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The simulation capability for intraoperative brain tissue deformation by the surgical procedures using computational Finite Element analysis is demonstrated in this paper. Our research group has been developing the patient-specific three-dimensional Finite Element brain deformation model consisting of precise anatomical structures, i.e., brain parenchyma with both gyri and sulci on the surface, falx cerebri, and tentorium, in order to evaluate brain shift during navigation surgery without additional acquisition of intraoperative imaging. In this study, both gray and white matters of the brain tissues were modeled as homogeneous nonlinear hyper-viscoelastic material. The falx cerebri with tentorium was modeled as linear elastic material which is much stiffer than the brain tissue. The skull was modeled as a rigid body. In the numerical simulation, the computation of the intraoperative cerebellum tissue deformation due to retraction by spatula for posterior fossa surgery was conducted by ABAQUS/Explicit. The illustrative results successfully demonstrate the interaction between brain tissue and spatula.Copyright © 2007 by ASME

Recently, the brake noise reduction is one of the most important environmental issues for not only passengers both inside and outside train but also people who live close to railway stations. In this paper, a friction-induced self-excited oscillation and accompanying noise of a tread brake system are experimentally investigated by using a brake dynamometer. The squeal phenomenon occurs in the frequency range over 2000Hz by the test stand and generates high intensity noise up to 120dBA. In order to suppress brake squeal successfully, a simple oil damper attaching to the system is proposed. Since the proposed oil damper is a kind of Houde damper, damping augmentation capability is obtained in broadband of frequencies. The experimental brake test results demonstrate the brake squeal elimination capability of the proposed damper.Copyright © 2006 by ASME

Subsynchronous vibration of high-pressure steam turbine is one of the difficult problems to improve the reliability of power plant. Extensive work has been done to prevent the low frequency vibration of high-capacity steam turbine and most of the problems were practically solved[1][2]. In the future, we must build up theoretical approach to design a new turbine operating under the steam condition of high-temperature and high-pressure. To design such an advanced steam turbine, it is necessary to solve the effect of partial admission on control stage of the steam turbine. This paper describes the experimental results from the scale model of the steam turbine and theoretical analysis of Alford force considered partial admission condition to solve the problem. (1) Subsynchronous vibration was reproduced in the scale model test. (2) Partial admission gave larger destabilizing force compared with full admission condition for same total flow rate. (3) Initial position of shaft center to the phase of admission arc on the partial admission had some effect on the stability of the rotor system. (4) Theoretical analysis of destabilizing force considered partial admission condition gave qualitative description of the experimental results from the scale model.Copyright © 2005 by ASME

This paper presents some results of experiments and numerical computations on various aspects of vortex-structure interaction. Experimental tests were conducted in a small wind tunnel to investigate the effect of mechanical cylinder oscillation in the flow direction on the wake vortex structure. Depending on the excitation to Karman shedding frequency ratio, mode locked states, in the form of spatio-temporally repeatable patterns, could be observed. Symmetrical excitation leads to breaking of the Karman mode spatial-temporal symmetry. Depending on the excitation to Karman frequency ratio, modes lacking the usual Karman symmetry is observed. The existence of a stable spatio-temporal structure appears to be strongly dependent on the interaction (lock-in) between the near wake symmetrical shedding and the ‘established’ far wake Karman pattern. Preliminary work based on symmetry (group) theory is presented to support the foregoing experimental observations. By considering two oscillators having the Dm (κ,2π / m) inline shedding symmetry and the Karman wake having the spatio-temporal symmetry Z2 (κ,π), the possible symmetries of subsequent flow perturbations resulting from the modal interaction are determined. A mode having the reduced symmetry, Z2 (I,π2) was theoretically predicted and confirmed in the experiments. Finally, experimental tests show strong subharmonic lockin for forcing at rational ratios the vortex shedding frequency in the range 1 < m/n < 2. This phenomenon was also predicted theoretically.