Yoshinari Kanamori

Implementing time-interval class for managing temporal data

This paper describes a way of implementing a conceptual model for temporal data on an object database system. In fact, the model which we have proposed is implemented as a class library. Any application can employ the library, because it does not depend on specific applications. Furthermore, we propose an enhanced version of Time Index. Temporal queries including a lot of events are effectively processed with the enhanced Time Index.

An Air Index for Data Access over Multiple Wireless Broadcast Channels

In this paper, we propose an index allocation method for data access over multiple wireless channels. Our method first derives external index information from the scheduled data, and then allocates it over upper channels. Moreover, local exponential indexes with different parameters are built within each channel for local data search. Experiments are performed to compare the effectiveness of our approach with an existing approach. The results show that our method outperforms the existing method.

Versioning model of image objects for easy development of image database applications

A versioning model is presented for managing and controlling image objects in an image database. Image objects consist of attributes such as pixel data and methods such as image processing operations. Furthermore, image objects can be represented in terms of an application site model from the user viewpoint and an internal model from the implementation viewpoint. The former results in a virtual image object and the latter produces an actual object. When image processing is applied to an image object, a new image object is generated. The new object is understood to be a version of the original object, and a series of interactive operations generates a version history. Two concepts are introduced in order to manage version histories: a generic image object (GIO), a composite generic image object (CGIO). The kind of object generated depends on the image processing application. The features of versioning model are described and differences between version management of image objects and that of objects in CAD are discussed. An architecture that produces image objects and manages versions is proposed. The architecture is composed of three layers: an application layer, database layer, and an image object server. The server generates versions and controls their histories.

Interval-Based Representation of Spatio-Temporal Concepts

This paper proposes a method for representing numerous spatio-temporal concepts of objects appearing in image sequences. The objects are modeled approximately, by use of cuboids consisting of minimum bounding rectangles with time intervals. The spatial relations, including topological and directional relations and the distances between objects, are then defined. The definitions allow for uniform representations of the spatio-temporal queries on objects appearing in image sequences using intervals. This paper also gives examples of such queries for contents retrieval, and illustrates how they are performed in our method.

Retrieving tsunami digital library by use of mobile phones

We are developing a Tsunami Digital Library (TDL) which can store and manage documents about tsunami, tsunami run up simulations, newspaper articles, fieldwork data, etc. In this paper, we propose a public education against the tsunami disaster mitigation as one of TDL applications. For the education, we use mobile phones to retrieve TDL because we have to walk coast regions. Then, we have prepared summaries of documents and newspaper articles in TDL, and also developed query systems for mobile phone retrievals.

Several partitioning stratgegies for parallel image convolution in a network of heterogeneous workstations

Abstract Making use of many workstations connected by a network can give better performance than the same number of discrete workstations. We investigate various partitioning strategies for parallel digital image convolution in such a network. CORBA (Common Object Request Broker Architecture) is employed in implementing parallel processing with distributed workstations, allowing heterogeneous workstations to be used for parallel processing. We present a parallel and distributed image convolution processing model. We also describe several heterogeneous partitioning strategies and discuss the performance of each based on experimental results obtained by real implementation.

An Implementation Design of a Fine-Grained Database Access Control Policy Consistency Checking Mechanism

Policy consistency checker is an essential part of database access control systems. Realizing checking mechanisms for policy inconsistencies is a non-trivial task due to large amounts of rules and various kinds of rule patterns on fine-grained database objects and complicated interrelationships among those rules. We propose a novel rule-based mechanism for checking fine-grained access control policy inconsistencies for relational databases. In particular, we present necessary concepts and implementation design of the inconsistency checking mechanism. We specify policies, with conditions, on fine-grained objects through if-then authorization rules. We compute rule inconsistencies by employing the java-based open-source rule engine Jess.

Protecting personal data with various granularities: a logic-based access control approach

In this paper, we present a rule-based approach to fine-grained data-dependent access control for database systems. Authorization rules in this framework are described in a logical language that allows us to specify policies systematically and easily. The language expresses authorization rules based on the values, types, and semantics of data elements common to the relational data model. We demonstrate the applicability of our approach by describing several data-dependent policies using an example drawn from a medical information system.

Performance evaluation of combining data migration and method migration in object database environments

In this paper, we discuss efficient combinations of data migration processing and method migration processing in object database environments. When we have multiple servers and clients, it is practical to decide at a client which of the two ways should be adopted for performing each processing with a server for performance. This paper presents an analytical model of the two ways in object database environments. In addition, we report experimental results showing that the model enables us to get the efficient combination of them in most cases.

An approach to spatio-temporal queries

Contents retrieval from image sequences can be expressed with predicates on them. This paper introduces spatio-temporal predicates to be applied to image sequences. Numerous kinds of queries with spatio-temporal relations between objects, e.g., topological relations, direction relations, temporal relations, and combinations of them, are expressed with the predicates. We also show with examples how such queries are processed in a database storing interval data created by projecting objects appearing in image sequences on the x-, y-, or time-axis. A representation of spatio-temporal concepts is employed with primitive operations for illustrating the process in this paper.