Experimental studies on ram accelerator starting processes were conducted using a 25-mm-bore ram accelerator installed at Shock Wave Research Center, Institute of Fluid Science, Tohoku University. Necessary starting conditions for the thermally choked propulsive mode are discussed on. Ram acceleration was realized, yielding a velocity gain of 350m/s. Shock heating processes before and during diaphragm rupture by a projectile were visualized by high-speed photography, thereby supporting a conclusion made by Burnham that the shock-heated slug can play as an ignitor to the mixture.
In this paper, we describe the results of the Japan-USA international joint research on “Super-long-distance space telerobotics.” An experimental study of space structure assembly by a far-distant robot was conducted. Handling a deployable truss with flexible structure and measures to cope with a low communication rate and long time delay are dealt with for space structure assembly by the telerobot. Furthermore, the technology of interoperation of space robots by internationally distributed users through a communication network of public phonelines and the Internet are studied. An intelligent telerobotic system integrated by a man-robot cooperative function with an object-handling knowledge base and an intelligent monitoring function was developed. A Trans-Pacific experiment between Electrotechnical Laboratory in Japan and Jet Propulsion Laboratory in US was achieved to demonstrate the effectiveness of the telerobotic system using a ground testbed.
The classical wall correction method for aerodynamic data of a wing or a complete airplane model obtained in a typical model to test section size ratio low-speed wind tunnel was found to be inadequate when compared thecorrected data with the respective model's free air characteristics. It was found that in due process of data reduction by the classical blockage correction method, the induced drag which was not corrected for the wall interference had been computed and used. An equation was derived to apply wall induced upwash correction to the induced drag, and a new blockage correction method was developed. Experimental verifications demonstrated that the present method provided a better agreement of the wind tunnel wall corrected data with those of the free air than the classical results, proving a higher level of correction accuracy of the present method.
Recently, focus has been placed on the development of mobile communications and broadcasting systems using GEO satellites. To realize these systems, a development of a beam synthesis technology for the satellite antennas is a matter of great importance, so that several design methods such as antenna gain optimization have been reported. However, no design considering the radiation characteristics of the mobile antenna has been reported. This paper describes a beam synthesis method which can compensate for the radiation characteristics in the elevation angles of the mobile antenna. The shaped beam by using this method makes it possible to provide uniform service quality throughout coverage area of the systems, because the beam shape on the satellite and mobile antenna are just the opposite. We will first present this method, and its shaped beams with an offset parabolic antenna which uses a 13-element feed. These shaped beams designed for a switching planer array antenna composed of 12 circular microstrip antenna elements which are arranged to form a cross so that we could obtain a simple tracking mechanism. We will then present a new feed system using a Hybrid Matrix Amplifier.