Research Paper
Hadiseh Karimaei; Ramin Ghorbani; Seyed Mostafa Hoseeinalipour
Volume 11, Issue 4 , December 2018, Pages 1-10
Abstract
In the atomization process, small disturbances grow in liquid jet or sheet and eventually cause to disintegrate it into ligaments and smaller droplets. Concerning to the motion of waves on the liquid sheet surface, the stage of primary breakup is deterministic and can be predicted by instability analyzes. ...
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In the atomization process, small disturbances grow in liquid jet or sheet and eventually cause to disintegrate it into ligaments and smaller droplets. Concerning to the motion of waves on the liquid sheet surface, the stage of primary breakup is deterministic and can be predicted by instability analyzes. In early studies, the theories of linear and weakly nonlinear instability have been implemented on a cylindrical liquid sheet and the effect of spray cone angle was not included in the model. Therefore, in this paper in order to improve the model, the linear instability theory is implemented on a cone-shaped liquid sheet for the first time, and therefore radial velocities of liquid and gas phases are also considered moreover than axial and tangential velocities. The results of this improved model such as maximum wave growth rate and its corresponding wave number can be used to estimate mean droplet diameter and breakup length.
Research Paper
M. Navabi; A. Davodi
Volume 11, Issue 4 , December 2018, Pages 11-22
Abstract
Sloshing phenomenon in spacecraft fuel tank during orbital maneuver, causes adverse effects on spacecraft attitude. Therefore, before orbital maneuvers, modeling fuel sloshing and determining appropriate method for controlling it has to be carried out. The aim of this paper is to model slosh dynamics ...
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Sloshing phenomenon in spacecraft fuel tank during orbital maneuver, causes adverse effects on spacecraft attitude. Therefore, before orbital maneuvers, modeling fuel sloshing and determining appropriate method for controlling it has to be carried out. The aim of this paper is to model slosh dynamics by using double pendulum model in two-dimensional space. Spacecraft maneuver and pendulums motion are considered in 2D-coordinate, so coupled spacecraft and pendulums dynamic system are 5 degrees of freedom systems. Here, linear control methods (PD and LQR), and also nonlinear control methods (Lyapunov and fuzzy) are determined to stabilize dynamic parameters of the introduced system. Simulation results show that designed controllers have good performance to achieve stabilization of the parameters.
Research Paper
Behzad Mohasel afshari; Javad Haghshenas; Mohsen Abedi; Masoud Khoshsima
Volume 11, Issue 4 , December 2018, Pages 23-30
Abstract
In this paper, a precise method for calculating albedo and IR heat flux applied to a satellite is presented. For obtaining albedo heat flux applied to a satellite, a point on the earth’s surface that sun flux reflected at that point and reach to the satellite is obtained, hence albedo heat flux ...
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In this paper, a precise method for calculating albedo and IR heat flux applied to a satellite is presented. For obtaining albedo heat flux applied to a satellite, a point on the earth’s surface that sun flux reflected at that point and reach to the satellite is obtained, hence albedo heat flux reaches to a satellite is obtained as a function of longitude, attitude and longitude. IR heat flux is integration of emitting heat flux for points on the earth surface that in satellite’s view. Atmospheric transparency for calculating albedo and IR heat is considered for sun light and IR spectrum using MODTRAN algorithm using PcModWin software. For a generic LEO satellite, IR and albedo heat fluxes are calculated at a time period and compare with reference values. Obtained heat fluxes are used to obtain temperature variation of satellite’s components during its mission.
Javad Shams; Jafar Roshanian
Volume 11, Issue 4 , December 2018, Pages 31-42
Abstract
In this paper, an analytical solution to deflection mission of asteroid as potentially hazardous spatial mass that threat humanity in future is investigated . The mission of deflecting potentially hazardous asteroids in recently years with possibility of their collision with Earth and the priority to ...
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In this paper, an analytical solution to deflection mission of asteroid as potentially hazardous spatial mass that threat humanity in future is investigated . The mission of deflecting potentially hazardous asteroids in recently years with possibility of their collision with Earth and the priority to carry out the mission of mitigate risk of these objects from its original space trajectory in recent years has been studied with interest in scientific research. Different methods have been proposed for execute the deflecting these celestial objects, among which the use of gravity tractor technology has become more widely used. In addition, the increasing use of formation flying technology in space missions is increasingly increasing, which has led to the use of this technology in this survey.
erfan beygi; Amirhossain Adami
Volume 11, Issue 4 , December 2018, Pages 43-50
Abstract
Basically, it takes alot of time to analyze structures with different parameters, depending on the type of structure and parameters. Also, by changing any parameter, all the analysis process must be repeated. Therefore analyze the effect of different parameters on the behavior of structures, many analyzes ...
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Basically, it takes alot of time to analyze structures with different parameters, depending on the type of structure and parameters. Also, by changing any parameter, all the analysis process must be repeated. Therefore analyze the effect of different parameters on the behavior of structures, many analyzes should be carried out that are time consuming. The results obtained are valid only for the same parameters, and are not valid by changing the parameters. In this research, a Nested dependence method has been developed that can be used to determine the behavior of the structure with proper accuracy with short time. In this method, first an interval is considered for different parameters of the structure. Then, by using the finite element analysis method and applying the loading and boundary conditions, the behavior of the structure. By repeating this process to extract the appropriate number of input data, a Nested dependence method can be used to estimate the structure behavior of different inputs.
Research Paper
Hamid Kazemi
Volume 11, Issue 4 , December 2018, Pages 51-64
Abstract
Because the lack of international regulations for exploiting the sources of celestial bodies, so some countries, such as the United States and Luxembourg, start to support the private sector, and to regulate and monitor their activities. , Have adopted a special national law that legislate that the appropriation ...
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Because the lack of international regulations for exploiting the sources of celestial bodies, so some countries, such as the United States and Luxembourg, start to support the private sector, and to regulate and monitor their activities. , Have adopted a special national law that legislate that the appropriation of what is achieved by the private sector from natural sources of celestial bodies is not conflicting with international regulations. While the prevailing view is that the adoption of national laws on the use of celestial bodies as well as their sources contrary to the appearance of international on the Prohibition of Ownership and appropriation of the Moon and the celestial bodies and the principle of the common heritage of mankind. By analyzing current international space legal instruments such as the Outer Space Treaty 1967 and the Moon Agreement1979, the Article seeks to bring two perspectives together and propose an international regime governing the private sector's activity.
