TVET
S. Ghodrat; S. Shabestari; M. Malekan
Abstract
Eutectic Silicon phases form as the coarse and acicular shape in Aluminum-Silicon alloys. These phases have detrimental effect on mechanical properties of casting parts. Modification process has been used to change the shape of these phases to fibrous morphology. In this research different level of strontium; ...
Read More
Eutectic Silicon phases form as the coarse and acicular shape in Aluminum-Silicon alloys. These phases have detrimental effect on mechanical properties of casting parts. Modification process has been used to change the shape of these phases to fibrous morphology. In this research different level of strontium; in the form of Al-10%Sr master alloy; have been added to 319 aluminum alloy to investigate their effects on modification. Thermal Analysis has been used as a technique to study the cooling curves and first derivative curves. Effect of strontium on solidification parameters such as nucleation temperature ((, and growth temperature () of eutectic silicon has been determined. ((and () have been reduced by increasing strontium content. () can be used as a parameter to control the modification of eutectic silicon. The results of this research indicate that thermal analysis technique can be used as an accurate and quick device of on-line quality control in production lines of aluminum casting industries.
TVET
M. Hadi; A.R. Kamali; S.M.M. Hadavi
Abstract
In this study, effect of hot work on microstructure and mechanical properties of nickel based alloy NiAl8Cr8MoZrB (IC-221M) was investigated. For this purpose, four types of hot work processes at 1000 and 1100 °C with various apply strain were done. Also two types of two stage hot work processes ...
Read More
In this study, effect of hot work on microstructure and mechanical properties of nickel based alloy NiAl8Cr8MoZrB (IC-221M) was investigated. For this purpose, four types of hot work processes at 1000 and 1100 °C with various apply strain were done. Also two types of two stage hot work processes were performed. Our results show that low strain rate hot working causes to reduction of eutectic regions in the microstructure and ordering parameter of crystalline structure and increasing high temperature mechanical properties of as-cast alloy. Finally, two stage hot pressing process on the basis of dynamic recrystallization mechanism leads to increasing mechanical properties of alloy at 1000 °C.
TVET
A. Rezaei; S. Ahmadi; A. Shokouhfar
Abstract
In this research, dynamic recrystallization of an Al-Li alloy was investigated in two temperatures, i.e. 350°C and 400°C. Wedge samples were subjected to hot rolling deformation in high temperature and one passes. For wedge specimens, reduction up to 70% was considered. Results showed that grain ...
Read More
In this research, dynamic recrystallization of an Al-Li alloy was investigated in two temperatures, i.e. 350°C and 400°C. Wedge samples were subjected to hot rolling deformation in high temperature and one passes. For wedge specimens, reduction up to 70% was considered. Results showed that grain size of the specimens after hot rolling decreases from 100μm to 30μm because of dynamic recrystallization phenomenon. Furthermore, it is observed that critical reduction for starting dynamic recrystallization was 50% and 40% in 350°C and 400°C respectively.
TVET
M.S. Taher Tolou Del; S.B. Hosseini
Abstract
The Modern Architectural Monuments needs solidity (resistibility or Stability); fortunately (firmness or Durability); value ability (beatify or Permanency) for their sustainability. In all of five Architectural creation components; as: Form and mien, Technology and construction, environment and Function, ...
Read More
The Modern Architectural Monuments needs solidity (resistibility or Stability); fortunately (firmness or Durability); value ability (beatify or Permanency) for their sustainability. In all of five Architectural creation components; as: Form and mien, Technology and construction, environment and Function, Concept and aim; just the missed chain link in Architecture training program is the Unity and Integrity action component that would be solve real design by having the solidity, sufficiency, modality, vernacularism, with aesthetic direction requirements. In the other hand, Using the Conceptual, Formal, Skills, Technical and flexibility in Architectural design isn’t sufficient for an Architecture Monument. Thus we must use all of mention that has discussed at above in the integral and unique management manner stage that would be guide and supervised. In this paper by site work questions and traditional manner investigation, has tried to show the effect of role of unique and compatible training as the Main component of permanent Architecture. By this investigation would be lead us to all of these themes: Technique, Mien, Sufficiency and Theorize that must be contemporaneous with Unity and Compatibility for new creation of modern Architecture in this epoch.
