By capturing three dimensional motions of small markers on a heart of a small laboratory animal with 1000 fps stereo images, we realized a cardiac motion analysis system to quantify a rate of change of myocardial area on its heart, which indicates the myocardium's activity for rhythmic expansion/contraction motion in a local area. On the cardiac motion capture system, we actually analyzed three dimensional motion distributions of a heart of a rat model for myocardial infarction, whose heartbeat is 4 times/s or more. In the analysis, a characteristic cardiac motion in ischemic heart diseases was spatio-temporally quantified and visualized that infarction area on the heart of the rat caused by ischemia was spreading around its left ventricle.
This paper describes an oblique feed screw which can be used as load-sensitive continuously variable transmission (CVT). This CVT consists of a screw, spring, and bearing, and is remarkably simple and compact. Its reduction ratio change automatically in response to the load. We have developed the CVT of 13.8 [g]. We have experimentally verified that it can exert a very strong force of more than 100 [N], and the CVT can increase its reduction ratio form 20 to 45.
A rheometer was designed to measure the viscoelastic behavior of polymer melts and concentrated solutions at high temperature under high pressure. By means of this apparatus, the dynamic viscoelastic properties were measured of concentrated solution (20wt%) of polyisobutylene which had a viscosity-average molecular weight of 6.5×105 in decalin. Measurements were made at 40°C, frequencies being varied from 0.025 to 6.3 sec-1, under the pressure in the range from 0 to 1000kg/cm2.With the increase of pressure, both the dynamic viscosity and rigidity increased to the same extent as had been shown in the case of polymer melts. The time-pressure superposition, similar to the usual time-temperature superposition, was made to give a smooth master curve. In order to know how the shift factor depends on pressure, the iso-thermal compressibility of the same sample was determined at 40°C.From the above experiments the following conclusions can be made.(1) The specific volume of the solution can be related to the gauge pressure by Tait's equation, (1)where Vp and V0 are the specific volumes at gauge pressures P and 0kg/cm2 respectively. B and C are constants independent of pressure, and have the values of 760.7kg/cm2 and 0.1829 for the solution studied. Assuming that the relative free volume is defined as the ratio of the free volume to the occupied volume, the relative free volume of the solution was derived from Eq. (1), (2)where fp, fs and f0 are the relative free volumes of the solution at gauge pressures P, Ps (reference pressure) and 0kg/cm2, respectively.(2) Combining Eq. (2) with Doolittle's equation, the expression for the dependence of the shift factor on pressure can be derived as follows:(3)This expression shows satisfactory agreement with experimental results.
This study proposes a novel vision-based measurement method to capture small dynamic displacements at many points on a large-scale structure. The measurement points are aligned in the depth direction so that all points are observable in a single field of view with a high power zoom lens. To cope with insufficient incident light and lens blur when capturing video in a limited depth of field with large magnification, our method used highly retroreflective cubes as markers, combined with a strong coaxial lighting device for measuring image displacements with a tandem-layout in images. We conducted experiments to measure dynamic displacements of a 4 m long truss bridge model, and 18 corner cubes were attached as retroreflective markers. 752×2048 images were captured with a coaxial lighting device at 240 fps. The experimental results show that the deformation of the bridge model, its resonant frequencies, and mode shapes at a frequency of dozens of Hz can be determined by analyzing images captured from a single camera view.
By means of a high pressure rheometer designed to study the viscoelastic behaviour of polymeric liquids under high pressure, the viscosity of polystyrene (Mv; 1.88×105) solutions in toluene was measured over a wide range of concentration (c: 0.03-0.50) under various pressures up to 900 kg/cmcm2. The effects of pressure on the viscosity and critical concentration were discussed.The effect of pressure on the viscosity (logηp/ηo) above critical concentration cc was shown to increase with the increase of the concentration. Below cc, this effect was similar to that with the solvent and independent of the concentration. The log(ηp/ηo) was proportional to Pn. It is evident that these results can be described by combining the empirical equation and the viscosity equation proposed by Onogi.It is found also that cc is slightly shifted to lower concentrations with the elevation of pressure.
Flower stick juggling is a dexterous task done by skillful jugglers. We aim to realize dexterous tasks done by humans using robotic systems. This work focuses on flower stick juggling and proposes a feedback control strategy for a flower stick juggling task called "propeller" as one of the robotic dexterous manipulations. The propeller motion is modeled by considering combined flower stick and a robotic manipulator. We developed a control strategy that allows stable cyclic rotation of the flower stick in the air. Finally, the flower stick propeller motion is realized using an actual robotic system.
This study proposes a mobile robot that performs stable stepped travel with two driving wheels. Wheel movement is excellent in traveling efficiency, however it is not suitable for running on steps. In the past, we proposed a mechanism of a wheel type mobile robot which enabled a step running by using parallel linkage. This stair-climbing-robot had problems that the front wheel floated up and the body tilted during a step running. We focused on the thrust of the cylinder attached to the robot, and adjusted this value to obtain the condition for maintaining the contact between the wheel and the ground by the analysis based on the hydrostatics and verified by the experiment.
We propose a vibration imaging method for HFR-video-based localization of vibrating objects with large translations. When the ratio of the translation speed of a target to its vibration frequency is large, it is difficult to obtain its frequency response in image intensities because one or no waves are observable at the same pixel. Our method can precisely localize such moving objects with vibration by virtually translating multiple image sequences for pixel-level short time Fourier transform so that multiple waves are observable at the same pixel. Its effectiveness is demonstrated by analyzing several HFR videos for flying insects in real scenarios,
Equilibrium state phase diagrams in the MO-TeO2(M: Ba, Sr) systems were determined by DTA analysis and X-ray diffraction. T.T.T. (Time-Temperature-Transformation) and C.C.T. (Continuous-Cooling-Transformation) curves including various phenomena which occur on cooling the melts in glass-forming systems were determined by the hot-thermocouple method. The cooling rate and composition diagrams were made on the basis of the C.C.T. curves.Along with the development of the non-equilibrium and metastable materials, these diagrams are important as basic diagrams to develop new glassy materials by rapid cooling.
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