Kenji Takahara

Design study of ultrahigh-speed microwave simulator engine

A design study of microwave simulator engine is presented in this paper. Taking note the simplicity and duality of data flow in finite-difference time-domain (FDTD) scheme, conceptual and hardware designs of the engine are shown for two-dimensional wave phenomena. To store field values in individual SRAMs, efficient use of digital hardware resources is achieved and the engine is constructed by very small size hardware. Based on the design study, a prototype hardware is made and basic operation is confirmed.

Automatic control of respiration to deal with difference of individual characteristics

Abstract A clinical technology generally consistent with a difference of individuals is discussed on the basis of adaptive control theory taking into account the automatic control of alveolar CO 2 -concentration in both controlled- and assisted-respiration. An experimental system for this purpose is proposed which consists of a newly developed respirator and controlling and measuring devices. Its control system requires safe and accurate operation in the different experimental environments in controlled- and assisted-respiration, which are characterized by pattems of ventilatory rhythms. In order to satisfy both requirements, a control system is designed on the basis of an adaptive pole assignment method, which is capable of compensating characteristic and environmental changes of a controlled object. It yields, thus, a stable control of alveolar CO 2 -concentration dealing with some disorder of the equipment, mainly with the different characteristics of a respiratory regulation system inclusive of its individual difference such as nonlinearity and chronic change. From clinical experiments on healthy subjects, the performance of the control system is confirmed to follow-up a given desired alveolar CO 2 -concentration with assurance of its clinical safety. This kind of adaptive control is confirmed to lead to the useful concept and method for the control of an organic function relied upon its less exact recognition because of its time-varying and ambiguous characteristics.

Analysis and measurement of damping characteristics of linear generator

The purpose of this study is to analyse and to measure damping characteristics of a linear generator. The linear generator can convert any mechanical vibration to electric power. The damping characteristics of the linear generator change due to the changes of the connected resistance. Therefore, a linear generator can be used as a controllable damper. The viscous damping coefficients were calculated by a finite element method. The prototype linear generator was produced based on the simulation and its damping characteristics were measured. It was confirmed that the viscous damping coefficient was controlled by PWM signal. Furthermore, the charging characteristics were measured when it mover was driven by constant vibration of amplitude 30 [mm] and frequency 3 [Hz]. It was conceivable that the proposed linear generator can be used as a generator or a controllable damper as necessary.