Research Paper
Hasan Naseh
Volume 9, Issue 4 , April 2017, Pages 1-12
Abstract
The major purpose of this paper is to present Space Launch System (SLS) family technology development from propulsion system aspect. Thus, the models of cost estimation for two types of propulsion systems (cryogenic and semi-cryogenic) are derived based on the statistical method and are then compared ...
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The major purpose of this paper is to present Space Launch System (SLS) family technology development from propulsion system aspect. Thus, the models of cost estimation for two types of propulsion systems (cryogenic and semi-cryogenic) are derived based on the statistical method and are then compared with each other. The SLS family modernization model includes five main steps:(1) SLS family propulsion system mass and energetic calculations; (2) Cost estimation and analysis; (3) Sensitivity analysis of propellant volume tanks; (4) Sensitivity analysis of propulsion system performance based on cost; (5) mass, energetic and cost calculations of cryogenic and semi-cryogenic propulsion systems. Finally, the results of the modernization methodology execution are verified by an existing propulsion system.
Research Paper
Mojtaba Alavi pour; Amir Ali Nikkhah; Jafar Roshanian
Volume 9, Issue 4 , April 2017, Pages 13-25
Abstract
In this research, the problem of optimal trajectory design of an upper stage is considered for satellite injection into Geostationary orbit in 3-Dimensional space. The optimal multi-burn trajectory is obtained based on Euler-Lagrange theory with minimum fuel consumption criteria. Instead of using switch ...
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In this research, the problem of optimal trajectory design of an upper stage is considered for satellite injection into Geostationary orbit in 3-Dimensional space. The optimal multi-burn trajectory is obtained based on Euler-Lagrange theory with minimum fuel consumption criteria. Instead of using switch function for obtaining the switching times, which complicates the numerical solution of the optimal control problem, the presented algorithm uses a simple and optimal process to find the burn and coast times. To solve the tow point boundary value problem, an improved indirect shooting method with high performance is used which in addition to having higher precision, converges very fast to the desired condition.
Research Paper
H. Kazemi; Ali Akbar Golro
Volume 9, Issue 4 , April 2017, Pages 27-37
Abstract
International regulations consist of rights and obligations of states in relation to space. States should respect the international obligations with all of their public and private sectors. Based on the 1967 outer space treaty, states should control and monitor natural and legal persons involved in space ...
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International regulations consist of rights and obligations of states in relation to space. States should respect the international obligations with all of their public and private sectors. Based on the 1967 outer space treaty, states should control and monitor natural and legal persons involved in space activity. They usually approve the required laws and regulations in their national law according to the international responsibilities in order to monitor their respective institutions. Monitoring space activities are on the basis of international law within the sovereignty of a country based on the regulatory environment for licensing space activities and establishing appropriate authority. Every state has its own mechanism for issuing the required licenses. However, there are common procedures to monitor space activities, such as launching in the international law, analyses monitoring space activities in national laws and regulations of some countries in comparative laws.
Research Paper
Reza Yavari; Iman Mohammadzaman; Mohammad Reza Arvan
Volume 9, Issue 4 , April 2017, Pages 39-50
Abstract
In this paper, a novel integrated guidance and control (IGC) approach is designed using the combination of backstepping and sliding mode control methods. In contrast to the traditional methods combining the kinematic and dynamic equations and deriving a state space model as an integrated unit model, ...
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In this paper, a novel integrated guidance and control (IGC) approach is designed using the combination of backstepping and sliding mode control methods. In contrast to the traditional methods combining the kinematic and dynamic equations and deriving a state space model as an integrated unit model, the proposed method designs the guidance and control problem in a single loop. This algorithm is robust with respect to the uncertainties in the target acceleration and missile dynamic model. Simulation results using six-degrees-of-freedom simulation aerodynamic model (6DOF) and three-dimension (3-D) engagement show that the proposed IGC design, with guidance and control dynamic synergism, eventuates interception with the maneuvering target.
Research Paper
Javad Salem; hossein pilaram; seyyed mohammad alavi
Volume 9, Issue 4 , April 2017, Pages 51-63
Abstract
For the detection of and tracking thelow earth orbit Satellites (LEO), there are different methods such as optic, laser and radar tracking, among which radar tracking is the best. Since the common linear tracking filters deployed in available radars are not able to estimate the position of the non-linear ...
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For the detection of and tracking thelow earth orbit Satellites (LEO), there are different methods such as optic, laser and radar tracking, among which radar tracking is the best. Since the common linear tracking filters deployed in available radars are not able to estimate the position of the non-linear dynamic satellites, it is advisable to use non-linear filters. In this paper, firstly, the satellite motion path around the earth as well as radar observations are produced by the STK software. Accordingly, the samples are fed to non-linear Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF). Finally, the performance of the aforementioned filters is studied through evaluation of RMS position and estimation errors. Simulation results demonstrate that the Unscented Kalman filter has a better performance in terms of accuracy with respect to the Extended Kalman filter. In addition, using this method, theerror of observations decreases 50% along the range and 70% along the azimuth and elevation.
Research Paper
Vahid Nikbakht; Ali Kazemi; Zahra Hajebrahimi; Neda Khaledi; Mohammad Asadi golzar
Volume 9, Issue 4 , April 2017, Pages 63-68
Abstract
Endothelial cells differently respond to microgravity condition. The evolution of these responses leads to a more clear understanding of cardiovascular diseases in both gravity and micro-gravity conditions. The aim of this study was to investigate the effects of microgravity condition on serum levels ...
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Endothelial cells differently respond to microgravity condition. The evolution of these responses leads to a more clear understanding of cardiovascular diseases in both gravity and micro-gravity conditions. The aim of this study was to investigate the effects of microgravity condition on serum levels of vascular endothelial growth factor as a motivator for angiogenesis and vasculogenesis processes. A total of 20 rats were randomly divided into two groups including control group and suspension group. The results showed that the VEGF levels of suspension group were higher than control group but it was not significant (P> 0.05). It seems that the hindlimb suspension model used for stimulating microgravity condition does not affect the VEGF in serum levels in male Wistar rats. This may be the result of the body's adaptive response after six weeks. Another probable reason is that VEGF does not play an effective role in cardiovascular changes in microgravity condition. Also the influences of other factor may affect the results.