Farhd Fani Saberi
Volume 8, Issue 3 , October 2015, , Pages 15-26
Abstract
In this paper, achieving of Stereo-Imaging scenario by a remote sensing satellite will be presented. Then a suitable attitude control system will be designed using 4 reaction wheels with pyramidal structure to fulfill large angle maneuvers of stereo-imaging scenario. The proposed attitude control system ...
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In this paper, achieving of Stereo-Imaging scenario by a remote sensing satellite will be presented. Then a suitable attitude control system will be designed using 4 reaction wheels with pyramidal structure to fulfill large angle maneuvers of stereo-imaging scenario. The proposed attitude control system provide the satellite with the capability of nadir pointing and large angle maneuvers to take different images of a predefined zone from different point of view. In order to verify the performance of the designed attitude control system, a low-cost real time hardware in the loop test bed will be constructed. The constructed test bed is capable of assessing attitude control algorithms in a real time conditions. In the proposed test bed, accurate and real time modeling of satellite dynamics, space conditions, reaction wheels and gyroscopes will be done by the Simulator computer. Finally, performance of the designed attitude controller to achieve stereo-imaging scenario is investigated by implementing the algorithm in the hardware in the loop test bed in a real time condition.
Mostafa Esmaeili
Volume 10, Issue 1 , June 2017, , Pages 15-25
Abstract
Trapped vortex combustor (TVC) is a compact combustor which represents the high efficiency in flame stabilization. In this study, turbulent reacting flow through trapped vortex combustor is numerically simulated. In order to model turbulence, the K-ω-SST and scale adaptive simulation (SAS) models, ...
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Trapped vortex combustor (TVC) is a compact combustor which represents the high efficiency in flame stabilization. In this study, turbulent reacting flow through trapped vortex combustor is numerically simulated. In order to model turbulence, the K-ω-SST and scale adaptive simulation (SAS) models, and to model combustion, the species transport and probability density function (PDF) approaches are used. To verify the numerical model, numerical results are compared with the available experimental data. There is a good agreement between the mean and RMS values of temperature and emission indices (CO, unbernt hydrocarbon (UHC) and NOx) obtained from numerical results and experimental data. Moreover, simulation is performed for different values of equivalence ratios and mainstream inlet temperatures and results show that with a constant value of equivalence ratio, by increasing the mainstream inlet temperature, combustion efficiency increases, while CO and UHC emission indices decrease.
Reza Esmaelzadeh; Abolghasem Naghash; mahdi mortazavi
Volume 10, Issue 3 , December 2017, , Pages 15-24
Abstract
An optimal explicit guidance law that maximizes terminal velocity is developed for the reentry of a vehicle to a fixed target. The equations of motion are reduced with differential flatness approach and acceleration commands are related to the parameters of trajectory. An optimal trajectory is determined ...
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An optimal explicit guidance law that maximizes terminal velocity is developed for the reentry of a vehicle to a fixed target. The equations of motion are reduced with differential flatness approach and acceleration commands are related to the parameters of trajectory. An optimal trajectory is determined by solving a real-coded genetic algorithm. For online trajectory generation, optimal trajectory is approximated. The approximated trajectory is compared with the pure proportional navigation and genetic algorithm solutions. The near optimal terminal velocity solution compares very well with these solutions. The approach robustness is examined by Monte Carlo simulation. Other advantages such as trajectory representation with minimum parameters, applicability to any reentry vehicle configuration and any control scheme, and Time-to-Go independency make this guidance approach more favorable.
Space systems design (spacecraft, satellites, space stations and their equipment)
Alireza Mohammadi; Fathollah Ommi
Volume 13, Issue 4 , December 2020, , Pages 15-23
Abstract
This paper presents numerical study on spray characteristics and droplet distribution by using Lagrangian method in the discrete phase model of CFD. A two-fluid Eulerian method and Lagrangian approach is selected for modeling two phases turbulence flow in mixing chamber and atomization at outlet of nozzle ...
