Aki Kobayashi

Distributed supervisory system with cooperative multi-agent FEP

A large-scale distributed supervisory system that services a large area should ideally be capable of performing automatically optimal control based on various types of data provided by the controlled equipment. However, conventional systems have generally been configured so that pre-ordained transmission and reception processes are the input to the FEP (front end processor) unit according to various criteria of the data provided by the controlled equipment (e.g., the type and significance of the data, its priority, and its designated destination), while the host computer sends back a response to the controlled equipment based on the data transferred from the FEP according to preset optimal control algorithm. But to achieve fundamental improvements of system speed and reduce the load on the host computer, one must adopt the configuration in which the FEP can make automatic judgments regarding the criteria of data provided by a diverse variety of controlled equipment, instead of having to devise system-wide algorithms based on predetermined criteria in the data provided by the controlled equipment. To configure an FEP for this sort of system, we propose a method where a plurality of programs that identify the conditions of a specific type of data are prepared separately and integrated by means of a multi-agent architecture.

Cooperative multi-agent-based control technology for supervisory control and data-acquisition systems

Through the research reported here, a SCADA system with improved serviceability has been developed. Introducing the multi-agent (MA) technology into a distributed control system can reduce system and improved serviceability. To further improve serviceability and make the system more cost-effective, the predictive-agent function and inter-terminal parameter method were also applied. In addition, the systems distributed intelligent field terminals (IFTs) use a common algorithm that is unaffected by any changes to the system specifications. As a result of these innovations, the serviceability of the proposed system is significantly improved compared to that of conventional systems. This system has been implemented for practical purposes at 29 sites.

Image information retrieval using rough set theory

We describe a method for automatically generating an image retrieval algorithm corresponding to keywords. The retrieval algorithm that we proposed consists of a scalar quantizer and discriminator and can be generated quickly and automatically by utilizing the idea of rough set theory. We demonstrated through experiments that the proposed method is effective to generate image retrieval algorithms.

QoS multicast protocol for live streaming

Live streaming media are delay sensitive and have limited allowable delays. Current conventional multicast protocols do not have a loss retransmission mechanism. Even though several reliable multicast protocols with retransmission mechanisms have been proposed, the long delay and high packet loss rate make them inefficient for live streaming. This paper proposes a multicast protocol focusing on the allowable delay called the QoS Multicast for Live Streaming (QMLS) protocol. QMLS routers are placed along the multicast tree to detect and retransmit lost packets. We propose a method that enables data recovery to be done immediately after lost packets are detected by the QMLS router and a method that reduces the unnecessary packets sent to end receivers. This paper discusses the mathematical analysis of the proposed protocol and compares it with other multicast protocols. The results reveal that our protocol is more effective in live streaming. Finally, we do a simulation to evaluate its performance and study the effect of consecutive losses. The simulation reveals that consecutive losses can slightly increase losses with our protocol.

Image retrieval by estimating parameters of distance measure

This paper describes an image retrieval system that searches a database for images similar to a target imagined by a user. The system uses image features, rather than keywords, and retrieves images by estimating distance parameters. We use the Mahalanobis distance as the distance measure. The system, first, presents the user some images with a suitable feature vector value and asks the user to select images that are similar to the target he has in mind. Based on the users selection, the system revises the distance parameters. This process is continued until the target region is reduced to a suitable volume. Since this method requires neither a real target image nor keywords to do the retrieval, it is quite simple and practical. Experimental results show the advantage and efficiency of the proposed system.

Image retrieval system based on interactive reduction of feature space

This paper proposes an image retrieval system, which searches a database for images similar to a target imagined by a user. The system uses image features, rather than keywords, and retrieves images by reducing a multidimensional feature space generated by the image feature vectors. The system presents the user sample images, with a suitable feature vector value, and requires the users interaction to obtain information regarding application of specific images. The information is then used to appropriately reduce the feature space. This process continues, until the target region is reduced to a suitable volume. Since this method requires neither a real target image nor keywords in retrieving, it is quite simple and practical. Experimental results show the advantage and efficiency of the proposed system.

A Proposal for a Multicast Protocol for Live Media

Live streaming media is delay sensitive with small allowable delay. Current conventional multicast protocols do not provide a loss retransmission mechanism. Even there are some researches on a reliable multicast providing a loss retransmission mechanism but a long delay and a high packet loss rate make them inefficient for live streaming. This paper proposes a new multicast protocol based on a protocol relay concept. The proposed protocol focusing on allowable delay provides Quality of Service (QoS) for live streaming. Relay nodes are placed along the multicast tree. Data recovery is done between relay nodes. We propose the methods that enable protocol relays to request retransmission immediately and reduce the number of duplicate packets. Finally, we make a mathematical analysis of the proposed protocol and compare it with other multicast protocols. The results show that the proposed protocol is more efficient for live streaming than the conventional protocols.

Dynamic activating and deactivating loss recovery router for live streaming multicast

Live streaming is delay sensitive and can tolerate some amount of loss. The QoS Multicast for Live Streaming (QMLS) Protocol, focuses on the characteristics of live streaming. It has been shown to improve the performance of live streaming multicast by reducing the end-to-end packet loss probability. However, the placement of active routers performing the QMLS function has not been discussed. This paper proposes a dynamic method to activate and deactivate routers in order to minimize the number of active routers for each QMLS-packet flow and discusses its parameters. The results of an evaluation show that the proposed method can reduce the number of active routers for each flow and adjust the active routers according to changes in the multicast tree.

Network information retrieval method controlled by energy and division probability parameters

Conventional retrieval methods tend to either satisfy network administrators by reducing network traffic as flooding method, or to satisfy network users by increasing the speed of a successful search as sequential retrieval method, and these are conflicting demands. However, these retrieval methods do not consider the existence probability of target objects on a network. In this paper, we propose a new retrieval method that is flexibly adapted to the existence probability of target objects and to specified requirements of discovery probability, search time, and traffic level. This proposed method is a single query action based on an autonomous distributed network that freely changes the weight between network traffic and discovery probability according to retrieval requirements. The simulation results reveal that network traffic can be decreased by setting appropriate values for the energy and division probability of query messages with little reduction in the discovery probability of the retrieval target object.

Link Information Consistency Methods Using Update Notification on theWeb

The Cooperative Web Architecture (CWA) was proposed for relevant information retrieval using Web-Graph. In CWA, the Web servers maintain and deliver the neighboring link information (Web-Subgraph). When events that change the Web-Graph occur, the Web servers notify each other of the change in order to synchronize Web-Subgraphs. In this paper, we propose a synchronization method to solve a problem of inconsistency among Web-Subgraphs. This problem occurs because of the time difference between notifications. When multiple events occur simultaneously, the range of notification becomes invalid. Therefore the inconsistency problem occurs. We proposed two types of synchronization methods, then we compare and analyze their respective characteristics. Moreover we discuss feasibility from the viewpoint of traffic.