Design and Implementation of a Simulating, pre-Analyzing and Processing System of Celestial Observations for Automatic Attitude, Azimuth and Local Position Determination of Movable Platforms
Farhad
Samadzadegan
عضو هیات علمی / پردیس دانشکدههای فنی، دانشگاه تهران
author
Masoomeh
Hamidi
دانشجوی کارشناسی ارشد / پردیس دانشکدههای فنی، دانشگاه تهران
author
text
article
2014
per
Star trackers as an example of celestial based sensors are specifically designed to perform accurate and absolute attitude determination. This requires us to measure the camera optical axis with respect to the local direction of the gravity and to have knowledge of time. This paper modifies the standard algorithms are implemented in star trackers so that they can estimate the local coordinates of the platform as well as the azimuth along with attitude data using observations from an accurate tilt meter and a clock. In order to validate our proposed method, different tests have been performed using developed simulator system. Results of the research described that proposed method has the capability of implementing in navigation purposes as an efficient alternative for GPS when it is not available and also periodic augmentation of Inertial Navigation Systems.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
3
v.
1
no.
2014
3
16
http://www.astjournal.ir/article_11494_a8d2c086f0be1a70c0d6be47239a3a09.pdf
Optimal Motion Cueing Algorithm Development of 6dof Flight Simulator Considering Workspace of Motion Platform
Amir
Sayadi
کارشناس ارشد / دانشکده مکاترونیک، دانشگاه آزاد اسلامی، واحد کرج
author
Abolfath
Nikranjbar
عضو هیات علمی / دانشکده مکاترونیک، دانشگاه آزاد اسلامی، واحد کرج
author
Ali
Mahmoodi
عضو هیات علمی / دانشکده مهندسی مکانیک و هوافضا، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات
author
text
article
2014
per
Skilled pilot training in aviation industry is of great importance. This in real terms due to high costs and safety considerations, is facing with serious obstacles. Thus providing low cost, efficient and repeatable flight training conditions attracted a broad range of researches. Flight simulators are such devices for training the skilled pilots. These tools aim to provide the same feeling of real flying for pilots, and give the opportunity to pilot to react under terms of the flight conditions. Motion cueing design algorithm is of the salient challenges in the design of these devices. The algorithm receives the linear acceleration and angular velocity of the real flight as the inputs and is due to calculate the appropriate movements of the actuators such that the infinite plane motions to get constricted to finite motions in the limited work space of the flight simulator. This has to be done in a way that the pilot in flight simulator feels as could as the same sense of motion of the pilot in aircraft. The authors aim to develop an optimal motion cueing algorithm for 6 DoF flight simulator with fuzzy compensated system specially focusing on the maximum use of workspace of the simulator to obtain more appropriate sense of motion. Comparing the results of the proposed fuzzy compensated and the conventional optimal motion cueing algorithms, shows an evident improvements in terms of smaller movements of actuators while achieving more appropriate motions of the flight simulator.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
3
v.
1
no.
2014
17
28
http://www.astjournal.ir/article_11495_7388375d09a6d18ee661bc1eafa014b6.pdf
Nalytical Prediction of Plastic Collapse of Conical Shell under Static Internal Pressure
Jamal
Zamani
عضو هیات علمی / دانشکده مهندسی مکانیک، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Mohammad Hossein
Benvidi
کارشناس ارشد / دانشکده مهندسی مکانیک، دانشگاه صنعتی امیرکبیر
author
Mehdi
Aghaei
کارشناس ارشد / دانشکده مهندسی مکانیک، دانشگاه صنعتی امیرکبیر
author
mohammad Vahab
Mousavi
کارشناس ارشد / دانشکده مهندسی مکانیک، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
text
article
2014
per
In this paper, plastic behavior of thin-walled conical shell under static internal pressure has been investigated analytically. In order to simplification, stress resultant along the slant of cone has been neglected and rigid-perfectly plastic model is used for material behavior. Common rectangular surface has been used as yielding criterion. According to present approach, cones are categorized into "long" and "short" based on their geometry. For each case, required pressure for initiation of plastic flow is formulated and is named collapse pressure. Maximum collapse pressure occurs at specific angle. The results coincide with collapse pressures of cylinder and circular plate at angels near 0º and 90º, respectively. The results have been depicted for various ratios of the larger radius of cone to the thickness. The differences between long and short cone have been distinguished.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
3
v.
1
no.
2014
29
36
http://www.astjournal.ir/article_11496_bb7e783a233dc244d3c2c44f0af80390.pdf
Present of Analytical Solution for Free Vibration of the Curved Thick Sandwich Beam with Flexible Core Using Higher Order Theory and the Dynamic Stiffness Method
Karamat
Malekzadeh Fard
عضو هیات علمی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
text
article
2014
per
In this paper, free vibration of the thick sandwich beams with flexible cores is investigated using the dynamic stiffness method and a new higher order theory. First the governing partial differential equations of motion for one element are derived using Hamilton’s principle. Closed form analytical solution of these equations is determined. After applying the effect of boundary condition of the element on the obtained equations, the element dynamic stiffness matrix is developed. These matrices are assembled and the boundary conditions of the beam are applied, so that the dynamic stiffness matrix of the beam is derived. Natural frequencies and mode shapes are computed by the use of numerical techniques and the well-known Wittrick–Williams algorithm. Finally, some numerical examples are discussed using the dynamic stiffness method and the analytical formulation. For verification of the present model, the obtained results are compared with the latest exact analytical and approximate finite element results.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
3
v.
