Research Paper
Space systems design (spacecraft, satellites, space stations and their equipment)
Alireza Toloei; Mohammad Fatehi; Behrooz Keshtegar
Volume 14, Issue 3 , September 2021, Pages 1-14
Abstract
In this paper, a design of a hydrazine monopropellant system is proposed based on the maximum likelihood for the presentation of uncertainties, without any specific assumptions about the type of distribution and even uncertainty in distribution parameters by the johnson distributions family. The maximum ...
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In this paper, a design of a hydrazine monopropellant system is proposed based on the maximum likelihood for the presentation of uncertainties, without any specific assumptions about the type of distribution and even uncertainty in distribution parameters by the johnson distributions family. The maximum likelihood method for the combination of spars point and interval data has been added to a separate formulation for design variables and parameters. This formulation is also suitable for both epistemic and aleatory uncertainty with three presentation types of spars points, single interval, and multi-interval.
Research Paper
Space subsystems design: (navigation, control, structure and…)
M. Navabi; Ahmad Ebrahimi
Volume 14, Issue 3 , September 2021, Pages 15-22
Abstract
Turbulence in the spacecraft tanks has undesirable effects during maneuvers. Therefore, considering the importance of the correct orbit maneuver to reach the target orbit, it is necessary to model and select a proper method to control it before performing the orbital maneuvers. In this paper, by using ...
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Turbulence in the spacecraft tanks has undesirable effects during maneuvers. Therefore, considering the importance of the correct orbit maneuver to reach the target orbit, it is necessary to model and select a proper method to control it before performing the orbital maneuvers. In this paper, by using a new method for modeling turbulence in reservoirs and for the first time, spacecraft attitude control and turbulence control are simulated using this model. Fuel turbulence is modeled using a moving pulsed ball model, and the whole system's dynamic equations are derived using Krishehoff equations. The maneuver of the spacecraft and the motion of the moving pulsed ball is considered in the plane; therefore, the spacecraft and pulsed ball system will have four degrees of freedom. simulation results show successful modeling and simultaneous control of turbulence and situation
Research Paper
Remote sensing
Kobra Yaghoubi; Alireza Safdarinezhad; Marzieh Jafari
Volume 14, Issue 3 , September 2021, Pages 23-37
Abstract
Image fusion is known as a synergetic process for merging multispectral and panchromatic images contents. So far, various methods have been developed in which the usage of the frequency domain is one of them. The frequency-based image fusion techniques are performed using high and low pass filters. So, ...
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Image fusion is known as a synergetic process for merging multispectral and panchromatic images contents. So far, various methods have been developed in which the usage of the frequency domain is one of them. The frequency-based image fusion techniques are performed using high and low pass filters. So, the determination of the sizes of these filters would be a challenge. In this paper, a weighted index is proposed to determine the sizes and shapes of the low and high filters in fusion of the panchromatic and multispectral images. In the proposed method, the weights of the spectral and spatial indicators are independently estimated for each image. So, the effects of the differentiation of the image contents and different range of the indicators are properly adjusted to reach the optimum filtering. The comparison of the best results obtained from the proposed method with the other well-known fusion methods, in the used datasets, was indicated an average improvement of 58% in RMSEs.
Research Paper
Space systems design (spacecraft, satellites, space stations and their equipment)
Hojat Taei; Mahmood Haghighat Esfahani; Sajjad Yadegari Dehkordi
Volume 14, Issue 3 , September 2021, Pages 39-50
Abstract
In this paper, a novel Comprehensive Preference-based Design (CPD) approach is presented which attempts to achieve subjective attributes that are defined in the concept of maximization of designer/customer's satisfaction in addition to objective goals which are formulated in the form of minimization ...
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In this paper, a novel Comprehensive Preference-based Design (CPD) approach is presented which attempts to achieve subjective attributes that are defined in the concept of maximization of designer/customer's satisfaction in addition to objective goals which are formulated in the form of minimization of a performance criterion in a two-phase structure using two nested optimizers.In the first phase of CPD,using the concept of satisfaction,the subjective preferences of the designer/customer are defined in terms of fuzzy relationships and operators.Whereas the results of this phase are inaccurate,in the second phase,it is attempted to define a performance criterion and in order to achieve an optimal operational plan,attitude parameters and the compromises needed to meet the designer/customer's preferences are implemented.The methodology is utilized to design of a space launch vehicle for delivering 1200 kg payload to a 750 km orbit.Comparison of the results shows that despite the higher mass of launch vehicle designed by CPD,overall design satisfaction is higher and designer/customer's preferences have been satisfied.
Research Paper
Space subsystems design: (navigation, control, structure and…)
Milad َAzimi; Samad Moradi
Volume 14, Issue 3 , September 2021, Pages 51-63
Abstract
The free and forced vibration analysis of a rotating large flexible structure with a single crack is investigated using the Homotopy Perturbation Method (HPM). The crack is modeled with a torsional spring element on a structure that follows the Euler-Bernoulli theory. The nonlinear equations of motion ...
