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1

Symplectic singularities and solvable Hamiltonian mappings

Fukuda T., Janeczko S.

Demonstratio Mathematica

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2015

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Vol. 48, nr 2

118--146

EN

We study singularities of smooth mappings (…) of R2n into symplectic space (…) by their isotropic liftings to the corresponding symplectic tangent bundle (…). Using the notion of local solvability of lifting as a generalized Hamiltonian system, we introduce new symplectic invariants and explain their geometric meaning. We prove that a basic local algebra of singularity is a space of generating functions of solvable isotropic mappings over (…) endowed with a natural Poisson structure. The global properties of this Poisson algebra of the singularity among the space of all generating functions of isotropic liftings are investigated. The solvability criterion of generalized Hamiltonian systems is a strong method for various geometric and algebraic investigations in a symplectic space. We illustrate this by explicit classification of solvable systems in codimension one.

2

Dynamic PIV study of the turbulent flow field of several bi-leaflet mechanical mitral prostheses

Akutsu T., Fukuda T., Imai R., Saito J., Mori K.

Biocybernetics and Biomedical Engineering

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2007

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Vol. 27, no. 1-2

265-269

EN

Four mechanical bi-leaflet prostheses, the St. Jude Medical (SJM) valve and On-X (OX) valve with straight leaflets and the Jyros (JR) valve, and Edwards MIRA (MIRA) valve with curved leaflets were tested in the mitral position under pulsatile-flow conditions. Dynamic PIV system was employed to analyse the flow field affected by the leaflet shapes and overall valve designs. Detailed analysis of the time resolved information of the flow fields associated with the changing flow phases revealed the significance of the leaflet shape and overall valve designs on the flow field.

3

Time resolved PIV and LDA study of the turbulent flow field of bi-Ieaflet mechanical mitral prostheses

Akutsu T., Fukuda T., Sakurai S., Saito J.

Biocybernetics and Biomedical Engineering

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2006

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Vol. 26, no. 1

53-59

EN

Time Resolved PIV and LDA measurment were conducted for the study of the fIow field generated by the mechanical bi-leafIet mitral valves, the SJM and the Jyros valves, to find out the effect of the valve designs and the installed orientations on the fIow. Results from the time resolved PIV system were very comparable to the LDA results. In both orientations, the JR valve generated much higher turbulent stresses.

4

Growth and scintillation propertiesof Ce-doped PrF₃ single crystals

Kamada K., Yoshikawa A., Satonaga T., Sato H., Beitlerova A., Nikl M., Solovieva N., Fukuda T.

Opto-Electronics Review

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2004

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Vol. 12, No. 4

365-368

EN

The scintillation characteristics of the Ce-doped PrF₃ single crystals have been studied to find out their potential as for heavy scintillators. Crystal growth was performed in a vacuum-tight micro-pulling down (µ-PD) system. PrF₃ crystal was prepared with various concentrations (0, 0.1, 0.5, 1, 3, 5, 10, 20, 60, 80, 100%) of Ce³⁺. The crystals were transparent (CeF₃) or of greenish colour, 3 mm in diameter and 15-50 mm in length. Neither visible inclusions nor cracks were observed. At room temperature, the radio- and photoluminescence spectra and the decay kinetics were measured for the sample set.

5

Crystal growth of new functional materials for electro-optical applications

Fukuda T., Shimamura K., Yoshikawa A., Villora E. G.

Opto-Electronics Review

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2001

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Vol. 9, No. 2

109-116

EN

High quality fluoride and oxide single crystals for optical, piezoelectric, and other applications have been grown by advanced crystal growth techniques. Corquiriite- and Perovskite-type fluoride single crystals - LiCaAlF₆, LiSrAlF₆, KMgF₃ and BaLiFi₃ - have been grown for solid state ultraviolet laser applications, and as window materials for next generation optical lithography. La₃Nb₀.₅Ga₅.₅O₁₄ and La₃Ta₀.₅Ga₅.O₁₄ piezoelectric single crystals of size and quality comparable to La₃Ga₅SiO₁₄ (langasite) have been produced. The piezoelectric and device properties of the crystals were investigated. A search for new langasite-type materials was also performed. Promising new structural materials, Al₂O₃/RE₃Al₅O₁₂ (RE = rare earth) eutectic fibres, have been grown by the micro-pulling-down technique. Undoped and doped b-Ga₂O₃ single crystals have been grown by the floating zone technique as promising transparent conductive oxides.

6

Ecological model of Virus-Evolutionary Genetic Algorithm

Kubota N., Fukuda T.

Fundamenta Informaticae

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1999

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Vol. 37, Nr 1,2

51-70

EN

This paper deals with an ecological model on planer gird of a genetic algorithm based on vi-rus theory of evolution (E-VE-GA). In the E-VE-GA, each individual is placed on a planer grid and genetic operators are performed between neighborhoods. The E-VE-GA can self-adaptively change searching ratio between global and local searches. The main operator of the E-VE-GA is reserve transcription and incorporation transmitting local genetic information. The convergence of the E-VE-GA depends on the frequency and localization of the virus in-fection. In this paper, we apply the E-VA-GA to traveling salesman problems and discuss the coevolution of host and virus populations through the numerical simulation.

7

Implicit state estimators and their application to pole assignment controllers for systems with uncertainties

Chen X., Fukuda T.

Applied Mathematics and Computer Science

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1998

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Vol. 8, no 1

101-122

EN

This paper presents implicit robust state observers for SISO minimum phase dynamical systems with arbitrarily relative degrees (with respect to the relation between the disturbance and the output). For systems with relative degree one, the state is expressed by the filters of the input and the output. No apriori knowledge of the disturbance is required in this case. For systems with higher relative degrees, by first estimating the disturbance, the state vector is asymptotically expressed by the filters of the input, the filters of the output and the estimates of the first-order filters of the disturbance. Then the state observer and the estimated disturbance are applied to a controller to place desired poles and to cancel the disturbance. Finally, examples and simulation results show that the proposed algorithms are effective.