Showing 13 results for Edm
Volume 1, Issue 1 (4-2013)
Abstract
Comparative literature is a branch of literature that considers the literary relation and influences of the countries. Scholar of comparative literature sits between two or more branches and records the literary-cultural transfers. This article is an attempt to study the cultural and story similarities between two the literary works; an Iranian and a French. "Leili o Majnoun", Nezami’s literary work and "Cyrano de Bergerac", Rostand’s piece have commons aspects about the content and the personality of their heroes; platonic love is the most important element in these literary works. Among the other similarities, we can represent the reality of their stories and the common literary structure. In spite of the similarities, we should consider the differences of the heroes in their manner of love-affair. An innocent love is another common point between these masterpieces, which finished with the death of heroes, Majnoun and Cyrano. In this article, we try to expand these similarities and the differences with a comparative consideration in order to conquer a new horizon.
M. Ghoreishi, S. Assarzadeh,
Volume 6, Issue 1 (9-2006)
Abstract
The complex and stochastic nature of the electro-discharge machining (EDM) process has frustrated numerous attempts of physical modeling. In this paper two supervised neural networks, namely back propagation (BP), and radial basis function (RBF) have been used for modeling the process. The networks have three inputs of current (I), voltage (V) and period of pulses (T) as the independent process variables, and two outputs of material removal rate (MRR) and surface roughness (Ra) as performance characteristics. Experimental data, employed for training the networks and capabilities of the models in predicting the machining behavior have been verified. For comparison, quadratic regression model is also applied to estimate the outputs. The outputs obtained from neural and regression models are compared with experimental results, and the amounts of relative errors have been calculated. Based on these verification errors, it is shown that the radial basis function of neural network is superior in this particular case, and has the average errors of 8.11% and 5.73% in predicting MRR and Ra, respectively. Further analysis of machining process under different input conditions has been investigated and comparison results of modeling with theoretical considerations shows a good agreement, which also proves the feasibility and effectiveness of the adopted approach.
Volume 11, Issue 1 (1-2009)
Abstract
This research was performed to evaluate the potentials of Landsat MSS data for map-ping land features in arid zones of southeastern Esfahan, Iran. Databases of the area were formed using all available relevant maps and reports which were supported by fieldwork. A supervised image classification approach was used and thirty-two training areas were applied. Separability of the spectral classes was examined using feature space plots of im-agery data and self-classification of training areas. The accuracy of the classification was examined by using test and random pixels. The results show the potential of Landsat data for the discrimination of landforms and zones of the playas. Sand deposits (deflated sands and Barchans) expressed different spectral reflectance which could be due to mineralogy of these features. Soil classes differing in moisture content and salinity located on the soil line and limestone classes located along the soil line. The applied imagery data disable to discriminate Barchans from Bare soil I and Andesitic fans from Grey limestone. After image classification the spectral classes were merged to form landforms. The main land-forms were mountains, piedmonts, sand dunes, valleys and playas. The results indicate that integration of field observation and supervised classification can compensate for the lack of detailed topographic maps in some areas.
Jamshid Parvizian, Hamid Abyar, Amir Abdullah, E Gh,
Volume 13, Issue 7 (10-2013)
Abstract
Abstract: Wire electrical discharge machining (wire-EDM) has a significant position among production technologies mainly due to its capacity of machining hard materials and intricate shapes. One of the major problems with this process is the error in cutting corners. Processing forces acting on the wire and low rigidity of the wire are responsible for wire deformation, which has a direct influence on the accuracy of the corner cutting. In this research, investigation is focused on the convex corner radii errors and alternative solutions are proposed for the case of successive cuts (one roughing and two finishings). Experiments are carried out for roughing operation by considering frequency of discharges and feed speed. The residual materials on straight and curved paths are the output parameters. Results indicate that optimization of these parameters have a better influence for control of residual material thickness on straight paths than on curved corners. One important conclusion is that roughing is the most influential stage of cutting by WEDM. Then, concave corner radii produced during successive cuts, the effect of corner angle and corner radii are investigated. Errors at radii of different corner angles are identified and related to arc length and residual material thickness in the curved corner. Finally, an effective approach is presented for improving the accuracy of the small-radius concave corner radii of finishing stage. The main conclusion is that to achieve accurate corner radii, one must increase the traversed corner arc length by wire in the small-radius concave corner radii.
Ahad Gholipoor, Hamid Baseri, Mohsen Shakeri,
Volume 14, Issue 1 (4-2014)
Abstract
The near dry EDM process uses a mixture of a liquid and a gas as dielectric medium. In this study, near dry EDM process at three levels of discharge energy and with two brass and copper electrode was studied to investigate the effects of tool material on machining performance. Also, the Taguchi method of design of experiments technique was employed to study the effects of nonelectrical parameters such as tool rotational speed, liquid flow rate, gas pressure and also discharge energy on material removal rate (MRR), electrode wear ratio (TWR) and surface roughness (SR) and also the analysis of variance (ANOVA) was employed to find the most important factors effecting MRR, TWR and SR. The results showed that copper electrode has higher MRR and lower TWR as compared to brass electrode. Also the analysis of main effect plots obtained by Taguchi method indicated that MRR and SR is enhanced by increasing water flow rate and discharge energy and also increasing gas pressure leads to lower TWR. The ANOVA results showed that discharge energy is the most important factor influencing MRR, TWR and SR.
