Anomalous response in the vicinity of spontaneous symmetry breaking

We propose a mechanism to induce negative AC permittivity in the vicinity of a ferroelectric phase transition involved with spontaneous symmetry breaking. This mechanism makes use of responses at low frequency, yielding a high gain and a large phase delay, when the system jumps over the free-energy barrier with the aid of external fields. We illustrate the mechanism by analytically studying spin models with the Glauber-typed dynamics under periodic perturbations. Then, we show that the scenario is supported by numerical simulations of mean-field as well as two-dimensional spin systems.Comment: 6 pages, 5 figure

Probabilistic safety assessment-based importance analysis of cyber-attacks on nuclear power plants

With the application of digital technology to safety-critical infrastructures, cyber-attacks have emerged as one of the new dangerous threats. In safety-critical infrastructures such as a nuclear power plant (NPP), a cyber-attack could have serious consequences by initiating dangerous events or rendering important safety systems unavailable. Since a cyber-attack is conducted intentionally, numerous possible cases should be considered for developing a cyber security system, such as the attack paths, methods, and potential target systems. Therefore, prior to developing a risk-informed cyber security strategy, the importance of cyber-attacks and significant critical digital assets (CDAs) should be analyzed. In this work, an importance analysis method for cyber-attacks on an NPP was proposed using the probabilistic safety assessment (PSA) method. To develop an importance analysis framework for cyber-attacks, possible cyber-attacks were identified with failure modes, and a PSA model for cyber-attacks was developed. For case studies, the quantitative evaluations of cyber-attack scenarios were performed using the proposed method. By using quantitative importance of cyber-attacks and identifying significant CDAs that must be defended against cyber-attacks, it is possible to develop an efficient and reliable defense strategy against cyber-attacks on NPPs

REMOTE SENSING OF WAVE DIRECTIONALITY BY TWO-DIMENSIONAL DIRECTIONAL WAVELETS: PART 1. THE DETECTION TOOLS OF DIRECTIONALITY IN SIGNALS

This paper presents the results of a study investigating methods of wave directionality based on wavelet transform. In part 1 of this paper, the theoretical background and characteristics of directional wavelet were discussed. Morlet wavelet and Cauchy wavelet were examined to test their efficiency in detection of directionality in signals. These wavelets were tested on numerical images which were considered to describe the basic characteristics of directionality of ocean waves

TRANSLATION THEOREMS FOR FOURIER-FEYNMAN TRANSFORMS AND CONDITIONAL FOURIER-FEYNMAN TRANSFORMS

Translation theorems for Wiener integrals were given by Cameron and Martin in [3] and by Cameron and Graves in [2]. Translation theorems for analytic Feynman integrals were given by Cameron and Storvick in [4], [7] and translation theorems for Feynman integrals on abstract Wiener and Hilbert spaces were given by Chung and Kang in [12]

Automatic Volume Control Based on Background Noise Characteristics

In this study, we propose a novel technique for automatic volume control (AVC). Contemporary AVC systems operate according to background noise level. This paper presentsan AVC system that adaptively updates the audio volumeconsidering the frequency characteristics of the background noise. From the experiments, we conclude that the developed techniques can be successfully used for various acoustic environments

REMOTE SENSING OF WAVE DIRECTIONALITY BY TWO-DIMENSIONAL DIRECTIONAL WAVELETS : PART 2. APPLICATIONS TO THE NUMERICAL AND FIELD DATA

This paper presents the results of a study investigating methods of interpretation of wave directionality based on wavelet transform. In part 1 of this paper, the tools to be used in detection of wave directionality, i. e., the Morlet and Cauchy wavelets, were described. This paper presents the application results of the directional wavelet to numerically generated images and video images taken in laboratory wave flume, river, and sea. The results showed that directional wavelet transform can be an efficient tool in detecting wave directionality with extremely low effort and cost when it is compared to traditional practices in use