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.
ehsan maani; Hossein Nejat Pishkenari; Amir Reza Kosari
Volume 11, Issue 3 , December 2018, , Pages 63-71
Abstract
In this paper, the combination of reaction wheels and thrusters is applied to attitude control of a satellite. First, governing equations of satellite attitude dynamics are given using quaternion and PID controller is designed based on the satellite quaternion to determine the applied control torque. ...
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In this paper, the combination of reaction wheels and thrusters is applied to attitude control of a satellite. First, governing equations of satellite attitude dynamics are given using quaternion and PID controller is designed based on the satellite quaternion to determine the applied control torque. By applying the reaction wheels physical constraints such as its maximum torque, its maximum momentum and maximum power on the desired torque, reaction wheels angular momentums and torques are found. The obtained results show that the unsaturated reaction wheels capabilities in attitude control. Results also show that the wheels saturation leads to error in control and increases the Euler angles and quaternions. Satellite thrusters are utilized to reaction wheels de-saturation and attitude control simultaneously.Three different strategies are proposed in this paper for wheels de-saturation using thrusters. Two well known methods, pulse width modulator (PWM) and pulse width pulse frequency (PWPF) modulator are used to attitude control using thrusters. All methods are compared together and the optimal method is proposed for the satellite attitude control. This paper results can be useful in design and control of different class of satellites.
investigating space radiation
Hamideh Daneshvar; Masoud Khoshsima; Abolfazl Dayyani
Volume 12, Issue 3 , September 2019, , Pages 63-71
Abstract
One of the important issues to be considered in the design of space systems is the attention to the difference between the terrestrial and space environment. This issue changes the design and affects all subsystems of space systems. Radiation damage due to space radiation can cause disturbances in the ...
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One of the important issues to be considered in the design of space systems is the attention to the difference between the terrestrial and space environment. This issue changes the design and affects all subsystems of space systems. Radiation damage due to space radiation can cause disturbances in the functioning of space systems. In this paper, with a computational approach examines the most important radiation damage involving TID, DD and SEU in two satellites that have missions in LEO orbit. The calculations were performed using the OMERE software and finally, a comparison was made between different models for achieving different types of radiation damage.
Space Ground Segment: receiving, transmitting, controlling and data processing
Ali Sadeghzade; S. Hasan Sedighi; Mohamad Soleimani
Volume 13, Issue 3 , September 2020, , Pages 63-68
Abstract
In this paper, an anti-jamming GPS array antenna with seven antenna elements on the conformal structure is proposed for GPS applications by switching on/off the antenna ports. In this proposed antenna, when the received power is high, the antenna feeds are switched off to create null in the direction ...
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In this paper, an anti-jamming GPS array antenna with seven antenna elements on the conformal structure is proposed for GPS applications by switching on/off the antenna ports. In this proposed antenna, when the received power is high, the antenna feeds are switched off to create null in the direction of jammer to reduce the jammer effect. This structure composed of seven patch elements where each element placed on special face of the structure. Whatever antennas be more directive, we can create deeper nulls. These specifications introduce this antenna as a good candidate for GPS applications to mitigate the jammer effects.
Space subsystems design: (navigation, control, structure and…)
M. Navabi; M. Salehi
Volume 16, Issue 2 , June 2023, , Pages 63-77
Abstract
In a flying system, attitude control is one of the essential subsystems. In this subsystem, estimating the current state is very important to control the state, which is achieved by considering the attitude sensors. Comprehensive research is being done today to reduce the cost of Attitude sensors in ...
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In a flying system, attitude control is one of the essential subsystems. In this subsystem, estimating the current state is very important to control the state, which is achieved by considering the attitude sensors. Comprehensive research is being done today to reduce the cost of Attitude sensors in applications such as drones, satellite simulation platforms, etc. For this purpose, sensors based on Micro-electromechanical Systems have received much attention due to their small size and low energy consumption. This model of sensors, despite its many advantages, has various noises and disturbances that require the application of fusion and estimation algorithms to obtain an acceptable output. In this research, to determine the attitude of the test platform, data fusion algorithms including complementary filter, Kalman filter, and Extended Kalman filter are implemented on a low-cost sensor. The mentioned estimation methods were implemented on the test platform and by determining the effective parameters in the estimation algorithms, the desired accuracy was obtained. The module obtained in these experiments is comparable to more expensive sensors.
physiology and space medicine (astrobiology)
maryam salavatifar
Volume 17, Issue 1 , March 2024, , Pages 63-71
Abstract
Earth's gravity is one of the forces that constantly affects living organisms. It's changes can affect organisms behavior and performance. Study of such effects can lead to the discovery of new practical methods. Heavy metal toxicity have a lot of risks to human health. They sometimes act as a pseudo ...
