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Recently, the maintenance and management of infrastructure, such as paved roads and bridges, at a low cost has become important. Although some measurement methods including the falling weight deflectometer test have been developed to assess the soundness of paved roads, it is difficult to measure the data in a constant manner, for instance, on a daily basis. Therefore, we present an approach as per which we install vibration sensors on paved roads and automatically detect the deterioration of the paved roads via the installed vibration sensor and a machine-learning technique.Deterioration detection techniques that exploit vibration sensors have been studied; however, those were limited to bridge monitoring. No studies for the vibration measurement of paved roads using fixed sensors have been conducted. Herein, we focus on the deterioration of paved roads, specifically, in the form of road cracks, and conduct vibration measurements that highlight the differences in the vibrations of roads with and without cracks.In this paper, we describe the vibration measurements of a paved road with and without cracks and propose a framework for detecting cracks. An anomaly detection technique is necessary for using our detection framework. In this paper, we also evaluate the detection performance using anomaly detection techniques—namely, one-class support vector machine, isolation forest, and local outlier factor—using the measured vibration data.

Recently, hybrid vehicles (HVs) have become widespread. In the current HVs, a high-voltage (200 V) battery supplies power to the Power Control Unit (PCU) for driving a motor, generator and air conditioner compressor. It is expected that such kinds of power electronic devices will increase in number in the future. We previously proposed a power line communication (PLC) that uses a high-voltage power line. In this paper, we present the development of a high-voltage PLC system that can simultaneously control multiple power electronic devices in real time and demonstrate the system operation. First, in a system of a commercially available HV, the results of transmission characteristics and electromagnetic noise characteristics that are superimposed on the high-voltage power line are shown. Then the bit error rate (BER) performance under the above noise environment is clarified by computer simulations. Finally, we construct a prototype of the high-voltage PLC system and demonstrate that the system can simultaneously control the rotational speed of two motors.

The artificially generated noise from the appliances has a periodicity in frequency domain. A noise suppression system, which is based on the PI(Power Inversion) algorithm and using frequency shift, has already been proposed. However, the system has a significant problem that the suppression effect can not be obtained when the frequency shift is not accurate. In this paper, reduction method of frequency shift error is proposed. Numerical results show that frequency shift error is reduced by the proposed method when the number of snapshots and the interval of sampling are set appropriately.

The noise-related phenomenon, stochastic resonance (SR), may improve the performance of signal detection devices. In digital signal processing, the effect of SR depends on the observation time and sampling frequency. To apply it to digital signal processing, these two parameters must be determined. This paper investigates the observation time and sampling frequency for efficient SR in a digital system.

Efficient detection of a weak signal in a noisy environment is one of the most intensely studied topics in signal processing. In such research, the concept of a noise-induced giant response, such as occurs in stochastic resonance, has attracted a great deal of attention. In the present study, by analyzing a system subjected to a deterministic fluctuation, we show that the occurrence of a giant response is strongly related to instability in the system. We derive the response function of the system, and obtain its eigenfunctions which determine the response behavior of the system. We find that the maximum eigenvalue of the response function diverges when instability arises in the system, and the infinite eigenvalue gives rise to a giant response. Our approach is analogous to the well-established fluctuation-response theory, and can be easily extended to a system with purely stochastic fluctuations.

In the decentralized-TDMA (D-TDMA) protocol the terminals select a free slot based on the frame information (FI) included in each packet to be transmitted. However, the FI constitutes a large portion of the packet which seriously compromised the throughput of the D-TDMA. We are proposing a technique for increasing the throughput by reducing the length of the FI without jeopardizing the packet success rate. Our technique, which is based on FI redundancies, lets the terminals transmit the relevant information when necessary. A computer simulation was conducted for an urban environment in which vehicles are moving. The simulation results show that the proposed technique significantly increases the throughput without degrading the quality of the D-TDMA protocol.

An inter-vehicle communication system is highly advantageous for driving safety support systems, such as collision avoidance systems at intersections. In an inter-vehicle communication system, a channel-tracking scheme is essential to achieve reliable wireless communication under the fast fading environment caused by surrounding vehicles. For coherent detection, decision feedback is a well-known channel-tracking scheme. In this scheme, replica signals are generated and channel estimation is performed by using the replica signals. However, because channel estimation performance depends on the signal-to-noise (SNR) at symbol time, decision feedback errors occur by the lower SNR caused by fast fading. The feedback errors degrade the transmission performance significantly. In an orthogonal frequency division multiplexing (OFDM) system, the time domain 0-padding scheme is a well-known channel estimation technique. Although better channel tracking performance is expected by applying the 0-padding scheme, the tracking performance is degraded when employing guard-bands in the OFDM system. In this paper, we propose an improved time domain 0-padding scheme for an STBC-OFDM system employing guard-bands based on the IEEE802.11p standard for inter-vehicle communication, and show the improved performance through computer simulations.

The UWB-IR (ultra wideband-impulse radio) technology and MIMO system have attracted interest for next generation high rate radio communications. The authors researched IMO-UWB systems using the FDE (frequency domain equalization) technique with the MMSE spatial filtering technique. The UWB system will be used in short range wireless transmissions. Then, we usually have line-of-sight (LOS) environments in the MIMO-UWB systems. The authors conducted propagation measurement and evaluated the transmission performance of MIMO-UWB systems in LOS environments. Then, the authors proposed a timing control scheme for performance improvement. SIC (successive interference canceller) and PIC (parallel interference canceller) are known as better signal separation techniques in MIMO systems. In these techniques, the authors obtain diversity gain subtracting the data detected by a spatial filtering technique from the received signal. Therefore, we can achieve better signal separation performance by the diversity gain. The authors found that the timing control scheme is also needed for the SIC and PIC techniques in LOS MIMO-UWB environments by bit error rate (BER) evaluation. In this paper, the authors show the signal separation performance applying the SIC and PIC techniques with the timing control scheme in LOS environments.