Kazunori Fujiwara

Widely-distributed train-traffic computer control system and its step-by-step construction

In a large scale mission critical real time control system, such as the Tokyo metropolitan area train traffic system, it is very difficult to construct the entire system at once. Moreover economic considerations makes year by year investment inevitable for developing the system. The new Tokyo metropolitan area train traffic computer control system, supplying service to 19 train lines, 300 stations and 6200 trains per day, has been constructed step by step over 8 years without halting train operations. Here the computer system is required to be expandable online during system operation and without disrupting already constructed subsystems. To enable testing during system operation, an autonomous decentralized online expansion technique is proposed. Then the effectiveness of the technique is demonstrated in a real system.<<ETX>>

On-line testing for application software of widely distributed system

Widely distributed systems are constructed step-by-step over a long lime. These systems must permit on-line testing. On-line testing verifies newly added application software by receiving the real data in the real environment without disrupting the operating subsystems. To enable testing during system operation, an on-line test technique based on autonomous decentralized system structure was proposed. In this paper, the functions to verify various types of application software are proposed: (1) for non-real-time application software, checking whether it communicates with every operating application software. (2) for real-time application software, checking whether timing of output data is within the timing-deadline or not. (3) for new version software, verifying whether the version of all functions is newer than that off functions in the present software. An example of application software applied to the on-line test and the effectiveness of the technique is shown in a real system.

A high-speed labeling algorithm for raster-scanned type

Labeling is a procedure by which labels are assigned separately to a number of connected components, and it is also one of the important functions in the image processing system. In the conventional raster-scanned labeling, labels are assigned temporarily in a small local area. Then a large number of temporary labels (pairs of connected labels) is generated for the same connected component, and a long processing time is required to unify and transform them into the final label. From such a viewpoint, this paper discusses the reduction of processing time for the unification of pairs of connected labels. As a result, it is concluded that the following two approaches are effective: 1 Simplify the table structure for storing the pairs of connected labels 2 Reduce the generation of the pairs of connected labels. The following MIN-MAX method is devised as a means to realize (1). In the table storing the pairs of connected labels, MAX of the two temporary labels forming the pair of connected labels is adopted as the address, and MIN is used as the content data. To realize (2), it is noted that the concave and indented connected components often produce the pair of connected labels. The pixel-embedding and the forward pixel referring methods are devised for such situations. This paper presents the algorithms for those methods, and reports on the result of evaluation.

Assurance technology for Tokyo Metropolitan Railway Network

System needs of growing systems including heterogeneous functions and operations are increased. High assurance system that achieves high reliability and high availability is very important for such systems. In order to realize high assurance system, we developed the assurance technology based on ADS (Autonomous Decentralized System). When a growing system changes or grows, its reliability may be lowered. In this paper, we clarify the risk factors which lower the reliability and quality of a growing system when the system is modified. We will then examine the technology to eliminate or mitigate those risk factors, and propose adaptive assurance technology that can minimize the risk. We also applied this technology to ATOS (Autonomous Decentralized Transport Operation Control System) for Tokyo Metropolitan Railway Network as an example of really changing and growing system and mention its effectiveness.