This paper analyzes the bifurcation phenomena related to chaotic attractors in an interrupted electric circuit with thermoelectric characteristics. In this work, composite return maps and the invariant intervals of the system are considered in order to calculate the bifurcation points of the chaotic attractors. This work focuses on a simple circuit that simulates the switching action of the current-mode-controlled DC–DC converter; as a result of considering this simple model circuit, a detailed analysis of the chaotic attractors leading to exact solutions is possible. The conditional equations used in the calculation of the bifurcation curves are completely derived, and the bifurcation structure of the system is established.

In factories that handle metals, steel, and other materials, the noise produced by machinery and manufacturing processes is called noise owing to its loudness and high frequency. Earplugs are primarily used to prevent noise-induced hearing loss. However, because earplugs block out all external sounds, including work conversations and warning sounds, there is a need for earphones (earplugs) that can selectively allow essential sounds, such as speech and danger alerts, to pass through while blocking other external noises. We propose a method for discriminating whether a signal contains speech using a bilateral clamper. In this study, the noise-only regions did not produce any output, making the earphones function similarly to regular earplugs. The signal containing the voice is subjected to noise reduction by a low pass filter.

Existing robots are realized with embedded control. This makes it difficult to operate in unknown environments where environmental information cannot be obtained in advance. The objective of this research is to construct a control system for a robot that can reliably carry out its work objectives in an unknown environment. Implementing environmentally adaptive behavior requires a simultaneous discussion of the uncertainty of the environment perceived by the robot and the robot's chosen behavior. We propose a method to design robot behaviors according to sensor information and make this a single layer. The function to be achieved by the control system design at each layer is considered the work objective. The actions from multiple layers are stratified according to the sequential relationship of the work objectives. This paper describes the results of applying layered control based on sensor information to a wheeled robot and a quadrotor helicopter. Numerical simulations and experiments confirmed that target tracking can be achieved while avoiding obstacles. The next task is to construct a hierarchy of flying robots as an extension of wheeled robots.