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This paper presents numerical study on spray characteristics and droplet distribution by using Lagrangian method in the discrete phase model of CFD. A two-fluid Eulerian method and Lagrangian approach is selected for modeling two phases turbulence flow in mixing chamber and atomization at outlet of nozzle while turbulence has been modeled by K-ɛ. In this study, water has been used instead of fuel and Nitrogen instead of atomization gas or oxidizer, while their ratio has been considered 0.32 to provide 26 degrees cone angle and this way, droplet‘s characteristic has been studied and compared with maximum entropy methods. Then droplet‘s diameter has been investigated by changing liquid and gas phase flow rateand based on that, we can optimize atomizer ‘s working condition with maximum efficiency with respect to its cone angle, droplet ‘s diameter and velocity and level of penetration by minimum need of experimental tests.
physiology and space medicine (astrobiology)
Farnoush Soltani; Halimeh Hassanpour; Malek Hekmati
Volume 14, Issue 1 , March 2021, , Pages 15-22
Abstract
LED light spectrums are the proper light source for plant research in the International Space Station and the life support system. In the present study, effects of different light spectrums on some growth parameters, and antioxidant activity were investigated in Anthemis gilanica. Seedlings irrigated ...
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LED light spectrums are the proper light source for plant research in the International Space Station and the life support system. In the present study, effects of different light spectrums on some growth parameters, and antioxidant activity were investigated in Anthemis gilanica. Seedlings irrigated with 1/2 Hougland solution under different light spectrums including white, red-blue and deep red. Seedlings were harvested for physiological and biochemical analyzes after 4 weeks. Results showed the fresh and dry weight, relative water content and root length increased under the red-blue light spectrum comparing to other spectrums. Hydrogen peroxide level didn't significantly change under different light spectrums. Seedlings treated with white spectrum showed the highest DPPH scavenging activity. Also, seedlings treated with deep red spectrum showed the maximum shoot length. It seems that decrease of growth under white spectrum is related to transfer carbon and energy sources for antioxidant compound biosynthesis.
Remote sensing
Masoud Dehvari; Saeed Farzaneh; Mohammad Ali Sharifi
Volume 15, English Special Issue , May 2022, , Pages 15-24
Abstract
In this research, three-dimensional and four-dimensional tomography is used to demonstrate the distribution of wet refractivity index of the troposphere. In this model, spherical cap harmonics are used for the horizontal distribution of the wet refractivity index, and empirical orthogonal functions are ...
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In this research, three-dimensional and four-dimensional tomography is used to demonstrate the distribution of wet refractivity index of the troposphere. In this model, spherical cap harmonics are used for the horizontal distribution of the wet refractivity index, and empirical orthogonal functions are used for the vertical distribution of the index. The region of study is in the west California State, and the wet refractivity index is retrieved from the wet tropospheric delay measurements. to validate the results, radiosonde profiles were compared to the tomographically retrieved profiles. The result shows that wet refractivity indices can be retrieved using functional models with RMSE about 2.4 ppm till 3.9 in four-dimension method. The comparisons show that the four-dimensional retrieved profiles shows improvement up to 34 and 42 percentage in mid-day tomography epochs compare to three-dimensional tomography results. Also it can be seen that in mid-night epochs three-dimensional tomography has higher accuracy compare to four-dimension method because of low variation of wet refractivity indices
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
Space subsystems design: (navigation, control, structure and…)
M. Navabi; F. Malekpour
Volume 15, Issue 2 , June 2022, , Pages 15-25
Abstract
In the variable parameter linear method, which is used to express systems with time-varying state-space matrices, the stability and performance of the feedback system are guaranteed, and there is a significant potential for improving efficiency. The dynamics of these systems depend on a variable parameter ...
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In the variable parameter linear method, which is used to express systems with time-varying state-space matrices, the stability and performance of the feedback system are guaranteed, and there is a significant potential for improving efficiency. The dynamics of these systems depend on a variable parameter with time, considered in this research as the angular velocity of the reaction wheel. The values of this parameter are during an unknown period but can be measured by system performance. Using the tabulation gain technique, the stability of the variable parameter system is checked, and the tabulation parameter is selected for estimating practical control factors. The convex algorithm can solve the extracted sufficient conditions converted into linear matrix inequality conditions. By solving these controlling conditions, the tabulated gain is obtained to guarantee the stability and performance of the variable parameter system. Numerical simulation results show the success of the proposed method.
investigating space radiation
Pedram Hajipour; Leila mohammadi; Azam Eidi; Sara Shoorian; Nahid Eidi Esfiani; Seyed Amir Hossein Feghhi
Volume 16, Issue 4 , December 2023, , Pages 15-27
Abstract
One of the damaging factors for the proper functioning of telecommunication payloads are high energy ionizing particles in space, which the use of proper shield is a way to deal with it. In the design of protection, several factors, such as the type of part and the amount of weight acceptable for the ...