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Earth's gravity is one of the forces that constantly affects living organisms. It's changes can affect organisms behavior and performance. Study of such effects can lead to the discovery of new practical methods. Heavy metal toxicity have a lot of risks to human health. They sometimes act as a pseudo element of the body and they may even interfere with metabolic processes. Cadmium as one of the most hazardous heavy metals, cause defects in DNA repair following the induction of oxidative stress, DNA damage and may lead to cancer. Several methods have been introduced to remove heavy metals from drinking water. Bioremoval by probiotic is one of these safe methods. In this study Lactobacillus acidophilus effect on cadmium bioremoval was measured in microgravity and Mars gravity conditions. The results demonstrated that the 24-hour water treatment by L. acidophilus removed 43.77% of the cadmium concentration in the Earth gravity, 54.74% under microgravity and 54.84% in Mars gravity. Statistical analysis showed that L. acidophilus was effective in cadmium bioremoval and this ability was maintained even with gravity changes. Therefore, this bacterium can be used to remove heavy metal pollution during space missions in order to maintain the health of astronauts.
Hossean Bolandi; Mohammad Hassan Ashtari; Ghodratollah Barati; Jafar Kochaki; Mohammad Sadegh Zayghami; Majed Esmaeilzadeh
Volume 8, Issue 3 , October 2015, , Pages 65-70
Abstract
In the mission of satellites, instantaneous positioning and estimation of the future position are necessary. In the communication satellite, this matter is so important. Thus in the Tadbir satellite, for the first time in the country, we consider an orbit determination subsystem that equipped with a ...
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In the mission of satellites, instantaneous positioning and estimation of the future position are necessary. In the communication satellite, this matter is so important. Thus in the Tadbir satellite, for the first time in the country, we consider an orbit determination subsystem that equipped with a spaceborne GPS receiver and contains appropriate algorithms in order to achieve satellite position data during the lunch period and in the orbit. In this paper a brief review of the software and hardware parts of this subsystem is presented. In additional the process of testing to achieve good performance, including functional tests of ODS processor board and functional test of GPS receiver with GPS simulator, environmental condition tests, mechanical tests, thermal vacuum cycle tests, electromagnetic compatibility test and finally integrated satellite tests are stated. This paper, in addition to a description of the Tadbir satellite orbit determination subsystem, an implementation testing of a satellite subsystem is demonstrated, which can be useful to other space field researchers. Â
Mohammad Moumivand; hasan mohammadkhani; javad heydari; mohammad hosein vaezi
Volume 10, Issue 2 , September 2017, , Pages 65-72
Abstract
Determining aerodynamic coefficients and control and stability derivatives play animportant role in the development of flight vehicles. In this paper, roll damping coefficientof BASIC FINNER standard model is determined at different attack angles and withvarious Mach numbers using numerical Sliding Mesh ...
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Determining aerodynamic coefficients and control and stability derivatives play animportant role in the development of flight vehicles. In this paper, roll damping coefficientof BASIC FINNER standard model is determined at different attack angles and withvarious Mach numbers using numerical Sliding Mesh method. Also, the impact of theeffective parameters such as amplitude and frequency of oscillation, time step and numberof iteration in each step in numerical solution are investigated to determine the rolldamping coefficients. Geometry modeling and grid generation and the flow analysis aredone by ANSYS CFX and ANSYS FLUENT software, respectively. In this simulation,Euler’s flow equations, compressible and unsteady flow, finite volume method and densitybased solver with explicit formulation and first-order accuracy for a numerical solutionare used. To evaluate the results of a numerical study, a comparison is made between theexperimental data and MD results, indicating that the results have a good accuracy.
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.
Seyyed Ghasem Zamani; vahid bazzar
Volume 10, Issue 3 , December 2017, , Pages 67-75
Abstract
The contribution of injured person in creating or worsening the damage caused by space objects is important in determining the international liability for those. This contribution, which is accepted only in respect of damage caused by space objects located in places other than outer space -land orair- ...
