ResearchPaper
communications
Peyman Mohammadi; Mehdi Alemi Rostami
Articles in Press, Accepted Manuscript, Available Online from 19 June 2023
Abstract
One of the most important issues related to the power supply of TWTA lamps in satellites is to have low ripple, high efficiency, high reliability and optimal volume and weight,. In this article, the efficiency and reliability of high voltage DC/DC electronic-power converter is optimized for use in satellite ...
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One of the most important issues related to the power supply of TWTA lamps in satellites is to have low ripple, high efficiency, high reliability and optimal volume and weight,. In this article, the efficiency and reliability of high voltage DC/DC electronic-power converter is optimized for use in satellite and TWTA lamps. The goal of optimization using multi-objective genetic algorithm (NSGA-II) in this article is to minimize the objective function, which includes efficiency and reliability. Markov model is used to evaluate reliability, in which short-circuit and open-circuit errors are considered for circuit switches and diodes, and short-circuit errors are considered for passive circuit elements. for optimization, first, the input variables of the algorithm are determined as the input of the objective function, so that with the help of sensitivity analysis, the parameters that have low sensitivity and their changes do not have a major impact on the objective function are eliminated. parameters of NSGA-II algorithm, including the number of iterations, the number of populations, and the probability have been determined for the accurate calculation of circuit variables. the results section this method, in addition to maintaining high efficiency, with the optimal selection of elements, high reliability can be achieved .
ResearchPaper
space sciences and exploration
Iman Shafieenejad
Articles in Press, Accepted Manuscript, Available Online from 25 July 2023
Abstract
The aim of this research is to optimize the trajectory of a low-trust spacecraft carrying biological cargo. Reducing the radiation stresses of the Van Allen belt is the optimal criterion of the optimal control problem of the orbital transfer from the low orbits to the high orbits. Since the minimum radiation ...
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The aim of this research is to optimize the trajectory of a low-trust spacecraft carrying biological cargo. Reducing the radiation stresses of the Van Allen belt is the optimal criterion of the optimal control problem of the orbital transfer from the low orbits to the high orbits. Since the minimum radiation stress criterion introduced in this article is not among the conventional optimality criteria, solving the above optimal control problem will be complicated and the honey bee optimization method has been used. The optimization of the path in this article is done by rewriting the motion equations based on the control variable and solving the new motion equations with the help of bee optimization. The main advantage of the method used in this problem is the use of optimal control theory and population-based optimization methods with a global approach. In the presented new method, the optimal control problem is simplified by redefining the differential equation system, and the results show the accuracy and ease of solution. Results of the optimal criterion of the minimum time and the minimum radiation stresses presented in this article, the criterion of the minimum radiation causes an increase of 8.89% in the transfer time.
ResearchPaper
GPS and navigation GPS)، GLONASS، GALILEO
Seyed Ali Zahiripour
Articles in Press, Accepted Manuscript, Available Online from 29 August 2023
Abstract
In this article, a method for increasing the accuracy of the initial alignment process of inertial navigation systems with a stable platform is presented through state feedback control in flight mode. In the presented method, the state feedback controller is designed by using the stable plate deviation ...
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In this article, a method for increasing the accuracy of the initial alignment process of inertial navigation systems with a stable platform is presented through state feedback control in flight mode. In the presented method, the state feedback controller is designed by using the stable plate deviation angles and the sensor error which is extracted with the help of Kalman filter. To do this, while checking the observability of the system, by adding suitable flight maneuvers and expressing the equations of propagation of navigation error, in the form of a fixed piece system with time, it is possible to estimate the angles and errors of the sensors in the align phase. The groundwork is provided for the design of state feedback. Then, taking into account the stable platform motion equations and using the principle of separation of observer and controller design, a state feedback controller is designed. In the end, the simulation results of the proposed method show an increase in the accuracy of the alignment process and, consequently, an increase in the accuracy of the navigation, compared to the conventional output feedback method.
ResearchPaper
communications
Jaafar Bazrafshan; Fatemeh Sadeghikia; Ali Karami Horestani; Mohamed Himdi
Articles in Press, Accepted Manuscript, Available Online from 25 September 2023
Abstract
This paper presents a novel approach for designing a reconfigurable and steerable antenna utilizing plasma dielectric slabs along the aperture of a pyramidal horn antenna. The antenna offers electronic control over both the radiation gain and the direction of the main beam. The proposed configuration ...
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This paper presents a novel approach for designing a reconfigurable and steerable antenna utilizing plasma dielectric slabs along the aperture of a pyramidal horn antenna. The antenna offers electronic control over both the radiation gain and the direction of the main beam. The proposed configuration consists of four plasma slabs aligned perpendicular to the horn aperture along the horn axis, complemented by four diagonally connected plasma slabs. Each plasma slab can be independently switched ON or OFF, enabling dynamic adjustment of the radiation gain and steering of the main beam. Numerical investigations demonstrate that toggling the plasma slabs or controlling the plasma frequency of these slabs allows for fine-grained control over the radiation gain and beam steering of the pyramidal horn antenna. The selection of appropriate dimensions and angles for the plasma slabs plays a crucial role in achieving the desired beam steering angle and radiation gain control. To validate the concept, the proposed antenna configuration is designed and numerically simulated at a frequency of 10 GHz. The results indicate that the radiation gain of the antenna can be significantly enhanced, reaching up to 6.5 dBi. Additionally, the main beam direction can be steered within a range of ±12 degrees.