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One of the damaging factors for the proper functioning of telecommunication payloads are high energy ionizing particles in space, which the use of proper shield is a way to deal with it. In the design of protection, several factors, such as the type of part and the amount of weight acceptable for the payload.etc.must be taken into consideration. In recent years, in order to reduce the costs of construction and launch, the use of non-space components has been favored.Therefore, the use of shields with the suitable material in with radiation resistance, with respect to the weight budget considerations, will be one of the important challenges .In this paper, the aim is to investigate the methods of reducing the weight budget considering with respect to the radiation damage of ionizing dose. In this regard, a five-year technology development mission in the GEO orbit has been predicted, and the results of simulations and testing of aluminum and polyethylene shielding to check ionizing dose damage, according to the initial and reference weight budget, have been presented and compared. The analysis and evaluation of the test results using polyethylene protection shows a 17.21 percentage reduction between the two external and internal radiation meters.
Saeed Zohoori; saeed shakhesi
Volume 12, Issue 3 , September 2019, , Pages 15-30
Abstract
Using surface guided wave is one of the most reliable methods of structural health monitoring. Mostly the bulk wave is preferred for identification of internal defects, which is inefficient in localizing the surface cracks. In this paper the procedure of ultrasonic surface wave tomography for crack detection ...
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Using surface guided wave is one of the most reliable methods of structural health monitoring. Mostly the bulk wave is preferred for identification of internal defects, which is inefficient in localizing the surface cracks. In this paper the procedure of ultrasonic surface wave tomography for crack detection in an aluminum plate is investigated and applied for three cracks with the length of 4, 7 and 10 milimeters. Analytical equations and numerical simulations are used to extract dispersion curves as a means for selection of plate thickness and piezoelectric characteristics. Layout selection for transducers and providing numerical and experimental models are the next steps of inspection procedure. All the piezoelectric discs are actuated respectively. Meanwhile, other piezoelectric elements are used as sensors and their received signal is stored in both healthy and defected structures for both numerical and experimental models. Definition of signal difference criteria, signal reconstruction and tomogram generation are the last steps of the procedure presented in this paper.
H. Bolandi; F. Fani-Saberi
Volume 2, Issue 2 , July 2009, , Pages 17-26
Abstract
In this paper, a novel and highly accurate attitude estimation method for a LEO satellite is designed. The method is based on multiple model adaptive estimation (MMAE) structure. In this method, the satellite dynamic equation is linearized in a few points in order to increase the computational rate compared ...
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In this paper, a novel and highly accurate attitude estimation method for a LEO satellite is designed. The method is based on multiple model adaptive estimation (MMAE) structure. In this method, the satellite dynamic equation is linearized in a few points in order to increase the computational rate compared with extended Kalman filter (EKF) method. The attitude determination and control system of the satellite is consists of a star sensor, gyroscope and reaction wheels. As known, star sensor is a very power consuming sensor in attitude determination of the satellite; therefore, a lesser power consuming method, using the dynamic model of the satellite along with angular momentum of the reaction wheels, is proposed to estimate the satellite attitude. This method assures the proper operation and the attitude estimation of the satellite in eclipse mode as well. By applying this method, the star sensor is used for a short period of time which reduces power consumption considerably. The performance and effectiveness of the proposed algorithm are investigated through numerical simulations and is compared with extended Kalman filter.
Space systems design (spacecraft, satellites, space stations and their equipment)
Peyman Aliparast
Volume 13, Issue 3 , September 2020, , Pages 17-24
Abstract
in this paper, design, implementation and test of 24 bit acoustic DAQ subsystem for bio-capsule of Pajohesh explorer is presented. the proposed structure has been used B&K 4942 microphone as input sensing element. the proposed DAQ, has 48Ksps speed, 24 bit resolution, 113dB dynamic range and 23 KHz ...
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in this paper, design, implementation and test of 24 bit acoustic DAQ subsystem for bio-capsule of Pajohesh explorer is presented. the proposed structure has been used B&K 4942 microphone as input sensing element. the proposed DAQ, has 48Ksps speed, 24 bit resolution, 113dB dynamic range and 23 KHz BW. we used a ARM Cortex M3 for signal handling and processing. the acquiescing data have been sending to Bio- capsule FC and also recorded in a Micro-SD card. power consumption of the proposed DAQ is obtained 2.8W. the proposed DAQ take a place with dimentions of 40*40*100 mm3 inside of bio-capsule stand.
