The effects of the moon resource (3He) exploitation on the earth ecological and economics system are studied by a system dynamic simulation. The simulation indicates that the shortage of the energy resource on the earth can be resolved and the population on the earth can be grown into the number twice as large as the present one without increasing the pollution (CO2 in the atmosphere) and seriously spoiling the quality of life during the next 500 years by using 3He on the moon. The simulation also suggests that the discard rate of the capital investment on the moon has to be as small as possible to take the advantage of the 3He exploitation.
This paper describes designs of the gust load alleviation (GLA) system and its wind-tunnel tests. The objective is to verify the effectiveness of control system syntheses which we have examined theoretically in the active flutter suppression (AFS). Applying the syntheses to the GLA system of a cantilevered elastic rectangular wing, the 1st or the 2nd order controllers can be constructed. It is shown in the wind-tunnel tests that the bending moment at the wing root is reduced to 66.2% of the control-off value as the best by using a designed reduced-order controller. Furthermore, the robustness for the parameter perturbation of the plant is verified in the tests where the wind velocity is 50% higher than the designed wind velocity.
The correlation between the streak line patterns visualized and the results obtained by the hot-wire probe was investigated in the wakes both behind a circular cylinder and a flat plate at zero incidence in a low-speed wind tunnel. When a smoke wire is set in a section of a vortex street, the pattern of streak lines shows the vortex street, if the circulation of each vortex is strong enough. If the circulation is weak, then the streak line pattern does not show the vortex street, but shows only wavy streak lines. The patterns of streak lines for both cases of a circular cylinder and a flat plate seem to show the downstream increase in the size of vortices. However, the vorticity of a vortex in the wake of a circular cylinder diffuses into the surroundings and its circulation decreases downstream. On the contrary, the vorticity in the wake of a flat plate concentrates gradually so that vortices are formed and their circulations increase for some downstream distance. Further downstream, they begin to decrease.
In this paper a new numerical method to solve a pressure Poisson equation with Neumann boundary conditions is presented. The Poisson equation with Neumann boundary conditions is divided into two equations. One is the Poisson equation with Dirichlet boundary conditions at the whole boundary, which can be solved by the conventional checkerboard SOR method with a reasonable convergence, and the other is the Laplace equation with boundary conditions obtained by taking the derivative of the solution so as to satisfy the Neumann boundary conditions for the original equation. The latter can be quickly solved by the BEM at least at the boundaries. The solutions at the interior points can be calculated by the BEM or solving the Laplace equation with Dirichlet boundary conditions by the checkerboard SOR method to reduce CPU time. Consequently, the solution of the original equation is obtained as the sum of each solution. This method is applied to the primitive variable procedure to solve the incompressible flow around a circular cylinder at the Reynolds number of 105, which produces a converged pressure solution at every time step and the time-averaged drag coefficient close to the experiment.
Although a pair of 5-cm diameter mercury propellant ion engines were successfully operated on Japanese Engineering Test Satellite (ETS)-III, the operational time assigned for the space mission was limited to under 500 hours. A long-life test on the ground was necessary to confirm the merits of the ion engine system. A recycle test of a hollow cathode was planned because the hollow cathode was one of the most susceptible components in the engine system. The tested hollow cathode was fabricated by the same process as the one used in ETS-III and operated with a power conditioner similar to that of the ETS-III. As a result, over 8, 000 on/off cycle tests were completed. Performance mapping was carried out, after every 1, 000th cycle, and the results plotted exhibited no degradation. Surface analysis using SEM, XMA and AES was carried out for the inner portion of the hollow cathode, which was disassembled after the test. The conclusions of the above three analyses were that no severe degradation was exhibited after the recycle test and that durability was verified for 10, 000 hours of future operation.
From the previous operational experience for the high speed cryogenic tunnel at National Defense Academy (NDA), its original manual control systems were partially modified, and a limited automatic control capability has been added. Though this modification was intended to improve the steady state operation, the control accuracy of both of the steady and transient operations was greatly improved, compared with that of the previous manual controls. The preliminary tunnel calibration tests were intensively performed at both of ambient and cryogenic temperatures, and the results indicate that the NDA cryogenic tunnel satisfied the assigned specifications, and has sufficient potential to perform basic airfoil testings in a cryogenic temperature range.