TVET
A. Darabi; M. Saeedi; A. Hassan Nia Khobeiri; T. Ghanbari
Abstract
Embedded generation is a developed generation form in modern power systems. Many of embedded generators are working in parallel with the modern power networks. On the other hand, the power systems are designed based on centralized generation, not to work with embedded generators. Therefore, the embedded ...
Read More
Embedded generation is a developed generation form in modern power systems. Many of embedded generators are working in parallel with the modern power networks. On the other hand, the power systems are designed based on centralized generation, not to work with embedded generators. Therefore, the embedded generators may be lead to some control and protection problems in these systems. The embedded generator protection against loss of main network (LOM) is one of the most important of these problems. A practical protection procedure must be able to recognize the differences between the LOM and similar conditions such as load switching, ordinary faults, etc. In this paper, a new method based on synchronous generator sequence Impedances was developed that has an improved performance. The MATLAB/SIMULINK based system simulation shows the validity of the proposed method.
TVET
S. Ahmadi; A. Shokouh Far; M.R. Abutalebi; A. Rezaee
Abstract
Aluminum-lithium alloys are among the ultra-lightweight and workable alloys that have replaced some air alloys (such as 2000 and 7000 groups) due to their higher elastic modulus and lower specific gravity. Increasing the mechanical properties of these alloys using various thermal-mechanical methods (Thermo ...
Read More
Aluminum-lithium alloys are among the ultra-lightweight and workable alloys that have replaced some air alloys (such as 2000 and 7000 groups) due to their higher elastic modulus and lower specific gravity. Increasing the mechanical properties of these alloys using various thermal-mechanical methods (Thermo Mechanical) has always been considered by researchers. Creating GP regions through low temperature aging processes has a great impact on the physical and mechanical properties of aluminum-lithium alloys. In this research, in the first part of the experiments, by performing natural aging and artificial aging at a temperature of 100 اد C, the formation and impact of these areas on the properties of the alloy were investigated. In the second part of the experiments, the precipitation of phase T1 during the aging process and the effective effect on the optimal time of the aging process at temperatures C150 and C190 for a sample of aluminum-copper-copper-lithium alloy sheet have been investigated. The results show that the formation of GP areas in the structure increases the hardness, strength and special strength of the alloy and by performing the aging process at higher temperatures and forming stable sediments, the process of increasing the hardness and strength continues while the special strength of the alloy decreases. It was found that the change in energy level in the range C250 to C300 is related to the deposition of phase T1 and the change in energy level in the temperature range C450 to C305 due to its dissolution in the alloy structure. The energy of the formation and dissolution activations of phase T1 in this study was calculated to be (kj / mol) 1/122 and (/ mol (kj3 / 130), respectively, which is equal to the activation energy of the penetration of the constituent elements of this phase (copper and lithium) in the network structure. It is aluminum.
TVET
Z. Nasiri Gheydari; H. Lessani; A. Darabi; F. Totonchian
Abstract
The permanent magnet hysteresis motor has the advantages of both the hysteresis motor and the permanent magnet. This engine is ideal for applications for electric vehicles, compressor pumps, robots and precision industrial drives, such as inertial navigation systems and video recorders that require high-performance ...
Read More
The permanent magnet hysteresis motor has the advantages of both the hysteresis motor and the permanent magnet. This engine is ideal for applications for electric vehicles, compressor pumps, robots and precision industrial drives, such as inertial navigation systems and video recorders that require high-performance soft, low-performance, and high-performance audio. . In this article, we will model and simulate this engine. We first derive the dynamic equations of the engine by considering the Foucault effect, and then we present the equations of its state for simulation in the SIMULINK / MATLAB environment. Finally, we compare the results of the simulation with the results of the numerical method and the finite element. This comparison shows a good match for these results. The method presented in this paper is time-limited, faster than the finite element method, and has acceptable accuracy.
TVET
A.R Dourandish; G.H Paygane; S. Agha Najafi; G.H. Dehghan
Abstract
The purpose of this paper is to examine the design method of a micro-constraint that, with proper performance, can automatically take a micro-part according to the important parameters of the reaction time and force, and after performing various steps on the part. Be. Release the piece and be ready to ...
