A transponder-based positioning method using audible sounds for a large-scale area positioning has been proposed by the authors. The proposed method has two characteristics; it employs audible sounds instead of ultras...
A transponder-based positioning method using audible sounds for a large-scale area positioning has been proposed by the authors. The proposed method has two characteristics; it employs audible sounds instead of ultrasounds to measure long distance by using audible sounds, and it achieves positioning without clock synchronization among devices which is required additional equipment such as radio wave. However, positioning of the moving object (terminal) is still challenging because the proposed method requires longer measurement time than other methods since it measures the round-trip time of flight (TOF) among the terminal and the anchors (transponders). In this paper, we evaluated the effect of the terminal movement on positioning in simulations and experiments. From simulations and experimental results, it was found that the effect of doppler and the terminal movement cause random error and offset in TOF/distance, respectively. Consequently, it was found that our proposed method is sensitive to the terminal movement.
Individual thermal stress of people in physical training has not been evaluated quantitatively in real time. The main limitations in evaluating individual thermal stress are the difficulties in measuring individual th...
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ISBN:
(纸本)9781509023349
Individual thermal stress of people in physical training has not been evaluated quantitatively in real time. The main limitations in evaluating individual thermal stress are the difficulties in measuring individual thermal parameters, clothing insulation, and metabolic rate. In this study, we aimed to overcome these limitations with metabolic rate measurement. For calculating metabolic rate in real time without breath gas analysis, we proposed a derivation method from oxygen consumption and lung volume. We found that the deviation of chest size is proportional to the change of lung volume in each person, and the coefficient of determination was greater than 0.90.
Bone-conduction (BC) headphones are used when users need to hear provided sounds as well as environmental sounds since they do not occlude the environmental sounds. Sound localization characteristics of the BC sounds ...
Bone-conduction (BC) headphones are used when users need to hear provided sounds as well as environmental sounds since they do not occlude the environmental sounds. Sound localization characteristics of the BC sounds are usually worse than that of the air-conduction (AC) sounds. If the frequency characteristics of AC sounds can be reproduced with BC headphones, better sound localization with BC headphones can be achieved. To compensate the frequency characteristics difference between these sounds, a method to measure the frequency characteristics difference is proposed. Also, compensated BC sound is examined by localizing sounds. At first, the difference between AC and BC sounds are measured by tuning their amplitudes andphases to cancel at perceiving sound. The measurements were conducted for 30 frequencies in the audible range. Second, localization characteristics are measured in an anechoic chamber. The sounds are presented from AC and BC headphones using the corresponding head related transfer functions in the horizontal plane. Especially for the BC headphone, the characteristics difference between AC and BC are compensated. Based on single-user experiment, characteristic peaks were confirmed in the frequency characteristics difference. The more detailed experimental results with multiple number of users anddiscussions will also be provided.
In this paper, we evaluated the characteristics of the bone-conducted sound propagation in the human head through computer simulation using a reduced head model with finite element method. The model was made of three ...
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In this paper, we evaluated the characteristics of the bone-conducted sound propagation in the human head through computer simulation using a reduced head model with finite element method. The model was made of three spheres, which represent the skin, skull and brain, and the brain was represented by the water for simplicity. The step response of the head was investigated to show that the sound propagation would be generated in the form of longitudinal and bending wave through the head. From the simulation results, the sound speed of the longitudinal and bending waves were approximately 1500 m/s and 260 m/s, and the latter was compatible with the previously measured sound speed of bone-conduction.
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