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Post-IR IRSL dating of K-feldspar from last interglacial marine terrace deposits on the Kamikita coastal plain, northeastern Japan

Ito K., Tamura T., Tsukamoto S.

Geochronometria

2017

Vol. 44, no. 1

352--365

o establish a suitable luminescence dating protocol for marine terrace deposits in Japan, we tested the applicability of K-feldspar post-infrared (IR) infrared stimulated luminescence (IRSL) (pIRIR) dating using a marine isotope stage (MIS) 5e terrace deposit from the Kamikita coastal plain (NE Japan), where independent age control from a tephra is available. One of the most commonly used pIRIR signals, measured at 290°C with the first IR stimulation temperature at 50°C (pIRIR50/290), faded with a mean g2days value of 1.94 ± 0.19%/decade. In contrast, the pIRIR signal with a higher first IR stimulation temperature of 200°C (pIRIR200/290) had a much lower fading rate (g2days = 0.16 ± 0.49%/decade). The average fading-uncorrected and -corrected pIRIR200/290 ages of MIS 5e subtidal sediments obtained from two sampling sites were 126 ± 3 ka and 132 ± 2 ka, which is in good agreement with the independent age control. We conclude that is it is now possible to use pIRIR protocol to estimate the ages of not only marine terraces formed during MIS 5 substages (5a, 5c) but also of older marine terraces, for which age evidence is limited.

Characteristics of spiral vortex pump driven by two different drivers

Ito K., Sudo T., Shima T., Kouno Y., Ohnishi Y., Tanaka T., Iwasaki K., Fujimoto T., Umezu M.

Biocybernetics and Biomedical Engineering

2007

Vol. 27, no. 1-2

121-132

Here we describe a cardio-ventricular support system that combines a spiral vortex blood pump with an intra-aortic balloon pump driver. To reduce cost, we replaced the conventional ventricular assist driver with one used for an aortic balloon pump. We characterized the hydrodynamics of both drivers by recording pressure and flow waveforms during a single pulse for typical conditions of the pump. The pressure pulse of the ventricular assist driver was rectangular in shape, and the flow was maximal in the systolic fraction, when balanced conditions were achieved. By contrast, the triangle shaped pressure pulse of the balloon pump driver produced a constant volume. Flow increased in proportion to the rate of pulsation and drive volume. A minimum requirement set flow to 5 liters after 80 beats per minute. The balloon pump driver met the requirement with a 44 ml volume. Thus, the balloon pump driver effectively substituted for the ventricular assist driver. Our findings suggest that combining a spiral vortex pump with a balloon pump driver is cost-effective for left ventricular support during acute cardiac failure.

Adaptive compensators for pertrubed positive real infinite-dimensional systems

Curtain R. F., Demetriou M. A., Ito K.

International Journal of Applied Mathematics and Computer Science

2003

Vol. 13, no 4

441-452

The aim of this investigation is to construct an adaptive observer and an adaptive compensator for a class of infinite-dimensional plants having a known exogenous input and a structured perturbation with an unknown constant parameter, such as the case of static output feedback with an unknown gain. The adaptive observer uses the nominal dynamics of the unperturbed plant and an adaptation law based on the Lyapunov redesign method. We obtain conditions on the system to ensure uniform boundedness of the estimator dynamics and the parameter estimates, and the convergence of the estimator error. For the case of a known periodic exogenous input we design an adaptive compensator which forces the system to converge to a unique periodic solution. We illustrate our approach with a delay example and a diffusion example for which we obtain convincing numerical results.