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The free and forced vibration analysis of a rotating large flexible structure with a single crack is investigated using the Homotopy Perturbation Method (HPM). The crack is modeled with a torsional spring element on a structure that follows the Euler-Bernoulli theory. The nonlinear equations of motion of the co-rotational system considering centrifugal forces are derived using the calculus of variation and the Assumed Mode Method (AMM). Applying the Galerkin method, the spatial domain is extracted and the time domain is transformed into a second-order nonlinear differential equation. The results of time response, phase plane, and bifurcation diagrams for different functional parameters variations such as base angular velocity, crack position and stiffness have been analyzed. Moreover, it is shown that as the base angular velocity increases, a tensile force appears along the cracked structure axis, stiff it, and shifts the backbone to the right, this can highly affect the nonlinear features of the system.
Research Paper
Space systems design (spacecraft, satellites, space stations and their equipment)
Abbas Saeidi; Nasser Rahbar; Mohammad Ali Alirezapouri
Volume 14, Issue 3 , September 2021, Pages 65-73
Abstract
In recent years, according to progress of aerospace industries particularly satellites it has been paying much attention to attitude determination of satellite. Attitude determination of satellite in various ways, such as: radio, radar, optical methods and using GPS, q and kalman filter is done, that ...
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In recent years, according to progress of aerospace industries particularly satellites it has been paying much attention to attitude determination of satellite. Attitude determination of satellite in various ways, such as: radio, radar, optical methods and using GPS, q and kalman filter is done, that each of these methods has advantages and disadvantages. Due to disturbance in space, high accuracy in attitude determination, various algorithms to obtain properly accurately attitude, desirable access to position, velocity and time of satellite to achieve desired attitude determination satellite are considered a top priority. However in this Paper, first we review the various methods for attitude determination satellite and then examine of operation and relations of algorithms discussed. This Paper focus on the advantages and disadvantages of qEKF algorithm in compare to other methods are available.
Research Paper
GPS and navigation GPS)، GLONASS، GALILEO
Mohsen Shamirzaei; Mehran Mir Shams
Volume 14, Issue 3 , September 2021, Pages 75-90
Abstract
The main task of the study is to estimate the position error in an inertial navigation system by integrating it with the visual system. The case study is a spacecraft that must accurately measure its position relative to a predetermined landing point. The spacecraft is assumed to be augmented GNSS navigation. ...
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The main task of the study is to estimate the position error in an inertial navigation system by integrating it with the visual system. The case study is a spacecraft that must accurately measure its position relative to a predetermined landing point. The spacecraft is assumed to be augmented GNSS navigation. Therefore, when satellite signals are dropped out or when landing on a moving marine platform, the data of the vision navigation system replaces the information of the satellite navigation system and improves the accuracy of the spacecraft navigation system. An Extended Kalman filter has been used to integrate inertial and vision navigation system information. In addition, the output data of the vision system, in order to be used in the Kalman filter measurement equations, is first processed by the recursive least square filter. The relevant relations are given and based on the results of software simulation, the efficiency of the proposed method is shown.
Research Paper
Remote sensing
S. Andishe Moezzi; Mohamad Ali Masnadi-Shirazi
Volume 14, Issue 3 , September 2021, Pages 91-100
Abstract
synthetic aperture radar (SAR) for ground moving target indication (GMTI) and imaging (GMTIm) have been gaining increasing interests for both civilian and military applications. Because SAR is generally designed for imaging a stationary scene, the SAR image of a moving target will be both displaced and ...
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synthetic aperture radar (SAR) for ground moving target indication (GMTI) and imaging (GMTIm) have been gaining increasing interests for both civilian and military applications. Because SAR is generally designed for imaging a stationary scene, the SAR image of a moving target will be both displaced and smeared.More specifically, by exploiting the inherent sparsity of the moving targets in the clutter-suppressed SAR image domain, in this article. the intended SAR-GMTIm problem is solve by a sparse Bayesian perspective.The theory of CS has been successfully applied to SAR/ISAR imagery to achieve high cross-range resolution with a limited number of pulsesIn order to evaluate the quality of images, we apply the target-to-clutter ratio (TCR), which is commonly used in syntheticaperture radar (SAR) image assessment.The proposed algorithm shows a 10-dB higher TCR compared to the conventional algorithm.
Research Paper
Remote sensing
Fereydon Nobakht Orsi; Abdolreza Safari; Amir Khodabandeh
Volume 14, Issue 3 , September 2021, Pages 101-108
Abstract
In this paper, we discussed standard point positioning technique based on the single frequency code-based (C/A) receivers. Then, we presented its performance by means of different measures. However, the use of one single frequency GPS receiver to obtain high-precision positioning make a major challenge ...
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In this paper, we discussed standard point positioning technique based on the single frequency code-based (C/A) receivers. Then, we presented its performance by means of different measures. However, the use of one single frequency GPS receiver to obtain high-precision positioning make a major challenge due to the environmental biases, in particular the ionospheric effects are handled. The main objective of the present study is to integrate a inospheric model such as Klobuchar Inospheric Model (KIM) with imprecise code (C/A) observations under intense geomagnetic storm conditions, then, to obtain dm level positioning accuracy using Kalman filter. For this purpose we used code (C/A) observations on two different days (February 26, 2018 and December 20, 2015) at Tehran station. The results show that we could obtain multi-dm level positioning accuracy under geomagnetic storm condition by using Kalman filter that will be important in the field of kinematic applications.