Abstract:Permeability of a streambed is an important factor regulating nutrient and oxygen availability for aquatic biota. In order to investigate the relationship, an accurate permeability should be measured. However, it is difficult to measure permeability in a coarse gravel bed using a conventional permeability test. Moreover, turbulent flow may occur in coarse bed material, and then deviations from Darcy's law do occur. Thus, permeability calculated following Darcy's law may be overestimated under turbulent flow conditions and should be corrected. The packer test can be used in highly permeable gravel beds. We developed a field method applicable to a gravel bed using the packer test and derived an equation adopting a law of turbulent flow to study the problems under any type of flow condition. The accuracy of the equation was examined using a laboratory flume with a gravel bed. The results suggested that permeability calculated from Hvorslev's equation is overestimated for turbulent flow. In contrast, our equation, developed here, could evaluate permeability accurately under any type of flow condition.
Heat-induced gels were prepared from two di#erent types of frozen fish-meat (Surimi) to which rice starches had been added. All the stress-strain characteristics except yield strain of gel, prepared from second-grade Surimi, were enhanced to coincide with increases of the amount of starches added. At ,*ῌ addition, the breaking stress and strain reached the same levels as those of gel obtained from SA-grade Surimi. The addition of pregelatinized starches to SA-grade Surimi enhanced sti#ness of the gel, but decreased yield and breaking characteristics. Some characteristic values of gel added with-ῌ pre-gelatinized starches were proximal to those of gel added with +*ῌ Chinese yam.
Oral care is key to maintaining overall health. Elderly people and people with disabilities who require nursing care can have dif culty in brushing their teeth effectively and may require the assistance of a caregiver. However, to date, an effective method for teaching toothbrushing skills to caregivers and a training system that can be implemented in a non-in-person setting have not been established. Therefore, in this study, we developed a training simulator that enables skill acquisition while learning ideal brushing motion and force information from an arbitrary viewpoint in a virtual reality (VR) space. In this simulator, the position and orientation of the toothbrush as measured by six infrared cameras and the brushing force as measured by a small 6-axis force sensor are displayed in a VR space using computer graphics to match the visual information in the VR space with hand-force information in real space. The experiment was conducted in 10 healthy adults with no specialized skills or knowledge regarding oral care. They were trained to brush the cervical and distal parts of the maxillary central incisors while learning the ideal brushing motion shown by the computer graphics and the appropriate range of brushing force. Afterwards, skills were quanti ed in terms of brushing motion, brushing force, and plaque removal rate, and the overall effectiveness of the training was evaluated. The results showed that in cervical part brushing, the mean error between the participantsʼ brushing motion and the ideal brushing motion in the brushing direction improved from approximately 4.8 mm before training to 3.9 mm after training. In distal part brushing, the error improved from approximately 3.8 mm to 1.9 mm. Similarly, brushing force improved from approximately 0.8 N before training to the appropriate force of 1.5 N after training for both cervical and distal part brushing. The arti cial plaque removal rate improved from 40.3% to 68.7% for cervical part brushing and from 39.5% to 63.3% for distal part brushing, indicating the effectiveness of training using the proposed system. This simulator, which can simultaneously teach both brushing motion and brushing force, is expected to be developed as a new method for teaching toothbrushing skills to caregivers.
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