts design. In this paper, ductile fracture criteria have been modified so that effect of variation of temperature and strain rate on fracture is considered in forming of aluminum AA6063 tubes. Calibration of modified ductile fracture criteria has been performed using uniaxial tension tests at different temperatures and strain rates. Also, fracture strain and fracture work have been obtained as functions of Zener-Holloman parameter. Tube hydroforming process of a square part has been simulated at high temperatures in Abaqus software and loading curves with various axial feeds have been used to deform the tube. Then, the formed corner radius before bursting has been predicted using modified fracture criteria. A subroutine has been written for using modified fracture criteria. A warm tube hydroforming setup has been fabricated and prediction of modified ductile fracture criteria is compared with experimental results at various temperatures. Results show that modified criteria determine the location of bursting well. Maximum of thinning occurs in transition zone which the tube loses its contact with die cavity. Also, modified Ayada criterion, rather than other criteria, predicts corner radius with little error at high temperatures. Thus, because of its precise prediction, modified Ayada criterion can be used to predict the bursting of aluminum tubes at elevated temperatures.

Volume 15, Issue 7 (9-2015)
Abstract

One of the most important issues in the review of cold roll forming process of metals is estimation of required torque. The optimum production line can be designed by determining the effective parameters on torque. Some of these parameters are sheet material and thickness, bending angle, lubrication conditions, rolls rotational speed and distance of the stands. The aim of this study is to predict amount of required torque considering the factors influencing torque, including thickness, yield strength, sheet width and forming angle using artificial neural network. So the forming process was 3D simulated in a finite element code. Simulation results showed that with increase of yield strength, thickness and forming angle, applied torque on rolls will increase. Also the increase in sheet width -assuming constant web length- will decrease the torque needed for forming. The effects of thickness and sheet width were experimentally investigated which verified the results obtained by finite element analysis. A feed-forward back-propagation neural network was created. The comparison between the experimental results and ANN results showed that the trained network could predict the required torque adequately.

Volume 15, Issue 11 (1-2016)
Abstract

In this paper, the effect of processing temperature on the elastic and viscoelastic properties including storage modulus, loss modulus and damping value of PVC/plain weave fiberglass composites laminates was investigated. For this, composite samples with [0/90]10 lay ups were produced in three different temperatures including 160 ᵒC, 200 ᵒC and 230 ᵒC using film stacking procedure. Firstly, the flexural strength and modulus of the samples were measured using three points bending test according to ASTM D790-07 standard. Then, viscoelastic properties of the samples were measured in the temperature range of 25 ᵒC up to 220 ᵒC using Dynamic Mechanical Thermal Analysis (DMTA) and the effect of temperature on the viscoelastic properties was studied. Also, the effect of fiber/ matrix impregnation quality on the thermal and dynamic properties of the samples was evaluated using optical microscope images. It was concluded that the temperature of 230 ᵒC is proper to achieve high quality impregnation, according to both DMTA and three points bending test. Also, it was seen that increase of processing temperature up to 230 ᵒC increases the storage modulus; however, processing temperature doesn’t affect the glass transition temperature of the samples.

Volume 15, Issue 12 (2-2016)
Abstract

In recent years, aluminum, magnesium and titanium alloys are highly regarded in the aerospace and automotive industries due to their high strength to weight ratio and resistance to corrosion. The main problem of the use of these alloys is their low formability at room temperature. To solve this problem, the metal forming process is done at high temperatures. Since oil’s heat resistant temperature is not more than 300°c, other fluids such as air and nitrogen gas should be used in high temperatures. In this study, blow forming equipment at high temperatures has developed, and changing of AL6063 tubes cross-section from circular to square has investigated experimentally and compared with the results of the experiments at room temperature. After producing square products, thickness distribution, corner’s radius, forming pressure, and effect of pressure time in corner’s radius at different temperatures were compared and the location of bursting was also examined. The results indicated that by increasing temperature, formed radius and pressure time reduces significantly, so that the amount of radius decreases from 19.5 mm in the temperature of 25°c and 154 bar forming pressure, to 5.8 mm in the temperature of 500°c at 11 bar forming pressure. The results showed that by increasing time pressure, which causes to decrease velocity of process, the formed corners has been sharper. By investigating burst of specimens, bursting occurs in the area of converting circular cross section to square one, which has a high deformation and tensile strain.

