Hiroyuki Inaba

Adaptive computer-based spatial-filtering method for more accurate estimation of the surface velocity of debris flow

An adaptive computer-based spatial-filtering velocimeter to measure the surface velocity of a natural debris flow with high accuracy is described that can adjust the filter parameters, specifically, the slit width of the filter, based on the surface-pattern characteristics of the flow. A computer simulation confirms the effectiveness of this technique. The surface velocity of a natural debris flow at the Mt. Yakedake Volcano, Japan, was estimated by this adaptive method, and the results were compared with those obtained by two other methods: hardware-based spatial filtering and normal computer-based spatial filtering.

Estimation of the surface velocity of debris flow with computer-based spatial filtering

A computer-based spatial-filtering velocimeter to measure the surface velocity of natural debris flow is described. This is a simple and interesting technique implemented with a spatial filter constructed as a software program that processes the video image of debris flow instead of a hardware implementation. The surface velocity of the debris flow at the Mt. Yakedake Volcano, Japan, was estimated by this computer-based spatial-filtering method, and the results were compared with those obtained by a hardware-based spatial-filtering method. Computer-based spatial filtering has the important advantage of a capability for tuning the spatial-filter parameters to the target flow.

Large motion estimation by gradient technique - application to debris flow velocity field

Abstract The gradient-based methods that are commonly used for the estimation of two-dimensional velocity field or optical flow behave poorly in the estimation of large motion. A preprocessing multiscale smoothing operation is proposed in the present paper to overcome this problem. Its effectiveness is confirmed by application to synthetic moving images and finally to the velocity field estimation of a natural debris flow along with a gradient-based method known as spatio temporal derivative space method.

Proposal of new authentication method in Wi-Fi access using Bitcoin 2.0

Recently, Wi-Fi hotspots are installed at several places. However most communications are not encrypted and the illegal can use it maliciously, therefore effective breakthrough are required. We propose a solution of these problems using a new method derived from Bitcoin. This method uses Blockchain and logs of user access are saved to it. The administrators can identify illegal person and collect users statistics. Bitcoin address can be used as encryption keys for communications. The Blockchain also provides a platform of regional applications. Furthermore, systems can cooperate with others at different places.

Surface Velocity Computation of Debris Flows by Vector Field Measurements

Abstract The surface velocity of natural debris flows is one of the main physical parameters for developing effective disaster prevention techniques. The authors already presented the result of velocity vector field measurement of debris flow by the spatio temporal derivative space method. In this paper, we propose a multi resolution spatio temporal derivative space method, and apply the method to some real debris flow video images.

Debris flow velocity estimation: a comparison between gradient-based method and cross-correlation method

Debris flow causes lot of damages all over the world. The surface velocity of such a natural random flow is one of the important physical parameters that are considered in drawing a hazard map or constructing a sediment control dam. Gradient-based method along with a multiscale smoothing operation finds application in the two-dimensional velocity estimation of a debris flow from its video images. This paper investigates the performance of another optical flow determination technique - the cross-correlation method in the above application and compares the results with those obtained by the gradient-based method. A computer simulation with synthetic random moving images shows that the accuracy of the cross correlation method is higher than that of the gradient-based method.

Notes on codes for synchronization error correcting

The synchronization problem is one of the most important technical issues in digital communication or storage systems. Conventionally, a synchronization pattern is inserted between frames. In this paper, we show that a class of binary expanded Reed-Solomon code is self-synchronizable. The Reed-Solomon code defined over GF(2/sup m/) has an ability of correcting synchronisation error of less than or equal to /spl plusmn/m/2 bits. Furthermore we propose a decoding algorithm of the Reed-Solomon code for synchronization error.

An IDS Visualization System for Anomalous Warning Events

Recently, illegal access to the network is increasing. It has been a serious problem. To deal with this problem, necessity of Intrusion Detection System(IDS) is increasing. IDS is the notifying system of network manager to inspect symptoms of the illegal access. IDS enables us to early detect threatening attack to the computers and to deal with its attacks. However there is a problem of IDS. It is tremendous warning logs especially for large scale network. Analyzing these logs apply a large amount of load to a network manager. To overcome this problem, there exist several methods for analyzing logs based on past tendency and some visualization methods for the logs. In this paper, we propose a novel visualization system of IDS considering order relation of IP addresses that emphasize the anomalous warning events based on past tendency.