فهرست مطالب

  • Volume:11 Issue:1, 2018
  • تاریخ انتشار: 1397/10/05
  • تعداد عناوین: 5
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  • Mohammaadhossein Zeinaddini, Mostafa Pirmoradian *, Farhad Azimifar Pages 5-13
    The aim of this study is to employ the novel Adaptive Network-based Fuzzy Inference System to optimize the torque applied on the knee link of a rehabilitation robot. Given the special conditions of stroke or spinal cord injury patients, devices with minimum error are required for performing the rehabilitation exercises. After examining the anthropometric data tables of human body, parameters such as the length of shins, weight, force, joint angle etc. were chosen as the input data with the torque as the output of the system. Errors at any stage of the treatment can harm the patient or disrupt their recovery. Therefore, after examining different numbers of various fuzzy inference system membership functions and their consequent error, cases with the lowest error were chosen to be the best possible conditions for the system. Overall it can be said that a robot using the adaptive network-based fuzzy inference system offers negligible error.
    Keywords: Rehabilitation, Adaptive Network-based Fuzzy Inference System (ANFIS), Fuzzy logic, Anthropometry
  • Mahyar Geibollahi, Ata Jahangir Moshayedi* Pages 15-21
    in the past decade, paying attention to the vertical fliers has been noted by most of the scientist and researchers, because of their exclusive features. The special capabilities of these, reducing radar identifier, low risk for human life, no restrictions on size and uses such as photography, survey, press coverage, checking, power lines, meteorological analysis, traffic, monitoring, in urban areas, crops and poison, spraying products, controlling country boundaries, controlling illegal imports and exports, fire detection and control, search and rescue operations for missing people and natural disasters can be mentioned, which leads to the plenty of motives for researchers. Contains wide researchers and putting various topics in front of researchers. One of these fields is using various algorithms with the ability to use in their control system. Mainly, the PID controllers are reported by the researchers, but although the PID controller as a classic model has some restrictions, it has shown a good performance. In this research, with the aim of design and implement of extracted value from the Dynamic system to controller point of view first, the history of vertical fliers and quadrotor are discussed, in the following, the result of PID controller is implemented on a real robot and its sustainability is investigated then, through applying the route to the quadrotor, the controller performance of stability and chasing the path is evaluated in practice.
    Keywords: robot, Quadrotor, PID Controller, Unmanned Flier, UAV (unmanned aerial vehicle)
  • * Nima Ghiasi Tabari, Saeed Mahdiyeh Borojeni Pages 23-33
    Landing gear is a structure that is mounted under the fuselage and helps the aircraft in takeoffs and landings. The most important duty of landing gear is the control of vibration exerted on the system through the shock absorber which is a common component to all the landing gear. Considering the importance of this issue, the necessity of investigating shock absorber with features such as high efficiency, reliability and maintenance, etc. is undeniable. In the present study In addition to choosing hydro pneumatic shock absorber its relationships arising from oil and gas liquids have been studied. This research was conducted with the aim of reducing the force variations and vibrations, with a focus on liquid gas. Thus, according to the gas laws, initially gas flow in the case of practical modes of isotherms during the taxi and poly trophic during landing has been studied. Considering that in the shock absorber only one mode can be used and Isotherms mode despite less vibration is not responsible for the landing phase and poly trophic mode exerts a lot of vibration on the fuselage, therefore a situation that can meet both needs in a way that have both phases of taxing and landing and at the same time reducing vibrations to be followed is the combination mode that its relation has been extracted at the end. The results of the extracted relations using numerical methods compared with practical results shows that not only the force on the aircraft body but also the vibrations on it have been significantly reduced and improves system performance.
    Keywords: landing gear, shock absorber, hydro pneumatic shock absorber
  • Mahsa Mokhtarian, Azam Gasemi* Pages 35-57
    This study aimed to evaluate Laser-cutting process of Mild Steel St37 sheets with two different thicknesses. In order to evaluate the quality of cutting edge and the depth of the area affected by the heat, several tests were conducted to determine the effect of parameters such as Laser power, Laser beam movement speed and pressure of axillary gas on the quality of cutting edge and the depth of the area affected by the heat. The results showed that three main parameters of Laser beam movement speed, the pressure of axillary gas and Laser power can affect surface roughness and depth of the area affected by the heat. The value for each of these main parameters should be optimized based on other parameters and in a predetermined range in order to reach optimal conditions and edge quality and to use the interaction of these parameters to determine the final optimal conditions.
    Keywords: Laser-cutting, Steel sheet, Quality of cutting edge, Finite elements
  • Hojat Ashori * Pages 59-72

    Loading conditions and complex geometry have led the exhaust manifolds heads to become the most challenging parts of diesel engines. Thermal fatigue failure of the engine components easily happens due to excessive temperature gradient and thermal stress. Modern exhaust systems must withstand severe cyclic mechanical and thermal loads throughout the whole life cycle. This study focuses on the Thermo-mechanical Fatigue (TMF) analysis for exhaust manifolds. The three-dimensional model of the exhaust manifolds was simulated in abaqus software and a chaboche model was utilized to investigate the elastic and plastic behavior of the exhaust manifolds. The numerical results showed that the temperature and thermal stresses have the most critical values at the confluence region of the exhaust manifolds. This area was under the cyclic tensile and compressive stress and then is under low cycle fatigue. After several cycles the fatigue cracks will appear in this region.The lifetime of this part can be determined through finite element analysis instead of experimental tests.

    Keywords: thermo-mechanical fatigue, Finite element analysis, exhaust manifolds, confluence cracks