Shinsuke Tamura

Performance validation of a functionally distributed energy management architecture

The authors propose a functionally distributed computer (FDS) system for an energy management system (EMS) and a large-scale supervisory control and data acquisition (SCADA) system. The FDS consists of small-scale functional units executing simple functions and is characterized by both parallel processing and independence of subsystems. These units are mostly composed of microcomputers. The feasibility of such a system was investigated and results are reported. Such a system would improve performance, increase the flexibility of expansion, improve reliability, and reduce costs. >

HMS Development and Implementation Environments

In this chapter, desirable features of Holonic Manufacturing System (HMS) development and implementation environments are extracted, and HMS-Shell and JDPS are explained, as examples that provide these features. HMS-Shell is a GUI-based design tool for HMSs based on the Cooperation Domain (CD) that encapsulates cooperation partners and cooperation protocols. JDPS is a HMS implementation and execution environment based on reliable broadcast messaging that achieves complete location and multiplication transparency of entities. These features of HMS-Shell and JDPS make application programs independent of cooperation mechanisms, and enable easy dynamic reconfiguration and incremental development of HMSs while systems are in operation.

A new path planning algorithm for manipulators

This paper proposes a path-planning algorithm for multi-arm manipulators that calculates paths by searching grid points in Euclidean space directly instead of configuration space. The algorithm is back track free and resolution complete. Different from existing resolution complete algorithms, its computation time and memory space are proportional to the number of arms. Therefore paths can be calculated within practical time even for manipulators with many arms, and it becomes possible to apply it to manipulators that operate in complicated and fully automated environments. Effectiveness of the algorithm is evaluated by applying a preliminary prototype to path-planning in 2-dimensional space.

Development of Intellectual Distributed Processing System

Abstract The Intellectual Distributed Processing System (IDPS) does not have any centralized managing element. IDPS system elements find their roles autonomously, in order to complete given objectives. IDPS system elements are also able to solve conflicts among different objectives without any supervisory element, by exchanging information among elements. In this paper, fundamental mechanisms for managing system elements distributedly are described. These mechanisms are implemented on the object oriented distributed operating system, which has been developed on multi micro computers connected by local area network. It is expected that large scale adaptive systems can be developed and operated easier by these mechanisms.

Power system voltage control by distributed expert systems

Voltage control by distributed expert systems has been investigated as a case study of the application of a distributed control scheme to power system control. The combined injection of VAr-compensating devices controlled by distributed expert systems has been proposed as a measure to maintain voltage stability in heavy loading conditions of a power system. A simulation study has been carried out using five workstations which represent a power system and four VAr-compensating devices. The results demonstrate the effectiveness of the proposed system for voltage recovery.<<ETX>>

Development of Anonymous Networks Based on Symmetric Key Encryptions

Anonymous networks enable entities to send messages without disclosing their identities. Many anonymous networks had been proposed already, such as Mixnet, DC-net, Crowds, etc., however, they still have serious drawbacks. Namely, they require tremendous computation overheads to transmit messages over networks. That is because asymmetric key encryption algorithms are used. This paper proposes ESEBM (Enhanced Symmetric Key Encryption based Mixnet), a new mechanism for anonymous communication that removes drawbacks of existing anonymous networks while exploiting symmetric key encryption algorithms. According to experimentations, throughput of ESEBM is about 1/4.4 of usual non-anonymous networks, and it achieves more than 36 times higher throughput compared with Mixnet. In addition, different from existing anonymous networks, ESEBM can handle reply messages without any additional mechanism, and it can protect itself from various threats, e.g. DOS attacks and message forgeries.

A fault-tolerant architecture based on autonomous replicated objects

The paper proposes an architecture for the replication of program modules enabling them to behave in accordance with their own local knowledge, without any influence by not only their location, replication degree and fault-tolerant mechanism but also system level modules. In the proposed architecture, program modules are implemented as objects and communication among them is carried out by a total ordering broadcast protocol, enabling individual objects to behave autonomously. Therefore, individual objects can choose the most suitable replication degree and fault-tolerant mechanism in accordance with their own required reliability and execution efficiency without the need to change programs or for the object location to be influenced.<<ETX>>

A Fault-Tolerant Architecture for the Intellectual Distributed Processing System

The Intellectual Distributed Processing System (IDPS) is a system architecture to realize highly extensible and adaptive distributed systems. The reliability of the IDPS relies on replicated objects model, and this paper presents two new mechanisms for implementing that model on the IDPS. One is a fail-stop broadcast communication protocol, where replicated objects receive the same messages in the same order. The other is a commitment method, where each object receives only correct messages. By these mechanisms, an individual object does not need to be aware of the replication degree and the location of relevant objects. Moreover, each object can communicate with other individual objects without confirming message transmission. Therefore, the overhead for the fault-tolerant mechanisms can be maintained at a small level.

Intellectual Distributed Processing System Development

The Intellectual Distributed Processing System (IDPS) is a system which has no centralized managing element. IDPS system elements find their roles autonomously in order to complete objectives given to the system. IDPS system elements are also able to solve conflicts among different objectives without any supervisory element, by exchanging information among elements.

Distributed Deadlock Avoidance and Detection in Intellectual Distributed Processing System

Distributed systems have advantages in developing large, flexible, and reliable systems. The Intellectual Distributed Processing System(IDPS) eliminates all central managing mechanisms from systems in order to make the best use of these advantages. This paper describes the deadlock avoidance and detection method adopted in the IDPS. The proposed mechanism has the following characteristics. 1) The proposed mechanism, which is completely distributed, is carried out by communication among jobs and resources. Therefore, it is possible to make highly flexible and reliable systems easily, Moreover, the proposed mechanism does not trace individual hold-claim and/or hold-wait relations in directed graphs sequentially. Therefore, it is possible to execute deadlock handlings in parallel on different sites. 2) It is possible to use deadlock avoidance and detection mechanisms simultaneously. Deadlock detection is used for data resources and deadlock avoidance is used for physical resources.