Volume 16, Issue 9 (11-2016)
Abstract

Due to the polar functional groups of PVC thermoplastic and its good adhesiveness to the metals, production and roll forming of PVC/ aluminuim/ glass fiber FMLs were investigated in this research. At the first, flexural strength and bonding quality between PVC matrix and aluminuim layer in the FMLs were studied by doing three point bending tests according to ASTM D790 standard. In the following, FMLs with dimension of 12×80 cm and two layups including [0/90, 0/90, Al]s and [45/-45, 45/-45, Al]s were produced using film stacking and hot pressing procedure. The FMLs were rollformed into 30, 45 and 60º channel section profiles at 160ᵒC using a single stand rollforming process and geometrical decects including profile bowing, edge wrinkling, spring back and also aluminuim/composite layers delamination of the resulted profiles were evaluated. The FMLs also were roll formed into 86º channel section profiles using a multi stand roll forming process and the effects of multi stand roll forming on the defects stacking were evaluated. Finally, it was concluded that more than 45º bend angle increase in a rollforming stand results in composite/ aluminum delamination. Also, placement of the reinforcing fibers in the longitudinal direction of the profiles reduces the profile bowing and edge wrinkling defects significantly.

Volume 16, Issue 10 (1-2017)
Abstract

Hot metal gas forming is a process to form metals with low formability or high strength at room temperature such as aluminum, magnesium and titanium. With increasing temperature, the formability of these metals increases and the strength decreases. In this process, for producing parts with desirable properties, determination of optimal parameters is essential. In this study, hot metal gas forming process was simulated by using Abaqus software, and the influences of input parameters on the outputs were evaluated with simulation results. In order to validation of simulation results, the experimental test was carried out by using hot metal gas forming setup. For modeling hot metal gas forming process, an artificial neural network in Matlab software were trained by using data obtained from the numerical simulation. In this neural network, pressure, axial feeding and time were assumed as input parameters and the radius, minimum and maximum thickness were considered as output. In the next stage, this model was implemented as input function in multi-objective genetic optimization algorithm to obtain Pareto front and the optimum process parameters. Obtained optimum parameters include: pressure 13.07bar, axial feeding 0.78mm and time 65.73s and the values of corner radius, minimum and maximum thickness obtained from the optimum parameters are 5.49mm, 0.92mm and 1.57mm respectively.

Volume 16, Issue 12 (2-2017)
Abstract

In this paper, the effect of high frequency induction welding parameters on the weld quality of welded pipes is studied. In this purpose, process parameters such as current, frequency and edge shape of the weld connection and their effects on the heat distribution are investigated. Experimental investigation is performed by using tensile test, metallography, and micro hardness. This reveals three regions with different grading and various thermo-mechanical treatments. The results show that the grain size decreases about 27 percents as the edge shape is improved. By conducting thermo-magnetic analysis, different current intensities and frequencies are evaluated in the creation of appropriate temperature distribution. The results show that with increasing the current and frequency, the heat-affected zone is expanded and other areas become smaller. The maximum increase of the average temperature in the weld edge, was about 42 percents from 1250 to 1500 amperes per unit increase of the frequency. Micro-hardness test is used to detect micro-structural phases of the weld zone.By comparing the results of the metallography and micro-hardness tests, more uniform weld width was observed with modified edge of the in welded samples. The results represent 18 percents of decrease in the weld width of the modified samples in comparison with samples without edge preparation.

Volume 17, Issue 2 (3-2015)
Abstract

Caviar is one of the valuable and most popular fish products all over the world that are obtained from sturgeons. Nowadays, the wild resources of these fishes are diminished, therefore, to meet the demand for the product, farming sturgeons has been considered. The chemical composition and the amino acids profiles of the wild and farmed roe obtained from beluga (Huso huso) were compared and the results have indicated that the amount of glutamine, serine, alanine, methionine, and lysine in the wild roe were higher than the farmed one (P< 0.05). The total amino acids (TAAs) and the ratio of essential amino acids (EAAs) to TAAs and EAAs to non-essential amino acids (N-EAAs) in the samples from the wild and farmed roe were similar (P> 0.05). The protein efficiency ratio (PER) and chemical score in farmed and wild roe were also similar (P> 0.05). The results showed that the farmed roe was similar to the wild one based on chemical composition, chemical score, PER, EAAs/TAAs and EAAs/N-EAAs. According to the results, farmed roe can be a good substitution for wild beluga roe (Huso huso).

