Hiroshi Inujima

Bridge diagnosis system by using wireless sensor network and independent component analysis

The aim of this paper is the development of a bridge diagnosis system for daily bridge maintenance. The system includes the technology of wireless sensor network, signal processing, and structure analysis of a bridge. We collect the vibration data caused by external force such as wind pressure, running vehicles and etc through wireless sensor network and then use independent component analysis (ICA) and spectral analysis to analyze the data for extracting character frequency. The diagnosis technology is developed to understand the phenomena like deterioration and corrosion of a bridge through the measurement result. So the diagnosis system can evaluate the health condition of a bridge and conduct a comprehensive deliberation on repair and reinforcement work. We apply this diagnosis system to field experiments at Kokura, Kitakyushu city in Japan and successfully extract the character frequency of a bridge.

Detection of local sodium boiling in a simulated LMFBR fuel subassembly

Abstract Out-of-pile experiments were carried out to study the feasibility of the local sodium boiling detection by use of temperature, flow and acoustic noises. The studies showed that the temperature fluctuation transferred the information of local sodium boiling to the end of the bundle, but little to the outlet. A new anomaly detection method, which used the algorithm of whiteness test of the residual time series data of autoregressive model, especially using flow fluctuation, was effective detecting the anomaly such as local sodium boiling. On the other hand, acoustic noises with local sodium boiling became much higher than the background such as the mechanical and flow noises. A waveguide method, which was utilized for the present experiments, was useful for the boiling detection.

High-Precision Absolute Rotary Angular Measurement by Using a Multielectrode Circular Position-Sensitive Detector

We propose a multielectrode circular position-sensitive device that does not have any discontinuity in the detection region and has multiple electrodes for current output. We have also manufactured a prototype device. The device has a circular detection region that consists of photodiodes radially aligned with regular pitch and a resistance line connecting the outer edges of the photodiodes. All of the photocurrent excited in the photodiodes flows into the resistance line and is extracted from the electrodes connected to the resistance line at even intervals. There is no insensitive region for current output in this device since the detection region and the resistance line are separated; thus, detection with high resolution is possible at every angular position. We conducted a simulation of the detection characteristics and will propose a computational method for the position that uses four-electrode outputs in this paper. We confirmed that it is effective in minimizing the error from both the simulation and the experiment. We will also propose a measurement system of absolute angle using this method, confirming an error of less than 0.1° in the computation results.

Response calculation of a stacked CdZnTe detector for 16N γ-ray measurement

Abstract A stacked CdZnTe semiconductor detector, which is able to detect the 6.13 MeV γ-rays from 16 N, was prototyped and the response calculation was carried out by a Monte-Carlo simulation. The detector response was simulated by using the electron and photon transport code, EGS4 and taking into account the carrier trapping phenomena. The results of the response calculation agreed with the experimental data from the checking source of 137 Cs and 60 Co. The prototypes response and sensitivity to 16 N were calculated by simulating an incident energy of 6.13 MeV . The source spectra were unfolded with the detectors response function obtained by simulation, and it indicated that the incident γ-ray energy and its intensity ratio was identified. We have acquired the potential to measure the γ-ray energy in the high energy region about 6 MeV with the stacked CdZnTe detector.

Development of Bridge Diagnosis Technology by Independent Component Analysis

This paper focuses on maintaining a bridges safety by developing a daily management system. And the purpose of this study is the development of the health monitoring system. It supports the maintenance by independent component analysis (ICA) when there are some troubles in a bridge. The result of this study brings out the vibration behavior of the overall structure in a bridge. This vibration is caused by the external force such as heavy weight impact, wind pressure, and running vehicle. The character frequency was extracted from the analysis result using ICA and Spectral Analysis. When the vibration behavior caused by external force is very small in the bridge, ICA can detect the vibration response from the analysis result. Therefore, it is proved that the potential of detection was high by ICA

Improvement of the spectral response in large CdTe detectors operating at low bias voltage

This paper reports a method to improve the energy resolution for /spl gamma/ rays of a CdTe semiconductor detector 15 /spl times/ 15 /spl times/ 15 mm/sup 3/ in size and with low applied voltage and an adequate electronic circuit constant. The principle of improvement is to make use of carrier trapping and ballistic defects. We investigated the improvement of the energy resolution by calculating the output waveforms using a Monte Carlo simulation. As a result, we could obtain an approximately 8% energy resolution of 662 keV equivalent to that of an NaI(Tl) scintillator. Further, the intrinsic efficiency of a full energy peak equivalent to that of a 1-in-thick cylindrical NaI(Tl) scintillator could be achieved. This method has the advantages that the energy spectra can be improved by simple systems and the noise is reduced because of the low leakage current due to the low applied voltage.

Technology trends analysis from the internet resources

In business or technology planning, it is strongly required to grasp the overall technology trends and predict what will happen in the near future. In this paper, we propose the method where we can detect and analyze the technology trends from the Internet resources.

A foresight methodology for exploring prior R & D topics in software field: Calculation and resolution of conflicts

To reinforce the research development power, it is necessary to clarify the methodology of formulating the R&D strategies. This paper focuses on the methodology of setting the themes for R&D. We propose the NeXT model, which consists of two stages: foresight of the priority areas based on the conflicts between near-future trends and verifying the priority areas. We show a method for calculating a Degree of Conflict using FURPS+ model. The NeXT model comes in compliance with the characteristics of the current society in which the link between technology and society is stronger than ever before.

Development of Bridge Diagnosis System by Using Sensor Network and Independent Component Analysis

This paper focuses on maintaining a bridges safety by developing a daily management system. And the purpose of this study is the development of the health monitoring system. It supports the maintenance by using sensor network and Independent Component Analysis (ICA) when there are some troubles in a bridge. The result of this study brings out the vibration behavior of the overall structure in a bridge. This vibration is caused by the external force such as wind pressure, and running vehicle. The character frequency was extracted from the analysis result using ICA and Spectral Analysis. Even if the vibration behavior caused by external force is very small in the bridge, ICA can detect the vibration response from the bridge. The actual sensor network system has been developed and the performance is demonstrated.

A Methodology for Planning RaD Topics in IT Field

In order to reinforce the research development power in the software-related sectors, it is necessary to clarify the methodology of formulating the R&D strategies. This paper focuses on the methodology of setting the themes for R&D. In order to promote R&D more effectively, we propose the NeXT model which consists of two stages: forecasting the priority areas based on the conflicts between near-future trends and verifying the priority areas. We have evaluated this methodology by comparing with the results of the 7-th Technology Foresight which was conducted using the Delphi method. The NeXT model comes in compliance with the characteristics of the current society in which the link between technology and society is stronger than ever before, and is applicable to a wide range of fields.