Akira Kawaguchi

• Doctor of Philosophy
• City College of New York

Overlay networks are logical networks embedded in physical substrate networks. They are useful for supporting specialized applications involving computation and information exchange among subsets of users. This paper examines the characteristics of overlays that make them suitable for different applications in dynamic, distributed database environm...

This paper will demonstrate a novel method for consolidating data in an engineered hypercube network for the purpose of optimizing query processing. Query processing typically calls for merging data collected from a small subset of server nodes in a network. This poses the problem of managing efficiently the exchange of data between processing node...

We previously proposed a method to locate high packet-delay variance links for OpenFlow networks by probing multicast measurement packets along a designed route and by collecting flow-stats of the probe packets from selected OpenFlow switches (OFSs). It is worth noting that the packet-delay variance of a link is estimated based on arrival time inte...

Systems for Internet of Things (IoT) have generated new requirements in all aspects of their development and deployment, including expanded Quality of Service (QoS) needs, enhanced resiliency of computing and connectivity, and the scalability to support massive numbers of end devices in a variety of applications. The research reported here concerns...

Background The development and use of mobile health (mHealth) apps for asthma management have risen dramatically over the past two decades. Asthma apps vary widely in their content and features; however, prior research has rarely examined preferences of users of publicly available apps. Objective The goals of this study were to provide a descripti...

BACKGROUND The development and use of mobile health (mHealth) apps for asthma management have risen dramatically over the past two decades. Asthma apps vary widely in their content and features; however, prior research has rarely examined preferences of users of publicly available apps. OBJECTIVE The goals of this study were to provide a descripti...

This paper addresses the general problem of reducing unnecessary message transmission thereby lowering overall bandwidth utilization in a Peer-to-Peer (P2P) network. In particular, we exploit the characteristics of a P2P network engineered to resemble a hypercube. The reason for doing this is to achieve constant computation time for inter-node dist...

A Dynamic Distributed Federated Database (DDFD) offers advantages in a variety of applications. In previous work we introduced HyperD, a DDFD whose nodes are arranged in a virtual hypercube structure. We showed that this engineered structure reduces the cost of communication and facilitates processing of complex queries involving joins and semijoin...

We examine the problem of distributed join query op-timization in a Dynamic Distributed Federated Database (DDFD) and the role that network topology, specifically an engineered hypercube, could play in the cost estimation. Considering that many nodes in a DDFD may rely on batteries and wireless radios, we should like to minimize network information...

Classical work on query optimization has not taken account of the topology of distributed database networks as a cost factor in executing standard operations in relational algebra. Here we propose to remedy this deficiency by comparing the cost of query optimization in a known topology (such as the hypercube) to the cost of performing the same oper...

While microarray experiments generate voluminous data, discerning trends that support an existing or alternative paradigm is challenging. To synergize hypothesis building and testing, we designed the Pathogen Associated Drosophila MicroArray (PADMA) database for easy retrieval and comparison of microarray results from immunity-related experiments (...

This paper presents a new approach for analyzing several important properties of marine traffic in which a number of ships pass through a restricted route. A key concept introduced is a mapping made from those spatially distributed ships into a Voronoi tessellation. A region interior of each Voronoi cell becomes equivalent to a dominance region of...

Classical work on query optimization has not taken account of the topology of distributed database networks as a cost factor in executing standard operations in relational algebra. Here we propose to remedy this deficiency by comparing the cost of query optimization in a known topology (such as the hypercube) to the cost of performing the same oper...

The New York State Department of Transportation (NYSDOT) maintains an inventory of over 17,000 highway bridges across the state. These bridges are inspected biennially or more often as necessary. Bridge inspectors are required to assign a condition rating for up to 47 structural elements of each bridge, including 25 components of each span of a bri...

This paper discusses the implementation of one type of information system for the New York City bus transit service, as a case study to provide value-added transportation services for people with impaired mobility. Information technology is a key tool for finding flexible transportation services, especially for disabled people. Useful information s...

The subject of this chapter is a high-level discussion to address the problem of our society in the coming age. The mechatronics approach outlined here is the framework and methodology to cope with the influx of vulnerable people in mobile wheelchairs. The concept of the micro and macro-control architecture based on the proposed mechatronics approa...

Computerised navigation is a developing technology in a branch of autonomous and intelligent engineering systems. It aims to enhance safety and security at sea and to improve the reliability of ship-to-ship operations and global marine traffic control. A recently standardised automatic identification system (AIS) takes full advantage of GPS based r...