Space systems design (spacecraft, satellites, space stations and their equipment)
Alireza Rajabi; Noordin Qadiri Massoom; Mohammadali Amirifar; Seyyed Rashad Rouholamini; Pouria Mikaniki; Mohammad Ghorbi; Majid Kamranifar
Volume 15, Issue 4 , December 2022, , Pages 19-29
Abstract
The effects of injector pressure drop on the performance of a catalytic reactor are studied experimentally. The injectors were simple orifices. Dynamic interactions between the injector and the reactor determine the transient behavior of the system. Results showed that the injector pressure drop affected ...
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The effects of injector pressure drop on the performance of a catalytic reactor are studied experimentally. The injectors were simple orifices. Dynamic interactions between the injector and the reactor determine the transient behavior of the system. Results showed that the injector pressure drop affected neither the decomposition reaction efficiency nor the ignition delay time. However, pressure response time increased, and pressure roughness decreased with increasing injector pressure drop. Interestingly, the response time curve had a slope change at a 20% pressure drop. As discussed in the paper, the slope change is a result of cavitation phenomena in high pressure drop. It is concluded that cold injector tests are not enough for injector design validation, and performance tests are necessary tasks.
investigating space radiation
Sarah Shoorian; S. Amir Hossein Feghhi; Hamid Jafari; Reza Amjadifard
Volume 16, Issue 2 , June 2023, , Pages 19-26
Abstract
Protection of astronauts and electronic components in satellites and spacecraft against space rays is one of the most important primary requirements in space missions. In this work, the effect of three materials, aluminum, as the most common material, polyethylene and a graded-z structure, in the protection ...
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Protection of astronauts and electronic components in satellites and spacecraft against space rays is one of the most important primary requirements in space missions. In this work, the effect of three materials, aluminum, as the most common material, polyethylene and a graded-z structure, in the protection of space radiations has been evaluated. The calculations of the dose caused by these radiations on the human body and a silicon piece have been carried out by MCNPX Monte Carlo code,. The dose caused by cosmic rays has been calculated after applying shields of aluminum, graded-z structure and polyethylene. The results showed that by using polyethylene and about 4.4% increase in weight compared to the aluminum shield, it is possible to reduce the dose caused by photons by more than 50% in the human body and 30% in silicon parts, and the dose caused by protons by about 30%. It cut both for astronauts and electronic components. Graded-z shielding performed very well in the dose attenuation caused by photons, but appeared ineffective in the dose attenuation caused by protons.
Javad Shams; Jafar Roshanian
Volume 12, Issue 4 , December 2019, , Pages 19-33
Abstract
In this paper, the hybrid control of the formation flying of spacecrafts has been investigated. The trajectory deflection of space asteroids, which are potentially life-threatening on Earth, are being actively pursued in recent scientific researches. To accomplish this mission, several methods have been ...
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In this paper, the hybrid control of the formation flying of spacecrafts has been investigated. The trajectory deflection of space asteroids, which are potentially life-threatening on Earth, are being actively pursued in recent scientific researches. To accomplish this mission, several methods have been proposed to date, in which case the use of gravity tractor is an indicator and hence the method is used in this paper. The formation flight of spacecrafts technology is a function of the relative dynamic equations, which are also used for its active control. In this way, the PID controller, which is widely used in various industries and inherently has robust properties, has been used as a base controller, and the fuzzy control has been used to improve its adjustment, which results in the results obtained. From simulation, the performance of the combined controller performance is effective.
Space subsystems design: (navigation, control, structure and…)
Amir Reza Kosari; Alireza Ahmadi; Alireza Sharifi; Masoud Khoshsima
Volume 15, Issue 1 , March 2022, , Pages 21-39
Abstract
Very High Resolution Passive Scan Agile Earth Observation Satellites are able to maneuver around all their three body axes and scan the target area in different directions, simultaneously. The most stringent mid-level requirements which dominate their attitude determination and control subsystem performance ...
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Very High Resolution Passive Scan Agile Earth Observation Satellites are able to maneuver around all their three body axes and scan the target area in different directions, simultaneously. The most stringent mid-level requirements which dominate their attitude determination and control subsystem performance are applied in detumbling and fine pointing modes. These performance requirements are maneuverability, agility, accuracy and stability. In this research, first, we derive the analytical and statistical relationships between quantitative criteria of mid-level requirements and spatial resolution as a high-level mission requirement, next the design drivers of reaction wheels are extracted consequently. Then the size, mass and consuming power of an operational satellite and the reaction wheels torque authority and momentum capacity is guesstimated based on its imaging payload size and specifications.
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.
