We study the role of energy conversion in phase regulation of frequency entrainment. For an open dynamical system that interacts with its environment, energy conversion in the system is the key to a wide variety of nonlinear phenomena including frequency entrainment. In this paper, using the standard notion of energy, we study the phenomena of frequency entrainment by periodic forces in two different types of oscillations: libration and rotation. Theoretical analysis shows a relationship between phase regulation and energy conversion in the entrainment phenomena. Both of them are explained as a common phase regulation. On the other hand, no common relationship between transient behaviors and energy conversion is identified for the two different types of oscillations. For libration, the development of frequency entrainment does not depend on the energy conversion. The energy input to the oscillator affects the amplitude of libration. For the rotation, the development of frequency entrainment is governed by the amount of energy conversion. The energy input to the system directly regulates the phase of rotation, in other words, controls the entrainment phenomenon. These results suggest a different dynamical and control origin behind the two types of entrainment phenomena as the energy conversion in the systems.

In this paper, we describe detailed experimental demonstrations of blue/violet light generation by the injection of ultrashort optical pulses into photonic crystal fibers (PCFs). Two lightwaves appear one on each side of the injected pulses in the spectral domain. They simultaneously evolve in the PCFs, changing their center wavelengths so as to spectrally stand apart from each other. Such behaviors are explained on the basis of the theory of nonlinear optics. The final center-wavelength difference between the two lightwaves at the end of the PCFs, depending on the power density of the injected pulse, is increased up to a limit imposed by the PCFs. Owing to this increase, the shorter wavelength limit reaches approximately 400 nm, which shows that short-pulse injection in PCFs is a promising method of realizing simple blue/violet light sources.

This paper clarified fundamental aspects of both triboelectric processes and electrostatic discharge (ESD) phenomena to the electronic systems. A chance for ESD can occur if a charged metal object (steel piped chair, for example) contacts or collides with another metal objects at moderate speed. At metal-metal ESD event, the metal objects act as a radiation antenna in a very short time (some 100ps, for example) which emanates impulsive electromagnetic fields with unipolarity into the surrounding space. Because of ESD at low-voltage (3kV or less) conditions, the direction of electrons movement at the spark gap is always unidirectional and fixed. The spark gap works as a momentary switch and also as a "diode." The dominant fields radiated from the metal objects are impulsive electric fields or impulsive magnetic fields which depend on the metal object's electrical and geometric conditions. This impulsive electromagnetic fields penetrate electronic systems, causing electromagnetic interference (EMI) such as malfunctions or circuit upset. The difference between EMI actions in high-voltage ESD and low-voltage ESD is experimentally analyzed in terms of energy conversion/consumption. A series of experiments revealed that EMI actions due to the metal-metal ESD are not proportional to the charge voltage nor the discharge current. In order to capture single shot impulsive electromagnetic fields very close to the ESD point (wave source), a short monopole antenna as an ultra broad-band field sensor was devised. As for signal transmissions between the short monopole antenna and the instrument (receiver), micro/millimeter wave techniques were applied. The transmission line's minimum band width DC-18.5GHz is required for time domain measurements of low-voltage ESD.