This research aims at utilizing the marine traffic flow simulation based on an autonomous ship cluster behavior model for route planning. Marine traffic flow simulations were performed with various route dimensions and traffic conditions, and the route navigation characteristics of ship agents were investigated. The marine traffic flow simulation s...

We present the development of new database, called PADMA, for easy retrieval of genes whose expression is altered by parasitoid infections. The database also houses gene expression data sets from Drosophila blood cells after immune activation. The PADMA system will allow a user to compare genes whose expression is altered after infection by a singl...

This paper explores a pragmatic establishment of healthcare techniques dedicated to improving the safety and drivability of electric power wheelchairs. The focus of the study is an analysis of the relationship between passenger’s posture behavior and comfort sensation in riding mobile wheelchair. We propose a new driving control system, by construc...

This paper discusses the implementation of one type of information systems for the New York City bus transit service, as a case study to provide value-added transportation services for the people in need of mobile wheelchairs. Information technology is a key for finding out flexible transportation services especially for disabled people. Useful inf...

Management of infrastructure assets has been gaining increased attention recently because of aging infrastructures. Wastewater infrastructures, such as sewers, force mains, etc., maintained by various municipalities across the nation are at increased risk of failure since they are buried underground and are usually scheduled for maintenance/repair...

Management of infrastructure assets has been gaining increased attention recently because of aging infrastructures. Wastewater infrastructures, such as sewers, force mains, etc., maintained by various municipalities across the nation are at increased risk of failure since they are buried underground and are usually scheduled for maintenance/repair...

Linear programming is a powerful optimization technique and an important field in the areas of science, engineering, and business. Large-scale linear programming problems arise in many practical applications, and solving these problems requires an integration of data- analysis and data-manipulation capabilities. Database technology has become a cen...

This paper describes an improvement made for the expressive capabilities of the ship cluster behavior model. The goal of this study is to realize a pseudo realistic marine traffic flow analysis in the complex sea environment. The approach is based on the development of the proactive means capable of detecting obstacles and assisting safe group navi...

The cost of computation becomes a bottleneck for an agent based marine traffic simulation. This is especially true when investigating interferences of a large number of ships and static objects placed in the sea. In general, a collection of ship agents built with a simple sensing model mandates a quadratic time complexity of O (n^2) for sensing eac...

This research aims for an establishment of a global center that will advance the knowledge in real-time human and goods transport. The focus of this paper is an approach for addressing the performance and feasibility issues with respect to a reliable and distributed traffic data communication network for optimal and secure routing of traffic. We pr...

This paper presents a simulation study of the characteristics of the northbound and southbound traffic in Tokyo Bay using various ship agents, and discusses these agents' capability of recapturing the marine traffic flow. Each ship agent consists of a sensor, a decision-making function, memory, and an effector. The decision-making function performs...

Solving large-scale optimization problems requires an integration of data-analysis and data-manipulation capabilities. Nevertheless, little attempt has been made to facilitate general linear programming solvers for database environments. Dozens of sophisticated tools and software libraries that implement linear programming model can be found. But,...

Management of infrastructure assets has been gaining increased attention recently because of aging infrastructures. Wastewater infrastructures, such as sewers, force mains, etc., maintained by various municipalities across the nation are at increased risk of failure since they are buried underground and are usually scheduled for maintenance/repair...

New York State Department of Transportation maintains an inventory of over 20,000 bridges across the state. These bridges are inspected biannually based on rating criteria of 1 to 7, 7 being new and 1 being failed. Bridge inspection ratings can be used to calculate deterioration rates of bridge elements by considering effects of environmental (clim...

This paper presents a simulation study of the characteristics of the northbound traffic in Tokyo Bay using ship agents. A ship agent has four functions, i.e., sensor, decision-making, memory and effecter functions. The decision-making function performs circumstantial judgments and makes course and speed adjustments utilizing a ship cluster behavior...

Previous research on materialized views has primarily been in the context of flat relational databases—materialized views defined in terms of one or more flat relations. This paper discusses a broader class of view definitions-materialized views defined over a nested data model such as the nested relational model or an object-oriented data model. A...

This paper presents a simulation study of ship cluster merging and separation characteristics using a ship cluster behavior model. In order to simulate merging and separation of ship clusters, it is necessary to establish a cluster membership recognition rule. Four kinds of such rules (course-dependent, distance-dependent, inclusive and exclusive r...