Volume 17, Issue 10 (1-2018)
Abstract

In this paper, cold roll forming process of a high strength steel pipe using four types of flower pattern including circular, edge, double radius and reverse bending is simulated with finite element method in MSC Marc Mentat software. Due to importance of quality of final pipe and in order to achieve the desired geometry in high strength steel pipes, selecting the appropriate flower pattern to design the pipe roll forming production line is considered. Using finite element simulation results, deformation of sheet in this process is studied and effect of flower pattern type on geometry of final product, which includes curvature distribution, spring back and thickness distribution of pipe, is investigated. Results show that implementing reverse bending flower pattern, leads to reduction in deviation from mean curvature at edge of the sheet up to about 65 percent. Thickness distribution analysis shows that circular and edge flower patterns cause upsetting and thinning of edge of the sheet up to 0.2 millimeters, respectively. But, use of double radius and reverse bending patterns cause average thickness of edge to be well adjusted to reach 2.8 millimeters. Also, circular flower pattern has the lowest value of spring back in terms of variation of mean relative curvature of 0.69 percent and edge deviation of 0.15 millimeters. To validate the finite element simulation, experimental tests were designed and conducted using one forming stand. By comparing resultant data of experimental tests with simulation results, validity of finite element simulation confirmed.

Volume 18, Issue 9 (12-2018)
Abstract

In this paper, considering the increasing need for high strength and thin pipes in the oil and gas industries, the effects of material strength and the initial thickness of the pipe and the friction between the pipe and the roller, on the distribution of the thickness and ovality of the cross-section of pipe in the process of sizing have been numerically and experimentally investigated. The simulation is performed using the commercial software MSC Marc Mentat. Results of the simulation show that by increasing strength material and reduction of thickness, the ovality of the cross-section of pipe decrease. It has been shown that with a 2.77-fold increase in the yield strength of a pipe with thickness of 2.8 mm, the ovality decreased by 27%. By decreasing the thickness of the St37 pipe from 2.8 to 1.8 mm, the ovality decreased to 2%. These changes increase with increasing yield strength, so that in the alform700 pipe with a thickness reduction of 2.8 to 1.8 mm, the ovality decreased to 45%. Furthermore, the friction condition has very little effect on the ovality of pipe. The validity of the finite element simulation is confirmed by comparison with experimental results.


Volume 19, Issue 5 (May 2019)
Abstract

Penetration into ceramic-aluminum targets is of prime importance for researchers in defense and non-defense industries. In this study, the effect of a blunt projectile having a specified speed and penetrating into a ceramic-aluminum target at angles of 0, 15, 30, and 45 degrees is investigated. In this research, 8 experiments were carried out at Ballistic Laboratory of Imam Hossein University and the design of the experiments was carried out in such a way that the facilities of the laboratory could be used. The results of the study showed that by increasing the angle of obliquity, is decreased substantially in ceramic-aluminum target, and when the angle of obliquity is increased beyond a certain limit, will ricochet. Also, in this study, numerical investigation was performed, using Autodyne software. In this numerical simulation, the impact of the blunt projectile at 700 m/s on ceramic-aluminum target was carried out to determine the penetration depth into the given target. The blunt projectile penetration was simulated with oblique carbide plates supplemented with aluminum 2024-T3 and the residual velocity and mass values of the projectile were determined at the exit of the combined target. The projectile was assumed to be rigid and the Johnson–Holmquist structural model was used to describe ceramic behavior and Johnson-Cook material model was used for projectile and target. The results of the experiments and numerical simulation were compared and there was a good agreement between these two modes of investigations, indicating the validity and accuracy of simulation assumptions.
 



Volume 19, Issue 133 (February 2023)
Abstract

Corn and soybeans have the largest area of ​​GM crops in the world. Milk powder and baby food are processed foods that contain corn and soybeans. Therefore, tracking transgenic corn and soy in processed food is one of the research problems. First, 40 samples of baby food and milk powder were collected from pharmacies and supermarkets in Tehran. All the samples were extracted using Azmaelixir DNA kit, and the nucleic acid concentration was checked with a nanodrop device, and internal control genes for soy (Lectin) and corn (Zein) were checked to ensure the extraction. Then, the presence of CaMV35S transgenic gene was checked by Real-time PCR technique. The results showed the presence of transgenic genes in 2.5% of baby food samples and 10% of samples in infant formula. Therefore, in this article, the amount of transgenic gene penetration in baby food and infant formula has been investigated.
 

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