Majid Ghoreishi, Vahid Tahmasbi,
Volume 14, Issue 12 (3-2015)
Abstract
In this paper, dry electro-discharge machining (Dry EDM), one of the newest machining processes which differs mainly from conventional EDM in using gaseous dielectric along with tool electrode rotation, has been studied. Gap voltage, discharge current, pulse-on-time, pulse-off time, dielectric gas pressure, and electrode rotational speed have been considered as effective input parameters. Response surface methodology (RSM) has been used to optimize the machining performance with respect to material removal rate (MRR). Base on the results and analysis of running experiments, it can be concluded that MRR increases by increasing gap voltage, discharge current, the ratio of pulse-on time over pulse-off time, input gas pressure, and electrode rotational speed. There also exists an optimum amount of pulse-on time determined according to the machining circumstances. Also the material removal rate in dry EDM has been improved compared with that in conventional EDM in identical conditions. Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM) Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM) Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM)
Mohammad Reza Shabgard, Behnam Khosrozadeh,
Volume 16, Issue 2 (4-2016)
Abstract
Titanium alloy Ti-6Al-4V is one of the most used industrial alloys that is used often in important and risky applications. One of the requirements for machining such parts is to achieve the appropriate surface integrity. Powder mixed electrical discharge machining is a process which has different mechanism compared with traditional electrical discharge machining process; and it often used in order to obtain good surface finish. In this study two different kind of Nano powders SiO2 and Al2O3 added in dielectric for machining of Ti-6Al-4V titanium alloy; so that the effect of adding them on the output characteristics of the electric discharge process, including removal rate, tool wear ratio, surface roughness and integrity is investigated and compared. In order to investigate surface micro cracks and heat altered layer, surface and cross section of it were studied by scanning electron microscopy imaging. The results show addition of Nano powders into dielectric, especially SiO2, increases material removal rate, the effect of Nano powders on tool wear ratio depends on machining condition and setting. SiO2 Nano powder decreases surface roughness more than Al2O3 Nano powder. Surface integrity of machined sample in terms of micro-cracks and depth of the heat altered layer is improved with the addition of nanoparticles.
Mohammad Reza Shabgard, Behnam Khosrozadeh,
Volume 16, Issue 8 (10-2016)
Abstract
Electrical discharge machining is one of the usual and widely used machining processes for machining hard metals and alloys which has low machinability by traditional machining methods. Due to the thermoelectric nature of this process, changes in metallurgical and mechanical properties of machined surface and development of residual stresses in components are inevitable. In this research machining of Ti-6Al-4V titanium alloy is conducted by ultrasonic assisted electrical discharge machining process and the effects of ultrasonic vibration of tool on the machining efficiency, surface integrity such as surface micro-cracks, residual stress and surface hardness has been evaluated. Machined surface were imaged by scanning electron microscopy imaging to study the size and distribution of surface micro-cracks. Residual stresses along the depth of the machined surface, evaluated using Nano indentation technique and hardness of discharged surface is measured using a micro hardness measuring instrument. The results show that applying ultrasonic vibration increases electrical discharge machining process efficiency (about 90%), reduces the amount and size of surface micro-cracks, changes residual stress distribution and decreases the amount of it (average 17%); Increases of surface hardness caused by ultrasonic assisted electrical discharge machining process is 13% more than the traditional electrical discharge machining process.
Volume 18, Issue 3 (8-2018)
Abstract
The aim of this study is to investigate optimal monetary and fiscal policies for the Iranian economy considering Ramsey problem. Using a Dynamic Stochastic General Equilibrium model, the effects of imposing various taxes such as consumption tax, capital income tax, labor income tax and profit tax are examined by different scenarios. The results indicate that Friedman’s rule, or zero inflation is determined as optimal monetary policy under scenarios with and without price rigidities. In addition, since the governments try to minimize the distortions from taxes levied on different economic sectors, necessity of a subsidy or negative tax is confirmed under Ramsey conditions. According to the findings, the inflation rate not only depends on nominal and real rigidities assumed in the model, but also to the number of instruments available to the Ramsey planner.
