Aerospace Science and Technology
Designing a Hybrid GEO-LEO Constellation Pattern for Regional Satellite Navigation in Iran

Shahrokh Zohrabzadeh Bozorgi; Abolghasem Naghash

Articles in Press, Accepted Manuscript, Available Online from 05 November 2022

https://doi.org/10.22034/jast.2022.362842.1132

Abstract
  In this paper, a few hybrid satellite constellations including combinations of LEO and GEO satellites for providing satellite navigation and positioning services for users in Iran have been designed and proposed. The performance of the constellations has been analyzed based on DOP values variations. ...  Read More

Aerospace Science and Technology
Improving the performance and work-absorbing capacity of the axial-flow compressor by using tandem blades.

Alireza Sekhavat Banis; Reza Aghaei Togh

Articles in Press, Accepted Manuscript, Available Online from 11 December 2022

https://doi.org/10.22034/jast.2022.357363.1126

Abstract
  The compressor blade is responsible for increasing the flow pressure. By adding a blade behind the main blade, the compressor performance can be improved by increasing the pressure ratio and reducing the weight. The tandem improves the performance and increases the compressor absorption coefficient by ...  Read More

Aerospace Science and Technology
Determination of a High-speed Centrifugal Pump's Stable Performance Range by Computational Fluid Dynamics

Ali Cheraghi; Reza Ebrahimi

Articles in Press, Accepted Manuscript, Available Online from 24 December 2022

https://doi.org/10.22034/jast.2022.357423.1128

Abstract
  Feed pumps play a crucial role in the dynamics of hydraulic systems. The surge phenomenon is a common type of instability in pumps and compressors. This phenomenon is a systematic instability and is influenced by the dynamics of all components of a hydraulic system, including tank, valves, suction pipes, ...  Read More

Aerospace Science and Technology
A Fuzzy Fast Terminal Approach for Tracking a Probe Around an Asteroid

Mahsa Azadmanesh; Jafar Roshanian; Mostafa Hassanalian

Articles in Press, Accepted Manuscript, Available Online from 31 December 2022

https://doi.org/10.22034/jast.2022.362213.1131

Abstract
  This paper employs the fast terminal sliding mode control with the sign and the saturation function to track the landing trajectory of a probe on an asteroid and to further improve the dynamic tracking performance. Then the controller is enhanced by adding the fuzzy control to both fast terminals. To ...  Read More

Aerospace Science and Technology
Different Intelligent Methods for Coefficient Tuning of Quadrotor Feedback-linearization Controller

Mana Ghanifar; Milad Kamzan; Morteza Tayefi

Articles in Press, Accepted Manuscript, Available Online from 18 January 2023

https://doi.org/10.22034/jast.2023.355914.1123

Abstract
  This paper investigates different intelligent methods of tuning feedback-linearization control coefficients. Feedback-linearization technique is an effective method of controlling nonlinear systems. The most critical part of designing this controller is tuning the gains, especially if the plant has complex ...  Read More

Aerospace Science and Technology
Numerical Study of the Effect of Tip Clearance and Rotor-Stator Distance on the Performance of an Axial Turbine

Amir Akbari; Hossein Khaleghi

Articles in Press, Accepted Manuscript, Available Online from 25 January 2023

https://doi.org/10.22034/jast.2023.295476.1098

Abstract
  The use of unshrouded turbine rotor blades can considerably reduce the weight of an aero engine. However, in an unshrouded high-pressure turbine, the tip leakage flow generates about 30% of the turbine total loss. Another factor which affects the loss in axial-flow turbines, is the axial distance between ...  Read More

Aerospace Science and Technology
Optimal Round Trip Path-Planning of An Aerial Robot by Consideration of Geometric Constraints of Obstacles

Shayan Dehkhoda; Mohammad-Ali Amiri Atashgah

Articles in Press, Accepted Manuscript, Available Online from 31 January 2023

https://doi.org/10.22034/jast.2023.326735.1112

Abstract
  This paper is dedicated to the optimal path-planning of a quadrotor to deliver the goods in the form of a round-trip mission. At first, quadrotor modeling is performed by the Newton-Euler method and then the problem is formulated as an optimal control effort problem. Then, by discretization of the equations ...  Read More