Journal of the Society of Biomechanisms
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Volume 18, Issue 2
Displaying 1-9 of 9 articles from this issue
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  • [title in Japanese]
    Nobutoshi Yamazaki
    Article type: Article
    1994 Volume 18 Issue 2 Pages 89-97
    Published: May 01, 1994
    Released on J-STAGE: October 31, 2016
    DOIhttps://doi.org/10.3951/sobim.18.89
    JOURNAL FREE ACCESS
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    Abnormal positions of the articular disc are frequently observed in the temporomandibular joint (TMJ) suffering dysfunctions. In this paper, we composed a mathematical model of the TMJ in sagittal plane and analyzed the behavior of the disc in open and close jaw motion. Bony structures and the disc which is divided into two pieces were assumed as rigid bodies. Principal six muscles and eight ligaments were attached on the structures. The position of the mandible and the disc at given jaw angles were calculated in order to minimize the sum of the muscle tensions. Abnormal disc positions were verified to be caused by the deterioration of joint surfaces, the displacement of centric occlusion, the elongation of ligaments, and the quick translation of mandibular head.
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  • [title in Japanese]
    Takeki Nakanishi, Keiji Saratani, Hisao Oka, Takayoshi Kawazoe
    Article type: Article
    1994 Volume 18 Issue 2 Pages 98-104
    Published: May 01, 1994
    Released on J-STAGE: October 31, 2016
    DOIhttps://doi.org/10.3951/sobim.18.98
    JOURNAL FREE ACCESS
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    The purpose of this study was to determine whether the Automatic Diagnostic System for tooth mobility we had developed was applicable for evaluating implant mobility. Ten IMZ implants, which had been functioning in the patients, were selected. Mechanical mobility of implant with intramobile element (IME) and titanium element, were measured by our system. The frequency spectrum of the mechanical mobility and mechanical parameters (c_1, c_2 and k) in implants were compared with those in natural teeth (maxillary central incisors and canines). Mechanical mobility spectra in implants were similar to those in teeth. The values of mechanical parameter in implants were larger than those in teeth. We found that the Automatic Diagnostic System could be utilized for evaluating implant mobility.
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  • AN APPLICATION OF OPTIMAL CONTROL THEORY FOR HEMODYNAMICAL CHANGES IN CARDIOVASCULAR SYSTEM EVOKED BY ALTERING AFTERLOAD IMPEDANCE
    Hirohumi HIRAYAMA, Norio TAKEUCHI, Yuzo FUKUYAMA
    Article type: Article
    1994 Volume 18 Issue 2 Pages 105-113
    Published: May 01, 1994
    Released on J-STAGE: October 31, 2016
    DOIhttps://doi.org/10.3951/sobim.18.105
    JOURNAL FREE ACCESS
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    An optimal control theory was applied to explain hemodynamical changes in cardiovascular system particularly with changes in afterload and work of ventricle. The performance function minimized involved the rate of change in aortic flow rate, external work, and potential energy of ventricle. The arterial system was expressed by wind kessel model with stroke volume constraint. Theoretical ventricular pressure and aortic flow curves coincided with reported experimental curves. The peak ventricular pressure increased with resistance and decreased with aortic compliance while the peak flow rate decreased with resistance and compliance which were consistent with reported experimental data. The regulation of the potential energy and the external work influenced seriously on aortic flow at any kind of afterload. Present investigation showed that cardiovascular system operates at least under the optimal control principle minimizing the work of ventricle and the rate of change in arterial flow.
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