Balloch, AS, Meghji, M, Newton, RU, Hart, NH, Weber, JA, Ahmad, I, and Habibi, D. Assessment of a novel algorithm to determine change-of-direction angles while running using inertial sensors. J Strength Cond Res 34(1): 134–144, 2020—The ability to detect and quantify change-of-direction (COD) movement may offer a unique approach to load-monitoring practice. Validity and reliability of a novel algorithm to calculate COD angles for predetermined COD movements ranging from 45 to 180° in left and right directions was assessed. Five recreationally active men (age: 29.0 ± 0.5 years; height: 181.0 ± 5.6 cm; and body mass: 79.4 ± 5.3 kg) ran 5 consecutive predetermined COD trials each, at 4 different angles (45, 90, 135, and 180°), in each direction. Participants were fitted with a commercially available microtechnology unit where inertial sensor data were extracted and processed using a novel algorithm designed to calculate precise COD angles for direct comparison with a high-speed video (remotely piloted, position-locked aircraft) criterion measure. Validity was assessed using Bland-Altman 95% limits of agreement and mean bias. Reliability was assessed using typical error (expressed as a coefficient of variation [CV]). Concurrent validity was present for most angles. Left: (45° = 43.8 ± 2.0°; 90° = 88.1 ± 2.0°; 135° = 136.3 ± 2.1°; and 180° = 181.8 ± 2.5°) and Right: (45° = 46.3 ± 1.6°; 90° = 91.9 ± 2.2°; 135° = 133.4 ± 2.0°; 180° = 179.2 ± 5.9°). All angles displayed excellent reliability (CV < 5%) while greater mean bias (3.6 ± 5.1°, p < 0.001), weaker limits of agreement, and reduced precision were evident for 180° trials when compared with all other angles. High-level accuracy and reliability when detecting COD angles further advocates the use of inertial sensors to quantify sports-specific movement patterns.

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One of the major challenges in wireless sensor networks (WSNs) deployment is to decrease sensor node\u27s energy consumption to prolong the lifetime of the finite-capacity batteries. Using multihop has been viewed as one of the main techniques to prolong operational lifetime in wireless sensor networks. In this paper we offer a study on transmission power control (TPC) in multihop WSNs using typical Telosb platform parameters, which is IEEE 802.15.4 standard compliant. We offer a new approach to test TPC in multihop networks at the physical layer and provide energy consumption performance results via simulation and numerical model in multihop WSNs. Our simulation and numerical model results illustrate that energy spent to send packets using short-range multihop path instead of single hop does not necessarily save energy as suggested by some of the earlier research

A key aspect of a wireless sensor network is its ability to self-organize and maintain connectivity. Medium Access Control (MAC) protocol manages network self-configuration, which includes establishing a personal area network (PAN), finding a network to associate or disassociate with, and synchronizing if required. Currently, there is limited research that addresses the network initialization phase. This paper provides a performance evaluation of the 802.15.4 MAC during device association and synchronization with the PAN coordinator. Our results show the impact of beacon interval and the number of associating nodes in terms of association time delay and energy consumption in stationary wireless sensor networks. Results illustrate that energy consumption and association time increase with increasing number of nodes associating with a coordinator. Moreover, short beacon intervals consume more energy due to the frequency of beacon frames that nodes have to keep track of to maintain synchronization. However, short beacon intervals reduce the time required for the nodes to associate, in contrast to longer beacon intervals that are undesirable for real time and mobile applications. Furthermore, for longer beacon intervals, BO= 12 to BO=14, there is an abrupt increase in energy consumption as the number of associating nodes increase, even for as few as as four nodes