Research Paper
Hadiseh Karimaei; Mostafa Hossein Alipour; F Ommi; Ehsan Movahednejad; Reza Sharifzadeh
Volume 10, Issue 4 , March 2018, Pages 1-7
Abstract
A swirl injector is tested to investigate the instability of the liquid sheet emanating from it and determine the main microscopic characteristics of the spray. The injector, which is tested, was already approved by doing the characterization tests (macroscopic). Due to the fact that the PDPA systems ...
Read More
A swirl injector is tested to investigate the instability of the liquid sheet emanating from it and determine the main microscopic characteristics of the spray. The injector, which is tested, was already approved by doing the characterization tests (macroscopic). Due to the fact that the PDPA systems to measure the spray characteristics are very expensive and high-tech, and therefore inaccessible for us , it is attempted to investigate the specifications and instability of the liquid sheet as much as possible, by photography. The liquid sheet emanating from the injector has perturbations on its surface which originate from inside the injector. Due to the aerodynamic interactions, these perturbations grow and eventually lead to break up the liquid sheet and form the ligaments. The growth of these unstable waves can be observed in the images. Also the breakup length can be measured using the images recorded. Also ligaments in the primary breakup zone and droplets were shown.
Research Paper
Alireza Sharifi; Mahdi Foroughi; H. Nobahari
Volume 10, Issue 4 , March 2018, Pages 9-17
Abstract
In this paper, an adaptive-neuro-fuzzy controller is implemented online for a temperature control system using model-based design. First, the time domain identification approaches are utilized for the dynamic model identification. Then, the identified model is used in the adaptive-neuro-fuzzy controller. ...
Read More
In this paper, an adaptive-neuro-fuzzy controller is implemented online for a temperature control system using model-based design. First, the time domain identification approaches are utilized for the dynamic model identification. Then, the identified model is used in the adaptive-neuro-fuzzy controller. The simulated model of the proposed controller, created in the Simulink environment, is translated into C code using Simulink Coder. The generated C code is compiled into a hardware device and is successfully embedded on a microcontroller. In the next step, the experimental setup of a temperature controller is done to verify the adaptive-neuro-fuzzy controller. Finally, a comparison was made between the proposed controller and a classical proportional-integral-derivative controller to investigate the performance of the proposed approach. The results demonstrate that the proposed approach provides an excellent performance for a temperature control system.
Research Paper
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 ...
Read More
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.
Research Paper
atefeh hoseinzadeh; Amirhossain Adami; Asghar Ebrahimi
Volume 10, Issue 4 , March 2018, Pages 29-40
Abstract
The atmospheric re-entry phase is one of the most significantmission steps in the space missions;hence, theguidance and control of reentry vehicles in this phase of mission is important. In this article, a reentry vehicle guidance algorithm has been proposed which has suitable robustness in the presence ...
Read More
The atmospheric re-entry phase is one of the most significantmission steps in the space missions;hence, theguidance and control of reentry vehicles in this phase of mission is important. In this article, a reentry vehicle guidance algorithm has been proposed which has suitable robustness in the presence of initial reentry parameters uncertainties. Here,it has been tried to minimize the landing errors at terminal point using Nonlinear Quadratic Tracking (NQT) and chasing a reference trajectory. In order to define several trajectories with different initial states using evolutionary genetic algorithm with changes in weighting matrices Q and R, it hasbeen tried to reduce the errors of landing at terminal point. The reentry position of the reentry vehicles may be different from the desired ones with respect to several events. In this situation, reentry vehicles start to move in a new trajectory which is not suitable. Therefore, the reentry vehicles should be guided to come back into the desired trajectory or a new optimum trajectory needs to be redesignedto have the same target position on the ground. To do this, we need optimum weighting matrices R and Q for every new trajectory. In this article, this problem has been resolved using partial least squares regression; meanwhile, obtaining the optimal matrices by genetic algorithms needed many times. Also,it is shown that using this method, in the presence of reentry uncertainties, weighting matrices for each new initial condition hasbeen quickly derived. Additionaly,through the matrices obtained and the nonlinear quadratic tracking controller, reentry vehicle was directedto the target with a good accuracy. The Monte Carlo analysis has been used to evaluate the performance of the proposed algoritm. According to the results, the proposed algoritm has a suitable accuracy level and it can generate the online optimum trajectory.
Research Paper
Zeynab Aghajani; Ehsan Zabihian; Mehran Mirshams
Volume 10, Issue 4 , March 2018, Pages 41-54
Abstract
The significance and the wide use of geostationary communication satellites and the long hours of work in the process of their conceptual design was the main motivation to develop a software based on the statistical design to reduce the time spent on the conceptual design phase. This software is based ...
Read More
The significance and the wide use of geostationary communication satellites and the long hours of work in the process of their conceptual design was the main motivation to develop a software based on the statistical design to reduce the time spent on the conceptual design phase. This software is based on the statistical and parametric design method. The statistical model used in this software includes a database of 147 satellites launched between 2010 and 2016. To increase the accuracy of the software, the combined parametric model has been used from selected design references. The software is based on MATLAB and to make it more user friendly, the graphical GUI was used. In this article, the design of the software is presented and there is focus on the design and verification method. The accuracy of this tool was amply verified through a flight prototype, indicating the average error of 16% in the obtained results.
Research Paper
Vahid Bohlouri; S.H Jalali-Naini
Volume 10, Issue 4 , March 2018, Pages 55-66
Abstract
his paper suggests arobust optimization algorithm for the design of the satellite attitude control system in order to increase the robustness of the performance under uncertainties. A single-axis on-off attitude control with rigid dynamics is considered using Schmitt-Trigger and PID controller. The model ...
Read More
his paper suggests arobust optimization algorithm for the design of the satellite attitude control system in order to increase the robustness of the performance under uncertainties. A single-axis on-off attitude control with rigid dynamics is considered using Schmitt-Trigger and PID controller. The model uncertainties include the moment of inertia, thrust level, thruster delay and theexternal disturbance amplitude.A weighted combination of expected value and standard deviation of pointing error is considered as an objective function for the robust optimization. The numerical solutions show that the robust optimization reduces the variations of the objective function, i.e. it increases the robustness of the system performance compared to the deterministic optimization.
