Power-source stabilization methods such as measures against voltage drop, power loading fluctuation and regenerative power lapse represent important issues in DC railway-feeding circuits. Providing an energy storage medium that uses power efficiently and reduces the problems mentioned above is therefore a major concern. The development of such a medium has attracted public interest, with several energy storage applications (including batteries and flywheels) already having been investigated. A wide range of large-scale electric double-layer capacitors [EDLCs] that are rapidly charged and discharged have been developed, and offer durability, maintenance-free features, low-pollution and high efficiency. For their fundamental study, we produced a prototype DC electrified railway energy storage system consisting of EDLCs, a diode bridge rectifier, a chopper system and a pulse-width modulated [PWM] converter, with useful information obtained from charge/discharge tests. Based on these results, two energy storage systems were built for DC 600 V and DC 750 V, and verification tests were conducted in conjunction with the Enoshima Electric Railway Company Ltd. and the Osaka Municipal Transportation Bureau. It was confirmed through verification tests that energy storage using electric double-layer capacitors provided effective functions to DC 600V and DC 750V railway systems. The tests proved to be a guideline for actual application in DC 1,500V or DC 3,000V railway systems.

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Aluminum-based rigid conductor lines have been widely installed in tunnel sections due to a cost-saving factor and their lightweight structure. Aluminum, however, is easily corroded, it is therefore important to understand the corrosive characteristics of aluminum under the practical environment. The authors carried out an accelerated corrosion test with alkali water and saltwater spraying tests to measure the material characteristics of corrosion. The results of these tests are described in this paper, and the authors have indicated the predicted lifetime of aluminum based under the various environments.

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A simple catenary with copper-steel contact wire is one of overhead contact lines equipped high-speed lines as Shinkansen. Local wear of the contact wires were visible at the simple catenary with copper-steel contact wire of commercial lines. In addition, the result of the investigation on this line revealed that the wear occurred at overlaps of the overhead contact line and a part of station. The authors therefore proposed a measure for local wear at the overlaps, and verified the effects on a commercial line. Furthermore, we clarified the cause of wear by monitoring the sliding surfaces of the contact wires at the stations.

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The authors are currently developing a new ATP (Automatic Train Protect) system, known as the ATS (Automatic Train Stop) system in Japan. This new system, named the "ATS-X system", is interoperable with the existing ATS-S system used on almost all Japan Railway companies' narrow-gauge lines. In this ATS-X system, a continuous surveillance pattern is generated in an on-board device using digital data intermittently transmitted from beacons. The safety level of the ATS-X system is therefore higher than that of the ATS-S system. We considered the basic functional specifications of the ATS-X system for practical use with seven JR companies. In this paper, we report on these specifications and the functional test results from the field.

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We have developed an efficient tunnel scanner with line sensor cameras capable of taking high-precision panoramic annular images of the surface of a tunnel lining at low cost. In this paper, we first describe the improvement made to the focus adjustment method, and then propose an image processing technique to remove image fluctuation. We also describe the sub-pixel-style image processing algorithm developed to extract minute cracks from a standard wall image and measure their characteristics such as width, length, direction etc. to a high level of accuracy. As a result, the overall costs have been kept down and the practicability of this detection system has made significant progress.

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Effective lightning protection measures are essential for railway signalling systems because suspended operation or train delays due to lightning damage may cause social disruption. The authors therefore measured lightning overvoltages on level crossing systems (representing typical examples of wayside signalling equipment) in the event of substantial lightning, enabling quantitative analysis of the frequency of lightning overvoltage occurrence and the collection of basic data for the consideration of countermeasures against lightning. As a result, it was possible to estimate the occurrence probability of lightning damage caused by exceeding the withstand voltage of the level crossing system.

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The current lead of a superconducting magnet (SCM) is a conductor that connects the superconducting coils to an external power supply. Since the copper alloy generally used for such leads acts as a route for heat leak to the inside of the SCM, the authors developed a high-temperature superconductor (HTS) current lead and evaluated its properties using a measuring system for the HTS current lead. The properties of this lead enable a reduction in length, and the removal of the evaporated helium gas cooling mechanism of the current lead. The advantages of this HTS current lead enable a higher level of SCM performance.

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Ground coils installed along the entire guideway length of a magnetically levitated (Maglev) transportation system need to withstand long-term outdoor use as they are vibrated by electromagnetic forces when a vehicle passes. Verifying ground coil dynamic durability under conditions of substantial electromagnetic vibration is important for ensuring the total reliability of the Maglev system. We therefore developed an electromagnetic vibration test apparatus unavoidable for the bench test. Using this apparatus, we succeeded in evaluating the dynamic durability performance of ground coils in operation.

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In the JR maglev system, trains are operated by the electrodynamic force between ground coils and on-board superconducting magnets (SCMs). When a train is running, SCMs are vibrated by the electromagnetic disturbance that occurs when the train passes over the ground coils. Such a phenomenon generates frictional heat in the SC-coil. It has been surmised that this frictional heat is caused by the relative microscopic slips between the structural components of the SC-coil. The dual aims of this study were firstly to elucidate the mechanism of frictional heat inside an SC-coil, and secondly to reduce frictional heat. A fretting test was performed at liquid-helium-cooled boundaries between the structural components of an SC-coil. The test results demonstrated that frictional heat had occurred at the boundary between an epoxy-impregnated superconducting coil and the coil fasteners. Furthermore, a method to reduce the frictional heat inside an SC-coil was considered by using a correlation between the hardness of the frictional surface and the amount of frictional heat. Then, an effect to reduce the frictional heat was demonstrated by means of a liquid-helium-cooled fretting test.

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Wrong:See PDF attached
Right:See PDF attached

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