Fall detection is a major challenge in the public healthcare domain, especially for the elderly as the decline of their physical fitness, and timely and reliable surveillance is necessary to mitigate the negative effects of falls. This paper develops a novel fall detection system based on a wearable device. The system monitors the movements of human body, recognizes a fall from normal daily activities by an effective quaternion algorithm, and automatically sends request for help to the caregivers with the patient’s location.

This study proposes a fast and stable recursive ellipsoidal state‐bounding‐based set‐membership estimation algorithm for the state estimation of linear system with unknown‐but‐bounded (UBB) disturbances. The proposed algorithm has a prediction–correction structure in time update and observation update, which is similar to Kalman filter. For both time update and observation update, there is a data‐depending weighting factor. The observation weighting factor is acquired by minimising the upper bound on a Lyapunov function of the posteriori estimation error. It has been demonstrated that the estimation error of the proposed algorithm is input‐to‐state stable when the system is uniformly observable. With the property of selective observation update, the proposed algorithm not only improves the point estimation accuracy but also decreases the computation load of observation weighting factors and the volume of feasible ellipsoid sets. The efficiency of the proposed algorithm has been demonstrated by numerical simulations with different UBB disturbances.

Understanding, analysis, monitoring and modelling of urban expansions are most important for urban planners in the process of sustainable development. This article investigated spatio-temporal process of urban expansion using cellular automata (CA) model integrated with artificial neural network (ANN) method. This integrated model was calibrated with data from 1974 to 2018, and used to predict expansions for 2030 and 2040 with two datasets of explanatory variables including slope, forest, river, specially protected areas, road, railroad and urban centres in an urban and non-urban area. The urban suitable area was estimated by criteria evaluation weights and analytic hierarchy process (AHP). The results show that the urban growth of Ulaanbaatar was equal to +36,201 ha (84.8%) for the period of 1974–2018 and this city will be projected to reach approximately +43,111 ha by 2030 (+50.3% from 2018) and +111,441 ha by 2040 (+44.3% from 2030 and totally +72.3% from 2018).

This work investigates the ionospheric response to the March 2023 geomagnetic storm over American and Asian sectors from total electron content (TEC), rate of TEC index, ionospheric heights, Swarm plasma density, radio occultation profiles of Formosat-7/Cosmic-2 (F7/C2), Fabry-Perot interferometer driven neutral winds, and E region electric field. During the storm’s main phase, post-sunset equatorial plasma bubbles (EPBs) extend to higher latitudes in the western American longitudes, showing significant longitudinal differences in the American sector. Over the Indian longitudes, suppression of post-sunset irregularities is observed, attributed to the westward prompt penetration electric field (PPEF). At the early recovery phase, the presence of post-midnight/near-sunrise EPBs till post-sunrise hours in the American sector is associated with the disturbance of dynamo-electric fields (DDEF). Additionally, a strong consistency between F7/C2 derived amplitude scintillation (S4) ≥ 0.5 and EPB occurrences is observed. Furthermore, a strong eastward electric field induced an increase in daytime TEC beyond the equatorial ionization anomaly crest in the American region, which occurred during the storm’s main phase. Both the Asian and American sectors exhibit negative ionospheric storms and inhibition of ionospheric irregularities at the recovery phase, which is dominated by the disturbance dynamo effect due to equatorward neutral winds. A slight increase in TEC in the Asian sector during the recovery phase could be explained by the combined effect of DDEF and thermospheric composition change. Overall, storm-time ionospheric variations are controlled by the combined effects of PPEF and DDEF. This study may further contribute to understanding the ionospheric responses under the influence of storm-phase and LT-dependent electric fields.

Quadrotors are gaining an increasing interest in public and extensively explored in recent years. In many situations, a team of quadrotors is desired to operate in a certain shape, which is also called formation. In this paper, a linear PID controller is used to control each single quadrotor and a slide mode controller is adopted to solve the formation flying problem which employs the leader-follower structure. The formation simulations are run in the Matlab/Simulink environment to evaluate the performance of control laws.