Global Positioning System (GPS) is widely utilized in daily life, for instance car navigation. Wide Area Augmentation System (WAAS) and Local Area Augmentation System (LAAS) are proposed so as to provide GPS better navigation accuracy and integrity capability. Satellite Based Augmentation System (SBAS) is a kind of WAAS and Multi-functional Transportation Satellite (MTSAT) has been developed in Japan. To improve navigation accuracy most efficiently, augmentation satellites should be so placed that minimize Geometric Dilution of Precision (GDOP) of constellation. In this paper the result of optimal constellation design for SBAS is shown.
One-dimensional numerical analyses of pulse detonation engine (PDE) have been performed by numerous workers. In one-dimensional codes, however, it is basically difficult to set adequate boundary conditions at exit plane, although PDE performance depends strongly on the boundary conditions. To evaluate the influence of boundary conditions, we performed a two-dimensional analysis for a straight single PDE, flying in an external environment under different fuel/oxidizer equivalence ratios. As a result, the physical processes in one PDE cycle and associated PDE performance are acquired.
In a previous paper, the authors presented the identification method of locations and force histories of point impacts on laminated composite flat plates by using the measured values of acceleration. This paper deals with an attempt to extend the method so as to apply to identification of point impacts on laminated composite curved panels. Numerical identification results are obtained for the single point impact and double point impacts on cross-ply laminated composite curved panels. The validity of the identification method to laminated composite curved panels is verified by comparing the identification results with exact ones. In addition, when the number of point impacts is unknown, a method to decide the identification results is proposed. Several numerical examples are considered to ascertain the validity of the proposed method.
Formation flight is a new technology which enables various missions such as high resolution interferometer, virtual antenna instead of huge antenna for a large amount of communication, etc. To realize formation flight, navigation and control of relative position and velocity among related spacecraft are necessary. ETS-VII is a test satellite to perform in-orbit demonstration of autonomous rendezvous docking (RVD) technology. ETS-VII conducted three RVD experiment flights, and flew keeping definite ranges time and again. To evaluate position control accuracy of formation flight, we analyzed flight data of ETS-VII during position keeping flight. Control accuracy depends on navigation accuracy. We present the result in this paper.
This study is concerned with a shape optimum design of a propeller blade operating in a low Reynolds number range, 1.0–2.0×105. The objective is to minimize the power-required under the constraints on the thrust and the angle of attack in terms of chord length and twist angle distributions where the power-required is evaluated by 3-D panel method. The profile drag is also considered in the optimization, because the effect cannot be ignored in a low Reynolds number range. For calculation efficiency, the profile drag coefficient is approximated by higher order polynomials in terms of Reynolds number and angle of attack. The effectiveness of the proposed method is demonstrated by the design of a propeller blade of a human-powered aircraft. Additionally, effect of the profile drag is discussed by comparing the designs with and without considering the profile drag.
This note presents an order-n formulation for two-dimensional dynamics of multibody attached with flexible beams. The present formulation is a modified version of Rosenthal’s algorithm so that flexible beams on bodies can be treated. A flexible beam in the present note is assumed to be a cantilever attached on a rigid body. The formulation can handle the tree topological configuration for the multibody but cannot treat the closed topological configuration nor the situation where flexible beams are connected with each other. This note shows a method for implementing the present algorithm as Simulink C-Mex S-function, and also shows that operation time for modifying the model and simulation is reduced due to the present implementation.
A two-dimensional blunt body was submerged in a compressible turbulent boundary layer and the surface pressure was measured. It was found the fore-body drag was reduced due to the velocity defect in the boundary layer and the associated re-circulation behind an oblique shock wave. A small two-dimensional shock generator ahead of the blunt body further reduced the drag of the blunt body.