1
no.
2014
37
48
http://www.astjournal.ir/article_11497_f22f90857c07ba5e0144cbf2948d93ee.pdf
Simulation of Strap-On Boosters Separation in the Dense Atmosphere
Mostafa
Jafari
کارشناسی ارشد / دانشگاه شهید بهشتی، دانشکده فناوری های نوین
author
Ali Reza
Toloei
عضو هیات علمی / دانشگاه شهید بهشتی، دانشکده فناوری های نوین
author
Sajad
ghasemlu
عضو هیات علمی / دانشگاه صنعتی مالک اشتر، مجتمع دانشگاهی هوافضا
author
Hamid
Parhizkar
عضو هیات علمی / دانشگاه صنعتی مالک اشتر، مجتمع دانشگاهی هوافضا
author
text
article
2014
per
A numerical dynamic-aerodynamic interface code for the separation dynamics simulation of constrained strap-on boosters jettisoned in the atmosphere is presented. This code includes a main environment which connects both dynamic and aerodynamic subsystems together at one time. The first part, consists of a 6-DOF multi body dynamic solver and the second part, contains a numerical aerodynamic flow solver, which is automatically used the dynamic mesh updating algorithm for adaption of the body motion in the discrete computational field. The relationship between dynamic and aerodynamic solver is such that the resultant separation software, can simulates multi body separation with complete mechanisms such as springs separation, Thrusters, joints, etc, in the presence of the aerodynamic effects. The flow solver is validated by the Titan-IV launch vehicle experimental data. After all, this method is used in simulation of strap-on booster separation for a typical launch vehicle with use of spring separation system and constraint joints in presence of aerodynamic effects and without them. Hence the aim of presented interface is to facilitate integration of complicated separation mechanisms simulation with a full numerical CFD aerodynamic solver.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
3
v.
1
no.
2014
49
60
http://www.astjournal.ir/article_11498_d5710b632e903f8179329e86bf8f0153.pdf
Porous Media Applications in Shock Attenuation on Suction side of an Airfoil
Mehdi
Yadegari
دانشجوی کارشناسی ارشد / پژوهشگاه فضایی ایران، پژوهشکده سامانه های فضانوردی
author
Seyed Arash
Seyed ShamsTaleghani
عضو هیات علمی / پژوهشگاه فضایی ایران، پژوهشکده سامانه های فضانوردی
author
text
article
2014
per
Shock formation on the surface of flying objects due flow compressibility and its interaction with boundary layer cause undesirable effects such as drag increment and flow separation. Various methods for reducing the effects have been suggested in the past like vortex generators, suction & blowing, and etc. This paper investigates numerically using of porous media for flow control and decreasing the shock effects. Porous media by increasing flow cross section and by combination suction & blowing reduces these undesirable effects. The numerical method is finite volume, the equations are Navier-Stokes and the geometric model is NACA0012 airfoil. The flow is assumed to be turbulent and steady in transonic regime. In addition, the geometrical modeling of porous media is validated in this paper. Results show that by decreasing the shock wave effects and consequently wave drag decrement, total drag coefficient decrease 20% and 16% using porous surface and porous media, respectively. The weaken shock is moved to the upstream and Mach number behind the shock decrease from 1.34 to 1.29. By decreasing the shock-boundary layer interaction effects, separation bubble is postponed from 0.58 to 0.78 chord length.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
3
v.
1
no.
2014
61
71
http://www.astjournal.ir/article_11499_9264eddb6720576914574f40384b5439.pdf
Investigation of Fin Span Effect on Performance of Missile on its Aerodynamics Analysis
Mehran
Nosratollahi
عضو هیات علمی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
Mehdi
Hashem Abadi
دانشجوی دکتری / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
text
article
2014
per
In this paper, the main goals are investigation of missile with grid fins, determination of aerodynamics coefficient and calculation of fin span effects on performance of missile. We solved Navier-Stokes equations for achieving of them. Nowadays, with improvement of numerical algorithms and speeding up of computers processors, CFD is one of the most convenient and high accuracy methods for analysis. The first, we introduce the grid fins and then analyze a fin with different span to investigation of fin span effect on performance of missile. Finally, we mount two grid fins on missile body and carry out CFD calculations on total missile at different Mach and angle of attack to compute the flow field and aerodynamics coefficient for a missile with grid fins. The results have been validated by comparing the computed aerodynamic coefficients for the missile and individual grid fins against wind tunnel measurement data. Very good agreement with the measured data was observed for all investigated configurations.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
3
v.
1
no.
2014
72
81
http://www.astjournal.ir/article_11500_bd1dcb9f18a627a39e886695b46179f0.pdf