• GOTO Satoru, TAKAHASHI Shinsuke YAMADA Takeshi, YAMADA Takayuki

The 28AG engine was developed since the market requires higher efficiency gas engines. As a result, 47.6% power generation efficiency, which is the highest in the world, was confirmed. Since the micro pilot ignition system, which this engine has adopted, can obtain powerful ignition energy, quick positive combustion of fuel-air mixture is enabled. Thereby, about the same high power generation efficiency and high output as a diesel engine can be obtained. The key points of highest power generation efficiency achievement are the original ignition system, adoption of the Miller cycle, optimization of pre-combustion chamber specification, optimization of fuel-air mixture formation process, and others.

• MURAKAMI Hiroki, SONEHARA Mitsuharu OIKAWA Toshinori, BANNO Hajime, TATEISHI Jun

We propose a new type mobile robot, "IMR-Type 1" which is able to move around indoors efficiently. The prototype robot is a leg-wheeled type with 3 legs and 4 pairs of wheels on the tip of each leg. The robot can move using the wheels on a flat floor and walk using the legs to go up and down stairs or to move over a small groove or step. This paper describes the concept and mechanism of this robot, its developed distributed control system using CAN (Controller Area Network), and the results of practical tests to evaluate the use and reliability of this robot system, conducted at the Prototype Robot Exhibition set up at the 2005 World Exposition Aichi, Japan.

• MATSUDA Kazutoshi, TOKUSHIGE Masafumi IWASAKI Tooru

This paper gives the results of research on Reynolds number effects on steady and unsteady aerodynamic forces on twin-box bridge section models of different scales in three different wind tunnels. The forces were measured over a wide Reynolds number range from 1.1 × 10⁴ to 1.5 × 10⁶ based on the dimension of deck height. In order to investigate Reynolds number effects on the steady and the unsteady aerodynamic forces, wind-induced static displacement analysis and flutter analysis were carried out for a suspension bridge with a main span of 2 500 m using a three-dimensional analytical model. Also, the paper considers amplitude effects on both the unsteady aerodynamic forces and the predicted flutter speeds.

• YAMAUCHI Hiroshi, HAYAKAWA Hirohisa SUZUKI Shigeru

Three dimensional carbon fiber reinforced carbon (3DC/C) composites have been used for rocket motor nozzle parts and other applications requiring heat-resistant properties for about ten years. We have developed two types of fabrication process of 3DC/C, the HIP carbonization process, and the large nozzle 3DC/C fabrication process. 3DC/C manufactured from these fabrication techniques has been applied for the C/C rocket nozzle throat. 3DC/C composites have another important characteristic of low thermal expansion. Three dimensional composites with extremely low thermal expansion properties have been newly developed by utilizing the thermal characteristics. This paper reports fabrication processes and properties.

• FUKUSHIGE Shinya, AKAHOSHI Yasuhiro, KITAZAWA Yukihito, GOKA Tateo

An accurate estimation of the impact flux of debris, the relative impact velocity and impact angle is necessary for the design of reliable spacecrafts. Space agencies of some countries have space debris environment models that can estimate debris flux as a function of the size, relative impact velocity, and impact angle in a spacecraft orbit. However, it is known that calculation results of models are not always consistent with each other. In the present, since the result of the influence estimation for debris impact depends on the selection of debris environment model, collective reliability cannot be ensured when a spacecraft is designed. Therefore, an internationally common implementation process for debris environment models is required and the proposal for the international standard is being prepared in Japan. In this paper, as the first step of the international standardization of the implementation process of debris environment models, we compared estimation results of debris impact flux in low Earth orbit calculated by the available three debris environment models, namely NASA's ORDEM2000, ESA's MASTER2001 and MASTER2005. The results display that a large difference in flux estimation appears in size of debris > 100 um and > 1 mm.

• SEKIYA Takao, ODA Yoshio

• ARAI Hiroyuki