H. Abyar Firouzabadi, A. Abdullah,
Volume 19, Issue 6 (6-2019)
Abstract
Wire Electrical Discharge Machining (WEDM) is known as an advanced manufacturing process, especially for producing delicate and intricate shapes and cutting difficult-to-cut materials. Machining error on is an important problem associated with this process. The current paper investigates experimentally the machining errors of three-stage WEDM on the small straight and arced paths. To reveal the reason behind these errors and to compensate them, residual materials of each cutting stage on the straight and arced corner paths were separately measured and analyzed. Machining errors of each WEDM stage in both paths were accurately considered and the causes of these errors in the straight and small arced paths were experimentally and theoretically determined and discussed. Experiments showed that the roughing stage has such a serious deteriorating influence the machining errors on the arced paths that it cannot be compensated in the following finishing stages. The spark angle domains of the roughing stage on the arced paths were calculated and the effects of these domains on the machining errors due to wire diversion from the programmed path were analyzed. In addition, this research proposes a novel guide in multi-stage WEDM by defining some machining concepts and developing equations for error calculation of WEDM finishing stages on these paths. The machining errors estimated by equations have consistency with the related experimental ones. of this study can be employed in the accurate WEDM cuttings.
S. Dinarvand, B. Jabbaripour,
Volume 20, Issue 7 (6-2020)
Abstract
Modern intermetallic compound of gamma titanium aluminide (γ-TiAl) due to its low density, high elastic modulus, high resistance to oxidation, corrosion, and ignition has recently been considered in the aerospace and automotive industries. Traditional machining of this alloy is so difficult. In the current study, electrical discharge machining of γ-TiAl samples is investigated using different tool electrodes of graphite, copper, and aluminum. The results show that when using aluminum electrodes, tool wear rate is averagely 3.2 times more than copper and 5.8 times more than graphite tools. In addition, when using graphite electrodes, the average material removal rate is 4.2 times more than copper and 7.7 times more than aluminum. Machining by aluminum tool leads to formation of Al2O3 and TiO2 oxide compounds on the work surface but in machining by graphite electrode, TiC and Ti8C5 carbide phases are created on the work surface. In machining by graphite due to formation of hard carbide compounds in the recast layer, the microhardness is higher than the machined sample by the aluminum tool, where oxide compounds exist on the surface and the hardness of recast layer in the machined sample by copper electrode is less than the other two electrodes, because of existing phases such as copper oxide with less hardness. The highest electrochemical corrosion resistance belongs to the machined specimen using graphite tool and the lowest corrosion resistance is related to the machined sample by aluminum electrode. Reducing oxide and aluminum compounds and increasing carbide phases enhance the corrosion resistance of γ-TiAl machined samples.
Volume 21, Issue 83 (4-2024)
Abstract
After Aristotle that was the first theorist of plot, in recent decades, Propp was the first theorist that start searching for common frameworks and patterns in the plot, especially in folktales; And these studies continued after him. Norman Friedman is one of the contemporary narratologists who has studied the structure of the plot, influenced by the methods and views of Aristotle and Propp; and based on the three main components of Aristotle's view, namely action/ fortune, character and thought, he has introduced 14 types of plots. Since structures and themes are generally repetitive in folk tales, in the present study, the types of plots in Nakhshabi's Touti Nameh stories, which are folk works of the 8th century, have been studied in a descriptive-analytical manner based on Friedman's view; While introducing a new perspective to narratology research, find out which one of the 14 types of plots is used in the Touti Nameh. Based on the results, in the 75 main and sub-stories examined, all types of Friedman plots are used, and this shows the richness and structural variety of the plot in this work; It was also found that there is a significant relationship between the use of some of the most frequent types of plots of fortune and character in stories.
Volume 24, Issue 2 (6-2024)
Abstract
In today’s society, pipelines as vital arteries play a significant role in maintaining people’s peace and satisfaction. According to growing developments in societies, the necessity of constructing, refurbishing, repairing, and maintaining underground installations such as petrol pipelines, gas, water, wastewater, runoffs, and connections is considered as the indispensable part of civil and installation operations. Regarding problems stemming from the open trench excavation methods and growth of underground installations, using trenchless technologies in the construction industry is increasing in order to solve the problems more economically and effectively. The present project aimed at recognizing and ranking the most important effective factors in accepting the trenchless technology in Iran. This research has a practical target and has been performed by the survey and the describing method. The statistical population of this research includes middle managers, contractors, and civil projects engineers of Isfahan province. In this regard, a sample of 87 people was randomly selected and the questionnaire was distributed among them. Eventually, a total of 68 questionnaires were collected with favorable consistency. This questionnaire has been designed by the investigator according to the Likert scale with high stability. Accordingly, the factors were grouped in the form of 28 criteria and 8 major groups as the effective factors on accepting the trenchless technology in Iran. Descriptive and inferential methods and the Friedman test were used to rank the effective factors, and the SPSS software was applied to analyze the data. Among the 8 major groups of executive management, environmental, demographics, technology, economically, project productivity (construction management), organizational, and individual had the first to the 8th rank, respectively. In addition, control system, risks, environment, budget, chief executive officer (CEO), special and geographical performance, and direct costs ranked the top among the 28 factors.