ResearchPaper
Space subsystems design: (navigation, control, structure and…)
hamid reza ali mohamadi; Hassan Naseh
Articles in Press, Accepted Manuscript, Available Online from 25 September 2023
Abstract
Achieving to new technologies with high reliability, along with reducing the cost and time of the design cycle, is one of the most important challenges in complex systems. In this paper, reliability based design of a space system is discussed in the conceptual design phase. Normally, there are eight ...
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Achieving to new technologies with high reliability, along with reducing the cost and time of the design cycle, is one of the most important challenges in complex systems. In this paper, reliability based design of a space system is discussed in the conceptual design phase. Normally, there are eight steps in the design for reliability. The first step, planning, and the next seven steps that applied for the liquid propellant engine with electro-pump technology included: determination of failure modes; reliability modeling; reliability allocation; propagation of uncertainty; Implementation of the chosen method in reliability analysis; reliability prediction and reliability evaluation. Therefore, in this research has been performed to achieved method and implementation steps of reliability design in the conceptual design phase of a space system.
ResearchPaper
Space subsystems design: (navigation, control, structure and…)
Arian Zakiani; Seyed Hassan Sedighy; Razieh Narimani
Articles in Press, Accepted Manuscript, Available Online from 01 October 2023
Abstract
Due to the limited communication time between LEO satellites and the ground station and large volume of satellite image data, it is necessary to establish a high transmission rate connection. Therefore, the use of a high-efficiency satellite antenna is inevitable. In order to use the limited viewing ...
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Due to the limited communication time between LEO satellites and the ground station and large volume of satellite image data, it is necessary to establish a high transmission rate connection. Therefore, the use of a high-efficiency satellite antenna is inevitable. In order to use the limited viewing time of the satellite, it must be possible to communicate with the ground station at low angles and change the main beam direction of satellite antenna to the direction of the ground station. The proposed array is composed of 8 antenna elements with a compact microstrip feed network. Low profile structure, circular polarization, high gain and low cost specifications of this proposed antenna array, candidate it for conformal array antenna in satellite applications.
ResearchPaper
space policy
Hadi Jalili
Articles in Press, Accepted Manuscript, Available Online from 17 October 2023
Abstract
In this paper, the models of space technology development in regional countries have been studied first, and the main criteria of each of these models have been classified. In this research, by ignoring the leading countries such as USA, Russia, European Union, China, Japan and India, the prominent countries ...
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In this paper, the models of space technology development in regional countries have been studied first, and the main criteria of each of these models have been classified. In this research, by ignoring the leading countries such as USA, Russia, European Union, China, Japan and India, the prominent countries of the region in the field of space technology have been investigated. These countries include the occupying regime of Al-Quds, South Korea and Turkey in the first degree of importance and the United Arab Emirates, North Korea, Kazakhstan and Pakistan in the second degree of importance. Then, SWOT analysis has been done for the space technology trends in the country, and by considering the requirements of the space technology development models, the proper development model has been introduced with the relevant requirements. According to the obtained results, the indigenous development model is the best space technology development model for the country, and one of the most important infrastructures needed in this model is to have a suborbital laboratory and a minimal mass orbital launch service.
ResearchPaper
Space subsystems design: (navigation, control, structure and…)
Amir Labibian
Articles in Press, Accepted Manuscript, Available Online from 18 October 2023
Abstract
IIn high resolution remote sensing satellites, meeting stability and pointing requirements are very crucial in mission’s success. In this regard, usually, very accurate gyroscopes are utilized as one of the main attitude sensors. In order to avoid decreasing attitude estimation accuracies, gyroscopes ...
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IIn high resolution remote sensing satellites, meeting stability and pointing requirements are very crucial in mission’s success. In this regard, usually, very accurate gyroscopes are utilized as one of the main attitude sensors. In order to avoid decreasing attitude estimation accuracies, gyroscopes data should be calibrated in appropriate time intervals. In this research an Extended Kalman Filter (EKF) based approach is investigated for gyro calibration. Therefore, at first, a model which contains main gyro parameters, namely, biases, scale factors and misalignments is proposed. Then, an EKF based algorithm for gyro parameters estimation is presented. Next, a Multiplicative Quaternion Extended Kalman Filter (MQEKF) which uses star sensor data as measurement is applied for attitude estimation. Finally, in order to evaluate the performance of the proposed gyro calibration method in attitude control loop, a quaternion feedback controller is implemented. The simulation results show that satellite’s stability and pointing are maintained with accuracies better than 0.005 deg/second and 0.15 deg which demonstrate the proposed method will be beneficial for missions with tight control requirements.
