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In order to evaluate our developing 3D directional borehole radar system, ReflexTracker®, we carried out experimental studies on its capability to detect foundation piles in poor subsoil in the Tokyo area, and cavities beside a housing complex in Aichi Prefecture, central Japan. To evaluate foundation pile detectability, we took omnidirectional and directional borehole radar measurements in two boreholes...
Borehole radar is widely used in civil engineering work such as fault and fracture exploration, salt dome investigation, tunnel detection, UXO detection, exploring locations of foundation piles and sheet metal piling walls, and so on. Borehole radar surveys in resistive rock field have been applied successfully due to the lower attenuation of the rock media. Through those studies, many researchers...
The Multiple Signal Classification (MUSIC) algorithm is modified in order to resolve multiple waves and to estimate reflection points in 3-D space. This algorithm is suitable for directional borehole radar with a circular dipole array antenna. Making use of the spatial frequency difference of acquired array signals, the signals are decorrelated, and the 3-D MUSIC algorithm is applied. The time domain...
This paper describes a new directional borehole radar system and its field testing. The system uses a thin radar probe (57 mm diameter) and a circular dipole array directive antenna. The radar is of the step frequency type with a network analyzer. Through careful antenna design, we were able to achieve the compact radar probe and precise measurement at frequencies between 5 and 500 MHz. All the associated...
This paper proposes an architecture that realizes a VPN interconnection system that forms on-demand connections between multiple VPN users. When constructing VPN interconnections, the VPN endpoint configurations and the router's configuration data necessary to route between VPN endpoints are dependent on the underlying network architecture. Furthermore, the design of configuration data for VPN endpoints...
The base material currently used for optical fiber waveguides (optical fibers) is silica. By adding various impurities, properties required for optical transmissions are created. When these optical fibers are used in a particular environment, such as a nuclear reactor, damage caused by radiation from the source becomes a serious problem. It is well-established that when optical fibers are exposed...
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