Read More
The purpose of this paper is to examine the design method of a micro-constraint that, with proper performance, can automatically take a micro-part according to the important parameters of the reaction time and force, and after performing various steps on the part. Be. Release the piece and be ready to take the next piece. The use of CMOS technology in the design of retaining walls and the use of SMA technology in the design of the retaining bracket and its replacement instead of other existing designs in optimizing energy consumption power and reaction time, as well as combining the last two technologies play an essential role in this article. Is responsible. In the following, the mentioned design is examined through stimulation modeling based on mass and spring system and using mathematical software, analytical equations of stimulus movement based on time are extracted so that the time of deformation of stimulus can be calculated as a parameter.
TVET
A. Afshar; M. Shafie; O. Bozorg hadad
Abstract
By building large dams in different countries of the world, increasing the efficiency and effectiveness of these reservoir systems and maximizing the benefits of them is one of the most important issues studied in recent years. Evolutionary algorithms such as genetic algorithms (GA) are used in many ...
Read More
By building large dams in different countries of the world, increasing the efficiency and effectiveness of these reservoir systems and maximizing the benefits of them is one of the most important issues studied in recent years. Evolutionary algorithms such as genetic algorithms (GA) are used in many scientific and engineering categories as search and optimization tools. Many applications of these methods have been reported on the issue of optimal utilization of reservoirs. In this research, an attempt is made to evaluate and evaluate the potential of new and applied formulations of genetic algorithm in solving engineering problems, to provide a new structure in order to optimize the operation of reservoirs using GA. In this study, new structures of the genetic algorithm are examined by performing different sensitivity analyzes and the best of them will be used to determine the optimal release of reservoir outflows. The results show that GA has the ability to provide good responses in the optimal use of reservoirs. Based on these results, the genetic algorithm with elitism, along with the two-point shear displacement operators and the low probability mutation, produces the best response. These results indicate the relatively good potential of genetic algorithms in solving large-scale problems that have complex objective functions.
TVET
H. Jafari
Abstract
Solution heat treatment followed by Quench and return is one of the important processes in the production of cast aluminum aluminum castings and significantly improves the microscopic structure and mechanical properties and changes the temperature of the fuzzy evolution in these alloys. In the present ...
Read More
Solution heat treatment followed by Quench and return is one of the important processes in the production of cast aluminum aluminum castings and significantly improves the microscopic structure and mechanical properties and changes the temperature of the fuzzy evolution in these alloys. In the present study, the effect of heat treatment on aluminum fatigue of cast bronze containing 11-10% aluminum, 4% nickel, 4% iron and 3% manganese was investigated. After production, the alloy has been subjected to thermal maintenance at temperatures of ◦700, 750, 800, 850 and 900 ، C for 20-30 minutes, quench in water, and finally return to ◦C600 ساعت C for 2 hours. The results of this study showed that aluminum casting bricks have a much higher fatigue rate than non-thermal cast aluminum alloys, and the highest fatigue level as well as hardness is obtained at ◦850 عملیات C. . The structure of the microscope and the images of the electron microscope obtained from the refractive surface of the cast and heat-treated specimens also confirm this.
TVET
A. Soltani
Abstract
The Kashmar granitoid (42.5 Ma) occurs in NE Central Iran Plate (CIP). It mainly includes felsic metaluminous (ASI ≤ 1) I–type granite and granodiorite plutons. Microprobe analyses show that the Kashmar amphiboles are low in Ti and (Na+K)A contents (all < 0.5 apfu), indicating magnesio–hornblende, ...
Read More
The Kashmar granitoid (42.5 Ma) occurs in NE Central Iran Plate (CIP). It mainly includes felsic metaluminous (ASI ≤ 1) I–type granite and granodiorite plutons. Microprobe analyses show that the Kashmar amphiboles are low in Ti and (Na+K)A contents (all < 0.5 apfu), indicating magnesio–hornblende, a distinct mafic mineral of low–temperature I–type granites. Also, the content of Al2O3 is low, suggesting low–pressure crystallization. The Mg* ratio is high (0.60–0.75) and the AlVI is extremely low (< 0.1 apfu), but Fe3+ is much higher than AlVI, features confirming low–pressure and low–temperature conditions. Utilizing the modern thermo–barometers, the pressures of ≤ 3 kb and average temperature of 655 oC were calculated for Kashmar amphiboles. The attributed log fO2 values are negative, ranging from –16.59 to –19.40 and plotting above the QFM stability. Results of this study propose a thermal boundary of ~700 oC between felsic (~600–700 oC) and mafic (~700–800 oC) low–temperature I–type granites, and reinforce the modern granite subdivision.
