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With the increasing use of wearable devices equipped with various sensors, information on human activities, biometrics, and surrounding environments can be obtained via sensor data at any time and place. When such devices are attached to arbitrary body parts and multiple devices are used to capture body-wide movements, it is important to estimate where the devices are attached. In this study, we propose a method that estimates the load positions of wearable devices without requiring the user to perform specific actions. The proposed method estimates the time difference between a heartbeat obtained by an ECG sensor and a pulse wave obtained by a pulse sensor, and it classifies the pulse sensor position from the estimated time difference. Data were collected at 12 body parts from four male subjects and one female subject, and the proposed method was evaluated in both user-dependent and user-independent environments. The average F-value was 1.0 when the number of target body parts was from two to five.

Wireless sensor networks have great potential to realize state observation in large scale areas. A ZigBee network is one of the world standards for short-range wireless sensor networks. Previous studies have proposed the application of Discrete binary Particle Swarm Optimization(DPSO), which is one of swarm intelligence algorithms, to sensor networks. However, DPSO has a problem that the performance deteriorates when the target problem becomes large scale. This paper proposes a new scheme that uses Angle Modulation based algorithms to detect the most effective allocation of routers in a ZigBee network. In the proposed scheme, an Angle Modulation function is applied to the search algorithm to generate a bit string for solving the binary problems. The performance of the proposed scheme is evaluated through simulation experiments.

Articles you may be interested inSimultaneous measurement of local longitudinal and transverse wave velocities, attenuation, density, and thickness of films by using point-focus ultrasonic spectroscopy A method to estimate the size of corrosion patches with guided waves in pipes.Evaluation of layer thickness in human teeth using higher-order-mode leaky Lamb wave interdigital transducers Rev. Sci. Instrum. 76, 036108 (2005); ABSTRACT. A noncontact method of an accurate estimation of a pipe wall thickness using a circumferential (C-) Lamb wave is presented. The C-Lamb waves circling along the circumference of pipes are transmitted and received by the critical angle method using a pair of noncontact air-coupled ultrasonic transducers. For the accurate estimation of a pipe wall thickness, the accurate measurement of the angular wave number that changes minutely owing to the thickness must be achieved. To achieve the accurate measurement, a large number of tone-burst cycles are used so as to superpose the C-Lamb wave on itself along its circumferential orbit. In this setting, the amplitude of the superposed region changes considerably with the angular wave number, from which the wall thickness can be estimated. This paper presents the principle of the method and experimental verifications. As results of the experimental verifications, it was confirmed that the maximum error between the estimates and the theoretical model was less than 10 micrometers.

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