Many studies for contact stress measurements on the human body have been conducted using thin and flexible sensors that can be attached to the skin. However, accurate stress measurements, including shear stress evaluations on the contact interface, have not yet been established. This study aims to improve a previously developed thin, flexible sensor capable of measuring three-dimensional vector information, including contact pressure and biaxial shear stress. The previous sensor had an overlapping structure with the upper and lower electrodes. However, the adhesion between the electrode layers was insufficient, resulting in a lack of stability during low-stress measurements. Therefore, a double-sided tape was used to strengthen the adhesion. Furthermore, the electrode shape was revised so that the measurement area of the sensor was downsized and suitable for high integration. The revised sensor was calibrated and found appropriate relationships among contact pressure, shear stress, and output voltage, including the low-stress range. To demonstrate the efficacy of the improved sensor, the sensor was attached to the scapula of a human body. The contact stress acting on the scapula was measured when the backrest of the bed was operated on while the person was lying on the nursing bed. Thus, the change in low contact stress in response to the posture change of the human body on the bed could be measured. The usefulness of the improved sensor was verified experimentally.

This paper describes a method to eliminate multipath effects by using the shield cover of a microwave absorber to improve Global Positioning System (GPS) positioning accuracy. We studied a walking movement support system for visually impaired people. The system provides audio guidance regarding the direction of movement and pedestrian signals based on the location of the intersection and the pedestrian’s GPS position. Because a pedestrian device is a wearable terminal, we want to obtain highly accurate location information with a simple mechanism that can be comfortably worn on the body. In this study, we propose a method using a shielding cover with a microwave absorber to improve the GPS positioning accuracy in environments where multipath, a major cause of positioning error, occurs. This method does not require any modification to the hardware or software of the GPS receiver, and the multipath is prevented by adjusting only the height and position of the shielding cover. In a walking experiment using the proposed method, we confirmed that the shielding plate, set at an open angle of 90 degrees, can provide positioning without being affected by multipath in an environment where there are buildings on both sides of the path.

A numerical study on the flow around a full-scale train subjected to crosswind has been conducted on the basis of detached-eddy simulation (DES). Finite-volume method is applied to unstructured mesh generated around a three-car-train model whose running speed is fixed to 120 km/h while the crosswind speed is set to 5 m/s,15 m/s, and 25 m/s. A clear longitudinal vortex structure is recognized in the case of the crosswind speed of 25 m/s, where two longitudinal vortices are evolved respectively from the roof and floor of the head car (roof-edge and floor-edge vortices), forming a characteristic vortex pair. This longitudinal vortex structure around the head car is discussed with a focus on its non-trivial role in the side-force mechanism. Our simulation suggests a causal association between these two vortices, which implies an importance of optimum designing of the underfloor equipment in addition to the roof and head shapes of the head car.

Much noise from the combustion oscillations and more are included in the measurement data for combustion experiments of micro-rocket torch. To develop the combustion gas measurement system for the micro-rocket torch using tunable diode laser absorption spectroscopy (TDLAS) method, we develop the denoising algorithms using the Savitzky-Golay filter and K-fold cross validation for improved noise-rejection capabilities. First, a validation study has been conducted on the gas measurement system using denoising algorithms in the case of atmospheric measurements. The atmospheric measurement results using denoising algorithms are in exceptionally good agreement with atmospheric conditions. Therefore, this result indicated that this algorithm gave satisfactory accuracies in the case of atmospheric measurements. Next, we investigated the combustion gas measurements for micro-rocket torch using the TDLAS method and demonstrated the usefulness of the denoising algorithms. From the results of this study, it is obvious that a significant accuracy improvement was obtained in the majority of absorbance spectrum cases with use of the denoising algorithms. Furthermore, the tendency of time-series torch gas temperature using TDLAS method is similar to the time-series estimated values.