Masayuki Matsumoto

DENSITY DEPENDENCE OF ROTATIONAL RELAXATION OF SUPERCRITICAL CF3H

Polarized and depolarized Raman scattering measurement and molecular dynamics (MD) calculations have been performed for supercritical CF3H at various densities along an isotherm higher than Tc by about 6 K in order to investigate the density dependence of rotational relaxation. The rotational autocorrelation functions obtained from both methods, which are in satisfactory agreement with each other, showed liquid‐like diffusional decay for the fluid at densities higher than ρc. The function changed in shape continuously to a nearly free‐rotor‐like one at the lowest density going through the oscillatory ones at intermediate densities. The detailed analysis based upon the MD trajectories has been done in order to clarify the relaxation mechanism at each density. Applicability of the J‐extended diffusion model was also examined. They showed that the density dependence of the rotational relaxation may be explained in terms of the states of molecular aggregation in the fluid.

Novel Railway Signal Control System Based on the Internet Technology and Its Distributed Control Architecture

We have developed a novel railway signal control system that operates as a distributed system. It consists of a central control unit (called LC) and terminal devices (called FC) that are distributed at the railroad wayside aid operate signal devices. The Internet technologies and optical LAN technologies have been used as communication methods between the LC and the FCs. While handling enormous amount of electric cables may cause human errors, the system is expected to reduce troubles of the current signal system at construction works thanks to the Internet technologies. The FC is a distributed terminal device that has its own processor and placed at the railroad wayside to control the field signal devices. The LC is a centralized computer device that has software arranged by the function of the field devices. An optical network system and multiple communication paths between the LC and the FCs realize durable transmissions. Moreover, the assure performance of controls and transmissions have been investigated, and the autonomous distributed signal control system is also discussed as the next steps of the system

The new ATC system with an autonomous speed control with on-board equipment

The paper introduces a new digital ATC (automatic train control device) system developed by East Japan Railway Company (JR East). In the current ATC, the central ATC logic device calculates permissive speed of each blocking section and controls speed of all trains. On the other hand, in the new digital ATC, the central logic device calculates each position to which a train can move safely, and sends the information on positions to all trains. On each train, the on-board equipment calculates an appropriate braking pattern with the information, and controls velocity of the train. That is, in the new system, the device on each train autonomously calculates permissive speed of each train. These special features realize ideal speed control of each train, making full use of its performance for acceleration and deceleration, which in turns allows high-density train operations.

A Novel Railway Signal Control System Based on the Internet Technology and an Assurance Technology

We have developed a novel railway signal control system that works as a distributed system. It consists of a central control unit (called LC) and terminal devices (called FC) that are distributed at the railroad wayside and operate signal devices. The Internet technologies and optical LAN technologies have been used as communication methods between the LC and the FCs. The FC is a distributed terminal device that has its own processor and placed at the railroad wayside to control the field signal devices. The LC is a centralized computer device that has software arranged by the function of the field devices. An optical network system and multiple communication paths between the LC and the FCs realize robust transmissions. Moreover, the assure performance of controls and transmissions have been investigated, and the autonomous distributed signal control system is also discussed as the next steps of the system.

High assurance technologies for autonomous decentralized train control system

The securing of transportation capacity, high degrees of safely and high reliability are required for train control systems in high-density train operation sections. We have proposed the autonomous decentralized train control system as a system that meets these requirements and construction of the system is currently proceeding. However the replacement to the new system while operating the current ATC system must not influence the operations of the system. In addition, it is also necessary to configure the system so that technology that allows the current and new systems to coexist, system starting, countermeasures in emergencies and such do not influence the overall system. The technology that supports these is assurance technology. This technology has also been used in the train control system for the Yamanote and Keihin Tohoku Lines.

Assurance technologies for autonomous train on-board computer system

Railway companies operating in major cities or between major cities must conduct high-density transportation and safely transport as many passengers as possible. Securing transportation capacity and high degrees of safety and reliability are required for train control systems in high-density train operation sections. Of the many lines operated by JR East, the Shinkansen and Tokyo Metropolitan Area line sections are sections with very strong needs concerning high-density, safe, and stable transportation. We have proposed an autonomous decentralized train control system as a system that meets these requirements and construction of this new system is currently proceeding. However, replacement by the new system while operating the current ATC system must not influence daily operations of the latter. In addition, it is also necessary to configure the new system so that technology that allows the current and new systems to coexist, including system starting and countermeasures in emergencies, etc. does not influence the overall system. The technology that supports this is assurance technologies. This technology has also been used in the train control system for the Yamanote and Keihin Tohoku Lines.

A Railway Signal Control System by Optical LAN and Design Simplification

When replace railway interlocking devices, setting up of large number of signal cables and confirming of wiring connections are required. So, it is worried that serious transport disorder caused by human error in wiring works would occur. We have developed a railway signal control system utilized optical LAN to reduce the signal cables and wiring works. Moreover, all signal devices operate independently, designers have to handle all devices one by one and pay great attention to avoid causing harmful influence each other. We propose the data-driven method to make easy to replace interlocking device. This logic is rearranged according to the field device in order to simplify and decrease design duties of designers. In this paper, we introduce this system, and describe network transmission, safety-related communication and software configuration of the system.

Integration of automatic train control system

In current automatic train control system, the central ATC logic device produces position of each train and calculates permissible speed of each blocking section. Therefore the central logic device controls speed of all trains. On the other hand, in the new system proposed by this paper, there is no logical central device and train can run completely autonomously. In the changing period of current ATC to the new system, we integrate these two heterogeneous systems. For getting the assurance high, the test is very important. Comparing with the conventional method, this paper proposes a high assurance method.

Application of Assurance Technology for Railway Signaling System

The railway signaling system has recently achieved realization of new functions by using assurance technology. By constructing systems in stages, making both control data and information data coexist on the same network, and realizing coexistence of both old and new systems, we succeeded in introducing a large-scale system as well as system change. This method also improved services to customers such as a decrease in train delay and continuation of train operation. Assurance technology can now be applied not only to systems in which we have already used this technology in systemization, but also to many other railway systems. On the other hand, when we try to change a complex and large-scale system, it is difficult to do so in order to accommodate new needs with completely new functions, since the new system will be affected by the existing system. We reviewed ways to solve this problem by using assurance technology

Dependable automatic train control system using digital track signals

An architecture for an ATC (automatic train control) system using digital track circuit signals is presented. Its key ideas are the following. (1) Digital track signals expand flexibility of the ATC system design without compromising safety. In comparison with the present analog type ATC typically in use, the probability of the new system being down is expected to drop below one third, and the space occupied by equipment for the new system is halved. (2) Jointless track circuits realize an overlay track circuit compatible with current track circuits. (3) The unity control zone, consisting of a few stations, can function whether a neighboring zone exists or not. (4) The multifunction ATC device on board can process present and new ATC signals simultaneously. (5) Items (2), (3) and (4) allow step-by-step system construction.