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The contribution of injured person in creating or worsening the damage caused by space objects is important in determining the international liability for those. This contribution, which is accepted only in respect of damage caused by space objects located in places other than outer space -land orair- will reduce or eliminate the international liability, depending on the extent of the contribution of the injured person. However, in cases where damage is caused by an act contrary to the international laws, this rule will not apply. In order to apply this rule, the contribution of main injured person for the damages to whom theinternational responsibility will be considered, and the contribution of state which acted the diplomatic protection of its subject or the contribution of member states of the injured International Organization are not considered. In addition, examining the rule of the impact of contribution of injured person, this paper tries to examine the issues related to this rule in the international space law.
Space subsystems design: (navigation, control, structure and…)
Mahsa Javaheripour; Ahmad Reza Vali; Vahid Behnam Gol; Firouz Allahverdizadeh
Volume 15, Issue 3 , September 2022, , Pages 67-78
Abstract
Proportional navigation is one of the most widely used methods in guiding flying objects. This method requires the rotation rate of the line between the interceptor and the target to calculate the guidance command. For a variety of reasons, including cost savings, simple sensors are used to measure tracking ...
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Proportional navigation is one of the most widely used methods in guiding flying objects. This method requires the rotation rate of the line between the interceptor and the target to calculate the guidance command. For a variety of reasons, including cost savings, simple sensors are used to measure tracking information, including line of sight angle. Therefore, some non-measurable information such as the angular velocity of the line of sight must be estimated using mathematical equations. Due to the noise and other problems, the use of derivatives is not desirable in this situation. Therefore, in this paper, an extended nonlinear observer is used to estimate the angular velocity of the line. Due to the nonlinear dynamics of the intercepting of flying objects, a nonlinear type of observer has been selected. By performing a computer simulation, the correct operation of the proposed observer is shown.
physiology and space medicine (astrobiology)
maryam salavatifar; Zahra Hajebrahimi
Volume 12, Issue 1 , April 2019, , Pages 69-76
Abstract
Introduction: Gravity is one of the most important forces exposed to the organisms on the earth which affects the cells, molecules and thus the entire of organism. The purpose of this study is to investigate the effect of the simulated microgravity on the changes of RKIP metastasis suppressor gene expression ...
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Introduction: Gravity is one of the most important forces exposed to the organisms on the earth which affects the cells, molecules and thus the entire of organism. The purpose of this study is to investigate the effect of the simulated microgravity on the changes of RKIP metastasis suppressor gene expression on MDA-MB-231 breast cancer cell line.Materials and Methods: In order to impose microgravity state, cancer cells were placed on clinostat for one and three days. Then RNA was extracted from the cells and RKIP gene expression changes were evaluated by qReal time PCR.Results: The findings showed that the microgravity during one day reduced the RKIP expression level, but with continuing up to three days, the expression returned to the control level.Conclusion: By optimizing the duration of microgravity, it can be likely observed the significant effects on the RKIP gene expression changes and so that useful steps can be taken to discover the cancer mechanisms and its treatment.
Morteza Tayefi; Ghasem Kahe; Mijtaba Mehrafrooz
Volume 12, Issue 4 , December 2019, , Pages 69-77
Abstract
Sounding rockets provide a useful platform for the aerospace research activities in which carry out a research payload to the space and recover it in the ground. In the flight path, it does scientific experiments and acquire the result for more analysis in the ground. All of the well-known aerospace ...
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Sounding rockets provide a useful platform for the aerospace research activities in which carry out a research payload to the space and recover it in the ground. In the flight path, it does scientific experiments and acquire the result for more analysis in the ground. All of the well-known aerospace centers around the world use frequently the various forms of sounding rocket to test and evaluate their sensitive space components. Actually, space qualification process of a space module is completed sometimes through a real space flight using the sounding rocket. In this paper the performance of a MEMS based inertial measurement unit (IMU) is investigated. The investigation result shows that using appropriate filtering, MEMS based IMU can measure appropriately the dynamic behavior of the sounding rocket. These data may be used for further identification and validation tests.
Space systems design (spacecraft, satellites, space stations and their equipment)
Mohsen Sargolzaie; Hamid Fazeli; Mohammadreza Soltani
Volume 15, Issue 2 , June 2022, , Pages 71-80
Abstract
Due to the lack of existence of control surfaces in entry capsules, the subject of static and dynamic stability is always important. In this paper, these coefficients are investigated experimentally for the case of forced oscillation at supersonic flow. In this experimental study, the effects of freestream ...
