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1. Satellite Conceptual Design Multi-Objective Optimization Using Co Framework
دوره 7، شماره 1 ، فروردین 1393
چکیده
This paper focuses upon the development of an efficient method for conceptual design optimization of a satellite. There are many option for a satellite subsystems that could be choice, as acceptable solution to implement of a space system mission. Every option should be assessment based on the different criteria such as cost, mass, reliability and technology contraint (complexity). In this research, mass and technology constraints, which have a direct impact on the satellite life cycle cost, are considerd as system level objective function to obtain the system optimal solution during the coceptual ... بیشتر2. Effects of Some Parameters on Thermal Control of a LEO Satellite
دوره 7، شماره 1 ، فروردین 1393
چکیده
Satellite thermal control ensures safe operating temperature ranges for satellite components throughout the mission life. Effects of altitude, spin, and position of satellite radiator(s) on the thermal control of a small Low Earth Orbit (LEO) satellite have been studied. Results show that change in satellite altitude, in the range considered here, does not produce critical thermal conditions. However, satellite spin rate has a marked influence on the satellite temperatures. Also, comparison of results for the satellite configurations considered in this study suggests that a radiator at top provides ... بیشتر3. Reliability Determination of a Sounding Rocket Separation System Using its Reliability Block Diagram and FMEA
دوره 7، شماره 1 ، فروردین 1393
چکیده
Separation system is one of the most important systems in rockets. The influence of this system on mission success cannot be ignored. In this paper, reliability of a sounding rocket separation system is determined using block diagram and FMEA . This system is based on the flexible linear shape charge cross-section and a spring mechanism to accelerate separation. In this investigation, the reliability block diagram of the separation system including mechanical and electrical mechanisms is determined. By considering reliability of each component based on expert opinion and using separation system ... بیشتر4. Laminar and Turbulent Aero Heating Predictions over Blunt Body in Hypersonic Flow
دوره 7، شماره 1 ، فروردین 1393
چکیده
In the present work, an engineering method is developed to predict laminar and turbulent heating-rate solutions for blunt reentry spacecraft at hypersonic conditions. The calculation of aerodynamic heating around blunt bodies requires alternative solution of inviscid flow field around the hypersonic bodies. In this paper, the procedure is of an inverse nature, that is, a shock wave is assumed and calculations proceed along rays normal to the shock. The solution is iterated until the given body is computed. The inverse method is practical for the calculation of flow field between the shock wave ... بیشتر5. Approximate Viscous Shock-Layer Analysis of Axisymmetric Bodies in Perfect Gas Hypersonic Flow
دوره 7، شماره 1 ، فروردین 1393
چکیده
In this paper, an approximate axisymmetric method is developed which can reliably calculate fully viscous hypersonic flow over blunt-nosed bodies. In this method, a Maslen’s second-order pressure expression is used instead of the normal momentum equation. The combination of Maslen’s second-order pressure expression and viscous shock layer equations is developed to accurately and efficiently compute hypersonic flow fields of perfect gas around blunt-body configurations. The results show that, this combination leads to more accurate solutions and less extensive computer run times in the ... بیشتر6. Fuzzy Sliding Mode for Spacecraft Formation Control in Eccentric Orbits
دوره 7، شماره 1 ، فروردین 1393
چکیده
The problem of relative motion control for spacecraft formation flying in eccentric orbits is considered in this paper. Due to the presence of nonlinear dynamics and external disturbances, a robust fuzzy sliding mode controller is developed. The slopes of sliding surfaces of the conventional sliding mode controller are tuned according to error states using a fuzzy logic and reach the pre-defined slopes. The controller is designed based on the nonlinear model of relative motion and perturbation and atmospheric drag are considered as external disturbances. Using the Lyapunov second method, the stability ... بیشتر7. FPGA Implementation of JPEG and JPEG2000-Based Dynamic Partial Reconfiguration on SOC for Remote Sensing Satellite On-Board Processing
دوره 7، شماره 1 ، فروردین 1393