Computational simulations which include three-dimensional (3-D) image processing and biomechanical calculations should provide useful information to our research and orthodontic clinic as a clinical tool defined as 'thinking'. In this review, 1) biomechanical simulations applied to predict the mandibular growth; 2) mathematical models of virtual bone cells and 3) 3-D images and solid model simulations for surgical planning are introduced. In biomechanical simulation, biting force, electromyographic (EMG) activity and cephalograms of 32 subjects were applied. Computational results of mathematical model were compared with actual bone growth in a rat. Three-dimensional image and solid model of 14 patients were utilized for their treatment planning. From the results, several concepts of our simulations were confirmed: 1) reaction forces generated by masticatory muscles at the condyle control the direction of mandibular growth; 2) some mathematical models have the possibility to describe the process of bone growth; 3) 3-D image processing software and solid models are necessary for diagnosis and planning of orthognathic surgery. We also believe that the orthodontists can more accurately predict the affects of surgical procedures and orthodontic tooth movement using the new cone beam X-ray computed tomography (CT) (CB MercuRay; Hitachi Medico Technology, Tokyo, Japan) and its advanced application software.
This paper describes group robots adaptively construct a mechanical structure. The feature of the robots is high rigidity by adopting sliding mechanisms. This study discusses algorithms of crawl motion and adaptive construction considering mechanical constraints of the robots. The proposed algorithm is based on local communication of the robots. We introduce a scheme of a temporary leader which is autonomously specified by form of the structure. The scheme decreases amount of information in communication between the robots. The experimental demonstrations are also shown in this paper.
In running cars or trains, passengers are often getting sleepy. We focus on this physiological phenomenon. If a machine can reproduce this phenomenon, it is feasible to put insomnia patients or infants to sleep without any harmful effects. This will bring extreme benefit for insomnia patients or parents of babies. The purpose of this study is to elucidate the sleep-inducing factors of running cars or trains, and the final goal is to develop a sleep inducing machine which reproduces the mechanical environment for sleep. For the first step, this study investigated the relationship between sleepiness and vibrations on several trains. The sleepability of each train is discussed by the ratio of sleeping passengers (RSP). High RSP trains can be recognized as comfortable to sleep. The acceleration profile of trains is analyzed by FFT and jerks. The results suggest that the comfortable train has mainly low-frequency (under 2.0 Hz) vibrations with particular fluctuation. Small jerk also contributes the sleepability. A prototype sleep inducing machine is tested with several subjects. The questionnaire survey indicates that near 1.0 Hz excitation is the most comfortable vibration for sleep. This result supports our hypothesis.
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