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Due to the lack of existence of control surfaces in entry capsules, the subject of static and dynamic stability is always important. In this paper, these coefficients are investigated experimentally for the case of forced oscillation at supersonic flow. In this experimental study, the effects of freestream Mach number, mean attack angle and pitch frequency on dynamic stability coefficients were evaluated. According to the results, in Mach 1.8, the geometry starts to be dynamically unstable. One approach to overcome this problem is to change the average attack of angle of the model. This change in the mean attack of angle, similar to the results presented for the five-degree mean angle, will lead to dynamic stability.
communications
Javad Ranjbar; Mohammad Fathi
Volume 15, Issue 4 , December 2022, , Pages 71-88
Abstract
In this paper, in order to provide telecommunication coverage for a wide geographical area, the use of a network consisting of an LEO satellite and a Tethered-Balloon equipped with antenna pointing mechanism is proposed. The proposed telecommunication network is able to send the collected data to a mission ...
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In this paper, in order to provide telecommunication coverage for a wide geographical area, the use of a network consisting of an LEO satellite and a Tethered-Balloon equipped with antenna pointing mechanism is proposed. The proposed telecommunication network is able to send the collected data to a mission center outside the covered region and receive the required telecommands, while providing a telecommunication link between the users in the covered region. To control and point the antenna beams towards desired targets, an Adaptive Dynamic Surface Controller is designed. Determining the required operating modes, designing a mode management algorithm and extracting the appropriate reference trajectories for each operating mode are among the discussed issues in this paper. The Uniform Ultimate Boundary (UUB) stability of the closed-loop system is proved and the performance of the control system is studied by simulation. The proposed communication network and control system are able to provide wide telecommunication coverage in remote areas or emergency situations.
Space New Technologies
Hamed Babaei; Seyyed Amir Gohari; Peiman Mohamadi
Volume 16, Issue 4 , December 2023, , Pages 71-82
Abstract
In this article, a new type of EBG structure known as frequency selective surface (FSS) with reconfigurable capability is investigated. The proposed design introduces a new adjustable band stop filter equipped with PIN diodes. Operating frequency of the FSS structure is in the C-band and in the frequency ...
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In this article, a new type of EBG structure known as frequency selective surface (FSS) with reconfigurable capability is investigated. The proposed design introduces a new adjustable band stop filter equipped with PIN diodes. Operating frequency of the FSS structure is in the C-band and in the frequency range of 4GHz to 8GHz, which at the central frequency of 4.75GHz, provides a bandwidth of about 1 GHz, when the state of the diode being on. The center frequency of this filter is shifted to 5.23 GHz when the diode is off. In fact, this structure is supposed to be used as a type of electromagnetic coating filter for space payload in the next generation satellites. After the design and simulation of the final cell, an equivalent circuit model is also presented to confirm the design and simulation. These structures protect electronic modules of satellite payload against electromagnetic radiation, electronic warfare. The RCS reduction is the other application of the FSS structure.
Hasan Naseh; Mehran Mirshams; Javad Naderifar
Volume 9, Issue 3 , December 2016, , Pages 73-79
Abstract
The main goal of this paper is development of multi-stage Launch Vehicle (LV) system design software based on advanced classical method. This software has been named Launch Vehicle Conceptual Classical Design (LVCCD). This software covers the complete syllabuses of LV System Design (LVSD) course. The ...
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The main goal of this paper is development of multi-stage Launch Vehicle (LV) system design software based on advanced classical method. This software has been named Launch Vehicle Conceptual Classical Design (LVCCD). This software covers the complete syllabuses of LV System Design (LVSD) course. The main characteristic of the software development is to step by step training the LVSD. Also it can help the better understand in the course in the best quality and lower time. The algorithm used in the software developed according to the outline of LVSD (major design parameters, LV's mass-energy equations and velocity losses and etc.) and using the multi-stage LV statistical data. Hence, these advantages led to better understanding and conceive. Also LVCCD can improve the qualification of training. Finally, the LVCCD software evaluated and verified with the design software as Launch Vehicle Conceptual Design (LVCD) and PBRM by using existing multi-stage LV.
Space subsystems design: (navigation, control, structure and…)
Nourbakhsh Fouladi; Neda sadat Seddighi renani
Volume 15, Issue 1 , March 2022, , Pages 73-87
Abstract
In this article, a universal algorithm and engineering software is presented for the conceptual design of cryogenic rocket propulsion system. The algorithm consisting five engine working cycles: pressure fed, gas generator, staged combustion, closed and opened expansion cycles. For validation, the Vulcain ...