M. Mirshams; H. Karimi; H. Naseh
Volume 1, Issue 2 , December 2008, , Pages 17-25
Abstract
The principle goal of this paper is to introduce Launch Vehicle Conceptual Design (LVCD) software based on multi-parameter optimization idea. The main objectives of this software arereduction of the cost and time of conceptual design phase. This software is user friendly such that an operator familiar ...
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The principle goal of this paper is to introduce Launch Vehicle Conceptual Design (LVCD) software based on multi-parameter optimization idea. The main objectives of this software arereduction of the cost and time of conceptual design phase. This software is user friendly such that an operator familiar with fundamentals of design and launch vehicle mass – energy equations and with primary training operator is capable to work with LVCD.The algorithm used in LVCD, is based on combinational optimization of major design parameters. To this end, ten sub-algorithms will be presented in this design approach. Mass distribution of different stages to launch maximum payload mass to the orbit, pitch program trajectory to get to the maximum final velocity, and providing minimum velocity loss due to gravity, and also minimum axial acceleration of various stages of launch vehicle will be optimized as the results of the presented approach. The optimization process is performed subject to the restrictions. Also, the performance index is optimized in a mutual iteration mechanism (multi-parameter optimization). Evaluation and verification of the presented method is performed using available data of two and three-stage launch vehicles.
H. Bazrafshan; Sh. Baradaran Shokouhi; B. Ghorbani Vagheii
Volume 2, Issue 3 , December 2009, , Pages 19-26
Abstract
Satellite camera Charged Coupled Device (CCD) read out system needs a high Signal to Noise Ratio (SNR). This is because of the special and inevitable space imaging payload noises. These noises include CCD noises, satellite noises such as lack of complete stability, and environmental noises such as atmospheric ...
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Satellite camera Charged Coupled Device (CCD) read out system needs a high Signal to Noise Ratio (SNR). This is because of the special and inevitable space imaging payload noises. These noises include CCD noises, satellite noises such as lack of complete stability, and environmental noises such as atmospheric interferences, charged particles, relative earth and satellite movement and electromagnetic interferences. CCD noises because of their low output voltage compose the main part of the final read out system noise. Therefore if the CCD read out system is not designed properly, SNR declines significantly. These noises depend on CCD characteristics and design parameters such as temperature and frequency. On the other hand, in a satellite temperature and frequency range is partially controllable. The algorithm presented in this paper, with respect to the applied limitations and dependencies, designs the system parameters so that the optimized SNR is achieved.
Hojat Ghassemi; Mohammad Nadafi – Pour Meibody; Keyvan Shaabani; Isa Asghari; Ebrahim Zanjirian
Volume 5, Issue 4 , January 2013, , Pages 19-28
Abstract
The application of the hydrogen peroxide as the oxidizer of a HTPB-based prototype hybrid motor is investigated in this paper. First of all, by studying the thermochemical characteristics of the propellant,operation range of different compositions is defined. A prototype hybrid motor is then designed ...
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The application of the hydrogen peroxide as the oxidizer of a HTPB-based prototype hybrid motor is investigated in this paper. First of all, by studying the thermochemical characteristics of the propellant,operation range of different compositions is defined. A prototype hybrid motor is then designed and manufactured, which is able to produce 10 kg propellant thrust. Conducting a special procedure available stabilized commercial hydrogen peroxide is processed and converted to a 90% density propellant which has less than 15 ppm tainting. A catalytic igniter is used in order to fire the motor. It was observed that the approach of employing the oxidizer to the catalyst bed is highly effective on the quality of the system performance. So, the injection quality of the oxidizer was investigated for different mass flow rates. The performance of the hybrid motor by HTTPB fuel is studied in a successful experimental test. The results of the test including the pressure and characteristic velocity are compared with the predicted theoretical simulations. Moreover, the performance specifications of the motor like the regression rate are determined and compared with the similar researches.
Hamed R. Najafi; Esmaiel Moeini; Seyed Mohammad Hossein Karimian; Hamed Alisadeghi
Volume 8, Issue 1 , April 2015, , Pages 19-25
Abstract
The intention of this paper is to discuss the results obtained from tests conducted at Amirkabir University of Technology Thermal Control Lab on multilayer insulation (MLI) blankets designed and fabricated in university, describing the thermal performance of test specimens at different environmental ...