This paper presents a simulation study of the characteristics of obstacle avoidance and passage navigation by multiple ships forming a group. To make this possible, we added two new forces, i.e. obstacles avoidance force and scrape avoidance force to the previous model that only had four independent forces, i.e., goal attainment, contracting, expan...

This paper examines a real-time measure of bias in Web search engines. The measure captures the degree to which the distribution of URLs, retrieved in response to a query, deviates from an ideal or fair distribution for that query. This ideal is approximated by the distribution produced by a collection of search engines. Differences between bias an...

The aim of this research is to realize a computerized, intelligent, and autonomous system to support navigation for multiple ocean-going vessels that share the same sail-ing course like a transport convoy. Detecting and evad-ing other clusters in close proximity is one of the most important tasks in navigation as contacting these will po-tentially...

This paper presents a study of the relationship between the emergence characteristics of a ship cluster and the size of information search space using an autonomous ship behavior cluster model. First, we tested four different decision-making functions, and chose one function that led to highest stability in terms of the ship cluster configuration....

Wireless technology is an extension and adaptation of existing applications on laptop computers. This research aims to build a prototype system that supports the transference of existing Web-based database applications into the wireless handheld environment. The system uses a meta specification approach to eliminate programming work. The user need...

As mobile computing is becoming the dominant computing paradigm, the increasing ease with which PDAs can gain wireless access to the Web offers new opportunities and challenges to Web application designers. The application of this fast-developing technology in the healthcare industry will bring promising economic and technology contributions. Howev...

This paper presents an analysis of ship-group navigation simulations based on an autonomous ship behavior cluster model. In this model, maneuvering decisions of a ship agent are computed by combining four independent forces : goal attainment force, contracting force, expanding force, and cluster collision avoidance force. The magnitude of each forc...

This paper presents a study and analysis of marine traffic in which multiple clusters of ships meet in the waterway. Our earlier work of an autonomous ship cluster behavior model is used, with an improvement, to realize the simulation environment. A vessel's maneuvering decision is computed by combining four independent forces : goal attainment for...

This paper deals with a marine traffic simulation based on an autonomous ship cluster behavior model in which each vessel's maneuvering decision is made by taking into consideration four independent forces that act on it, namely, goal attainment, centripetal, collision avoidance, and following forces. The compositional force, which determines each...

This paper is a progress report on an ongoing research effort that makes use of wireless biometric data management, specifically a wireless blood-glucose monitoring system (WBgM). The goal of this research is to realize appropriate timely intervention by health-care providers in response to records of unregulated blood-glucose level in order to mai...

Subway tunnel condition assessment presents significant challenges for engineers and managers and is becoming increasingly important as the systems continue to age. Tunnels are in constant heavy use in an aggressive environment. Tunnel systems are vast, dark, and noisy. The national investment in subway tunnels is enormous, and careful maintenance...

Discusses the issue of search bias on the Internet. Measure of bias; Countering ill effects of search engine bias by making a number of alternative engines available.

This paper deals with the measurement of bias in search engines on the World Wide Web. Bias is taken to mean the balance and representativeness of items in a collection retrieved from a database for a set of queries. This calls for assessing the degree to which the distribution of items in a collection deviates from the ideal. Ascertaining this ide...

This paper evaluates and compares the performance of two-phase locking divergence control (2PLDC) and optimistic divergence control (ODC) algorithms using a comprehensive centralized database simulation model. We examine a system with multiclass workloads in which on-line update transactions and long-duration queries progress based on epsilon seria...

Materialized views and view maintenance are becoming increasingly important in practice. In order to satisfy different data currency and performance requirements, a number of view maintenance policies have been proposed. Immediate maintenance involves a potential refresh of the view after every update to the deriving tables. When staleness of views...

We consider concurrency control problems that arise in the presence of materialized views. Consider a database system supporting materialized views to speed up queries. For a range of important applications (e.g. banking, billing, network management), transactions that access materialized views would like to get some consistency guarantees—if a tra...

The authors consider parallel processing of a graph represented by a database relation. They propose a methodology for analyzing the speedup of a parallel processing strategy with the purpose of selecting at run-time one of several candidate strategies, depending on the hardware architecture and the input graph. They study the single-source reachab...

In this paper we consider parallel processing of a graph represented by a database relation, and we achieved two objectives. First, we propose a methodology for analyzing the speedup of a parallel processing strategy with the purpose of selecting at runtime one of several candidate strategies, depending on the hardware architecture and the input gr...

Thesis (Ph. D.)--Columbia University, 1998. Includes bibliographical references. Department: Computer Science.