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In this article, a universal algorithm and engineering software is presented for the conceptual design of cryogenic rocket propulsion system. The algorithm consisting five engine working cycles: pressure fed, gas generator, staged combustion, closed and opened expansion cycles. For validation, the Vulcain and HM7Bengines were redesigned, the obtained results certifies that the main design parameters have less than 5% errors and the other less than 20%. One of the advantages of this software is the presence of abut150 parameters in the output and 14 diagrams related to the flow behavior in the thrust chamber and cooling vest, which allows the parametric study of the effect of input changes on the outputs.The modeling of mathematical functions and the combustion has been done, by using the MATLAB and CEAsoftware. Finally, by merging in Visual studio programming environment and with the help of C# programming language, a software with GUI is presented.
cellular-molecular biology
Zahra Hajebrahimi
Articles in Press, Accepted Manuscript, Available Online from 30 December 2023
Abstract
Simulated microgravity can change tumor cell adhesion, proliferation, invasion, and metastasis. E-cadherin molecule is a cell-to-cell adhesion regulatory molecule whose expression is reduced in most types of cancer cells. In the present study, the expression of the E-cadherin gene in the MCF-7 breast ...
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Simulated microgravity can change tumor cell adhesion, proliferation, invasion, and metastasis. E-cadherin molecule is a cell-to-cell adhesion regulatory molecule whose expression is reduced in most types of cancer cells. In the present study, the expression of the E-cadherin gene in the MCF-7 breast cancer cell line was studied under simulated microgravity conditions using Clinostat for one and three days using real-time PCR technique and GAPDH as reference gene . Also, the effect of microgravity on cells was evaluated by the MTT test. MTT data showed that microgravity for one and three days has no significant effects on cell proliferation and metabolic activity. Also, microgravity for one day led to a doubling of E-cadherin gene expression. The continuation of microgravity for three days led to a further increase. As a result, microgravity can lead to the reduction of the cancerous phenotype in breast cancer. Therefore, studying cancer cells in a microgravity environment can help us understand the mechanisms that lead to cancer and its progression. Also, these studies can lead to the development of new treatment methods for cancer treatment.
M. Sayanjali; J. Roshanian; A. Ghafari
Volume 1, Issue 2 , December 2008, , Pages 51-56
Abstract
In this paper, based on the Lagrange method, attitude motion equations for a flexible spacecraft have been derived. Flexible appendages are modeled by Euler-Bernoulli beam. Hybrid control scheme ofand sliding mode are used for attitude regulation. Switching between these to algorithm is determined using ...
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In this paper, based on the Lagrange method, attitude motion equations for a flexible spacecraft have been derived. Flexible appendages are modeled by Euler-Bernoulli beam. Hybrid control scheme ofand sliding mode are used for attitude regulation. Switching between these to algorithm is determined using absolute error parameter, so that when this parameter is large (i.e. the attitude is far from its desired conditions) the sliding mode control is used. in contrast, when the spacecraft is close to the desired attitude, the control is based onmethod. This hybrid scheme leads to a fast response and also robustness against uncertainty. Switching surface has been designed so that a certain cost function is minimized. Incontroller design, the first three vibration modes of the flexible spacecraft are considered as well as the Euler angles and their rates.
M. Nasirian; R. Saleh; R. Shojaee
Volume 2, Issue 3 , December 2009, , Pages 51-56
Abstract
What is done in this paper is simulation of telemetry and telecommand communication between satellite and earth station as what exists in real earth station. Three software: Satellite predictive motion software, Monitoring and Control (M&C) software, processing Software are used in the simulation. ...
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What is done in this paper is simulation of telemetry and telecommand communication between satellite and earth station as what exists in real earth station. Three software: Satellite predictive motion software, Monitoring and Control (M&C) software, processing Software are used in the simulation. Satellite predictive motion software uses orbital equation extracted from Two Line Elements (TLE) to generate tracking elevation and azimuth angles of satellite. These angles as text file are input of M & C software. The M & C software has four modes as simulation mode, online mode, test mode and emergency mode. In simulation mode Acquisition Of satellite (AOS), Loss Of Satellite (LOS) and Pass Time (PT) are seen. The angles are produced and transferred to antenna servo system for moving antenna to desirable direction. Time of simulation is controllable and received signal level is displayed simultaneously. In this mode when satellite is observable, the telecommand can be send. In online mode all explained capabilities are valid except changing of time. In test mode antenna axis could move in desirable velocity and acceleration. In the other hand, when the satellite becomes lost, the system enters to emergency mode for searching of satellite. In the normal mode after receiving the telemetry data by M & C software this data as text file transferred to processing software. Processing software by protocol which accepted by satellite (HDLC based) recognizes the first and the end of telemetry frame and then extracts and displays the parameters. The telemetry parameters include online and offline data.
