We have proposed mobile multimedia satellite communication system designed to realize high-speed multimedia communications. This system uses a mobile network for the return link and the developed satellite-tracking antenna that receives high-speed satellite signals for the forward link. The satellite-tracking antenna, which consists of four planar antennas, measures the pointing error by the phase monopulse and has achieved the satellite-tracking control by the co-phasing combining and the mechanical drive. When the satellite-tracking antenna is applied to the car and the ship, it is necessary to decide the tracking drive angle constantly. When it is applied to the train, the satellite-tracking can be expected to be achieved by specifying the tracking drive angle in accordance with the distance because the train runs in the same route. This tracking method is called a program tracking in this paper. This paper describes the tracking drive angle and the error factor of the program tracking quantitatively. We concluded that it was possible to apply the program tracking to the train if operating rate of the system was 70% or less.
The data from a series of low-velocity collision experiments performed at Kyushu University will be re-analyzed based on the method used in the National Aeronautics and Space Administration (NASA) standard breakup model 2000 revision to be compared with the hypervelocity collision model adopted in the NASA standard breakup model. The results will indicate that the NASA hypervelocity collision model can be applied to low-velocity collisions possible in the geosynchronous regime with some simple modifications.
In this paper, we propose a new adaptive grid generative method on unstructured grid system for unsteady compressible flows. For unsteady adaptive grid generation, it is important to assure geometric conservation laws on moving grid system according to motion of flow solution. To solve the issue, we adopt volume integration to a control volume on the space-time unified domain. That is, we apply a finite volume method on a moving grid. While, unstructured grid system is flexible and suitable for flows with complex boundary. Thus, an adaptive grid generation method and the moving-grid finite-volume method are combined and developed on unstructured grid system. The method is described for two-dimensional flows and validated using simple test problems. Application to shock-tube problem and supersonic duct flow problem have shown a promising feature of the method.
Numerical simulation method for the prediction of supersonic intake performance is discussed. To perform a practical simulation, it is necessary to consider not only the nacelle-only configuration but also the engine/airframe configuration. In this study, the unstructured mesh, known to have advantages with regard to adaptation to complex geometry, was generated around aircraft geometry and the Euler equation was solved. To obtain higher numerical accuracy for the shock wave/boundary layer interaction, which appears at the inlet, the structured Navier-Stokes solver was applied to solve flows inside the flow-through nacelle. These regions were coupled with using the unstructured-structured zonal approach. The nacelle-only configuration and the engine/airframe configuration were calculated using this method and the effects of the airframe existence on supersonic intake performance were investigated.
Structural health monitoring of cracked aircraft structural panels repaired with bonded FRP composite patches has received wide attention to extend service life of aging aircraft. In this paper is presented the method to identify the location and shape of a fatigue crack front in aircraft structural panels repaired with a bonded FRP composite patch by use of a tunneling method. As measured values, strains on a measurement plane in the FRP composite patch are utilized. Several numerical examples of the identification of location and shape of fatigue crack fronts are examined, and the effects of number of strain measurement points, position of a strain measurement plane and measurement errors of strains on the identification results are discussed. The validity of the present identification method is verified by comparing the identification results with the exact ones.
A Multi-Objective Genetic Algorithm (MOGA) is applied in search of the optimal fuel injector shape in the supersonic combustor. The optimal shape is investigated in terms of rapid mixing of fuel jet and supersonic airstream. Two goals, those are to maximize the jet core height and to minimize the total pressure loss, are adopted for the optimization. The numbers of maximum injector holes are restricted to 1, 2 and 3 during the evolutive process. Pareto fronts under the 2 and 3 maximum holes restriction evolve successfully. Self-Organizing Map (SOM) is applied, in order to realize the role of optimal solutions in actual design, to analysis of structure on design space by means of design database obtained in evolutive process of optimization. The design database is mapped onto the two-dimensional SOM, where design space is successfully visualized. The visualization that clarifies relativity of performance parameters acquires valuable design information.
Contiguous-ply cracking behavior induced by existing transverse cracks in composite laminates is investigated. When transverse cracks occur and accumulate in one ply, matrix cracking in contiguous plies is induced one after another. In this study, stress analytical method of laminates with obliquely-crossed transverse cracks (e.g. [S/θm/90n]s laminates with transverse cracks in θ- and 90-plies) is presented and combined with finite element analysis, which enables geometrically parametric analysis using a single discrete model. Stress analyses of [0/θ2/90]s laminate with cracks in θ- and 90-plies are performed under various conditions of angle θ and θ-ply crack length. Moreover, energy release rates associated with θ-ply crack propagation are calculated. These results suggest that presence of 90-ply cracks affects θ-ply crack propagation in fiber direction, especially through mode-I energy release rates, depending on angle θ. The formation of 0-ply cracking in [0/θ2/90]s laminate with cracks in θ- and 90-plies is also discussed.