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The intention of this paper is to discuss the results obtained from tests conducted at Amirkabir University of Technology Thermal Control Lab on multilayer insulation (MLI) blankets designed and fabricated in university, describing the thermal performance of test specimens at different environmental temperatures. We have evaluated the MLI performance by experimentally measuring our MLI’s emissivity factor. For this purpose we have defined our experiments based on the effective emissivity model. Fabricated MLI blankets are tested in a vacuum chamber at an approximate pressure of 10-6mbar and temperatures of approximately 30°C and -70°C, while subjected to heat with the power input in the range of 1.0 to 2.5 Watts. Results show that the measured effective emissivity is within the range of other reported experimental data.
Hossein Tahmasbi; Majed Lashkanpour; Abolfazl Maleki
Volume 8, Issue 2 , July 2015, , Pages 19-26
Abstract
Preliminary orbit determination of unknown space object such as satellites that are launched by other countries, military satellites and uncatalogued Space debris is important in space activities. So by means of information of ground based electro-optics systems, orbital elements of satellite can be ...
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Preliminary orbit determination of unknown space object such as satellites that are launched by other countries, military satellites and uncatalogued Space debris is important in space activities. So by means of information of ground based electro-optics systems, orbital elements of satellite can be estimated accurately. In this paper we studied most famous three methods of classical orbit determination analytically which are based on angles-only observations of orbit. Then, by using observable data and simulations, results of computational codes of three methods are compared and the effect of time separation between observed points of satellite path is demonstrated and results are analyzed.Â
Ramin Kamali Moghadam; Mohammad Reza Salimi
Volume 8, Issue 4 , January 2016, , Pages 19-27
Abstract
An accurate and efficient computational procedure is developed to predict the laminar hypersonic flowfield for both the perfect gas and equilibrium air around the axisymmetric blunt body configurations. To produce this procedure, the boundary layer equations utilize the integral matrix solution algorithm ...
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An accurate and efficient computational procedure is developed to predict the laminar hypersonic flowfield for both the perfect gas and equilibrium air around the axisymmetric blunt body configurations. To produce this procedure, the boundary layer equations utilize the integral matrix solution algorithm for the blunt nose and after body region by using a space marching technique. The integral matrix procedure enables us to create accurate and smooth results using the minimum grid in the boundary layer and to minimize the computational costs. This algorithm is highly appropriate for the design of hypersonic reentry vehicles. The effects of real gas on the flowfield characteristics are also studied in boundary layer solutions. Comparisons of the results with experimental data demonstrate that accurate solutions are obtained.
Hadi Hosseini Onari; ehsan maani; Vahid Bohlouri; Soheil Seyedzamani
Volume 10, Issue 4 , March 2018, , Pages 19-28
Abstract
In this study, hardware in the loop (HIL) simulation consisting of solar array simulator, programmable electric load, charger board, distribution board and attitude and position simulator is designed and developed for the mentioned purpose. Because of satellite high angular velocity ...
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In this study, hardware in the loop (HIL) simulation consisting of solar array simulator, programmable electric load, charger board, distribution board and attitude and position simulator is designed and developed for the mentioned purpose. Because of satellite high angular velocity in de-tumbling mode, it is not possible to perform the experimental tests for power consumption analysis. Electricalpower HIL can be used for modifying, redesigning, and verification of the electricalpower subsystem design. The power consumption of communications satellite components is simulated in a de-tumbling mode. De-tumbling mode of operation is implemented in HIL test bed and the experimental results are extracted. The results consisting of battery voltage, battery capacity, current, depth of discharge and voltage stability are investigated. The results of this paper can be useful in the design, implementation and verification of electrical power subsystem for a wide range of satellites from LEO to GEO.
M. Mirshams; H. Karimi; H. Naseh
Volume 1, Issue 1 , September 2008, , Pages 21-36
Abstract
The principle goal of this paper is developing of Launch Vehicle Conceptual Design (LVCD) method based on combinational optimization of major design parameters. To this end, ten sub-algorithms will be presented in this design approach. Mass distribution of different stages to launch maximum payload mass ...
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The principle goal of this paper is developing of Launch Vehicle Conceptual Design (LVCD) method based on combinational optimization of major design parameters. To this end, ten sub-algorithms will be presented in this design approach. Mass distribution of different stages to launch maximum payload mass to the orbit, pitch program trajectory to get to the maximum final velocity, and providing minimum velocity loss due to gravity, and also minimum axial acceleration of various stages of launch vehicle will be optimized as the results of the presented approach. The optimization process is performed subject to the restrictions. Also, the performance index is optimized in a mutual iteration mechanism. Evaluation and verification of the presented method is performed using available data of two and three-stage launch vehicles.