A. R. Alemi Naeeni; J. Roshanian
Volume 6, Issue 4 , January 2014, , Pages 53-62
Abstract
In this paper, a multi-objective guidance scenario has been developed which could be used to improve the accuracy of sub-orbital modules at the entry to the earth’s atmosphere. Developed algorithm could be used for the trajectory shaping and adjusting of the trajectory relative to the desired position. ...
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In this paper, a multi-objective guidance scenario has been developed which could be used to improve the accuracy of sub-orbital modules at the entry to the earth’s atmosphere. Developed algorithm could be used for the trajectory shaping and adjusting of the trajectory relative to the desired position. To achieve defined objectives, it has been organized in three phases relative to different layers of trajectory. In the first phase, using of sensitivity functions which are of less computational burden, improving the accuracy according to the reference trajectory is done. In the second phase, trajectory shaping which is required to achieve desired flight performance is applied which could be designed and performed online in the mission. Finally in the last phase which is relative to low altitudes, improving of the accuracy according to homing rules is performed. Validation of developed algorithm using of a sample guidance problem is presented finally.
Fatemeh Sadeghikia; Ali Karami Horestani
Volume 11, Issue 2 , September 2018, , Pages 55-59
Abstract
The aim of this study is to examine the effects of diameter of ground conductor in an axial mode helical antenna on some of the characteristics of the antenna. It is shown that a proper ratio of diameter of ground plane to diameter of helix can be chosen to make a trade-off between the performance of ...
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The aim of this study is to examine the effects of diameter of ground conductor in an axial mode helical antenna on some of the characteristics of the antenna. It is shown that a proper ratio of diameter of ground plane to diameter of helix can be chosen to make a trade-off between the performance of helical antenna and its mass budget. It is shown through computational analysis that this optimum ratio is about 1.5. The results show that an increase in this ratio increases the mass budget, but it does not improve the antenna performance significantly. The simulation results also indicatethat this ratio is independent of the number of helix turns. After measurement, it was found that the simulation results of the antenna well agreed with its measured results acquired at the anechoic chamber.
M. Jafari; M. Taefi; J. Roshanian
Volume 6, Issue 2 , July 2013, , Pages 57-66
Abstract
Flight dynamic equations have an effective role in aerospace technologies. It can be as cheap and efficient means for correcting errors in the spatial position and velocity in inertial navigation systems. The Inertial navigation system is an ideal solution for motion detection with high accuracy with ...
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Flight dynamic equations have an effective role in aerospace technologies. It can be as cheap and efficient means for correcting errors in the spatial position and velocity in inertial navigation systems. The Inertial navigation system is an ideal solution for motion detection with high accuracy with fast dynamics, but the precise location and status of the system output can be significantly reduced over time. In this paper, inertial navigation system integrated with a navigation aided system based on online solving of flight dynamic equations. For this purpose, the proposed use of the Lagrangian of Kepler equations and three degrees of freedom of Newton's equations of transfer flights dynamic has been studied. Using this method, online high accuracy to be achieved by flight computer. Kalman filter algorithm is used for integrating inertial navigation and flight dynamic equations . Finally, The simulation results including position and velocity errors with regard to fly a prototype space module, for the proposed two conditions were compared and the advantages and disadvantages of each method are presented
A. Chekini; H. R. Naji
Volume 7, Issue 1 , April 2014, , Pages 57-66
Abstract
This paper presents the design procedure and implementation results of a proposed hardware which performs different satellite Image compressions using FPGA Xilinx board. First, the method is described and then VHDL code is written and synthesized by ISE software of Xilinx Company. The results show that ...
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This paper presents the design procedure and implementation results of a proposed hardware which performs different satellite Image compressions using FPGA Xilinx board. First, the method is described and then VHDL code is written and synthesized by ISE software of Xilinx Company. The results show that it is easy and useful to design, develop and implement the hardware image compressor using new techniques of programmable logic tools for space applications. In this paper the proposed hardware uses the proposed hardware, and it is put on board of satellite. Appropriate bit streams are produced by synthesis tools; therefore, we have two bit streams which can be configured at any moment of time according to the user request. When users intend the hardware is reconfigured and changed from JPEG to JPEG2000 or vice versa. The Proposed architecture has some advantages other than previous architectures such as high-speed and real-time processing, high flexibility, low cost, high security and low power consumption. This idea can be utilized in modern commercial hardware space board for data compressing due to using partial reconfiguration technique.
