<p>Unmanned aerial vehicles (UAVs) domain has seen rapid developments in recent years. As the number of UAVs increases and as the missions involving UAVs vary, new research issues surface. An overview of the existing research areas in the UAV domain has been presented including the nature of the work categorised under different groups. These research areas are divided into two main streams: Technological and operational research areas. The research areas in technology are divided into onboard and ground technologies. The research areas in operations are divided into organization level, brigade level, user level, standards and certifications, regulations and legal, moral, and ethical issues. This overview is intended to serve as a starting point for fellow researchers new to the domain, to help researchers in positioning their research, identifying related research areas, and focusing on the right issues.</p><p><strong>Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 319-329, DOI: http://dx.doi.org/10.14429/dsj.65.8631</strong></p>
This research compares 3D versus 4D (three spatial dimensions and the time dimension) multi-objective and multi-criteria path-planning for unmanned aerial vehicles in complex dynamic environments. In this study, we empirically analyse the performances of 3D and 4D path planning approaches. Using the empirical data, we show that the 4D approach is superior over the 3D approach especially in complex dynamic environments. The research model consisting of flight objectives and criteria is developed based on interviews with an experienced military UAV pilot and mission planner to establish realism and relevancy in unmanned aerial vehicle flight planning. Furthermore, this study incorporates one of the most comprehensive set of criteria identified during our literature search. The simulation results clearly show that the 4D path planning approach is able to provide solutions in complex dynamic environments in which the 3D approach could not find a solution.Keywords: Unmanned aerial vehicles, UAV, path planning, modelling, simulation, 3D path planning, 4D path planning Vol. 66, No. 6, November 2016, pp. 651-664, DOI : 10.14429/dsj.66 , VOL. 66, NO. 6, NOVEMbER 2016 652 model used to create flight paths in 4D environment. The simulation model is more applicable and realistic compared to other studies examined during the literature review. The study includes the most comprehensive set of requirements including the ones overlooked in a wide range of studies. This study extends existing literature 1,3,20,21,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] by placing a special importance on aviation rules and utilisation considerations. The model generates suitable paths that address UAV performance limitations, environmental factors, basic aviation rules, flight dynamics, UAV utilisation considerations and user requirements. It helps in online and offline planning of optimal paths based on distance, fuel consumption, or time objectives, while implementing the described flight criteria. To build the simulation model (SM), we first built a conceptual model (CM) to structure the problem 68 . In the simulations, for each objective, various scenarios are created by changing the number of static and dynamic obstacles and target types. In each scenario, the path planning approach found the shortest and least costly flight paths. The path search is performed by A* heuristic algorithm proven to be complete and optimal. Additionally, in the experiments, A* algorithms with different heuristic parameters are compared using various scenarios in static and dynamic environments under different constraints. Since current UAVs have to make predictions and estimations about the possible future locations of mobile objects, the simulations also include path searches in time varying environments represented with a 4D grid. The 4D grid is constructed using a combination of 3D grids. Each 3D grid is a possible configuration of the world space at a specific time. A time-dimensional search space consider...
Although there have been several studies that focus on technical aspects of health monitoring systems, adoption of these systems remains largely unknown. A limited number of researches has explored the factors influencing users' adoption of these systems that provide successful system implementation. In this study, we reviewed articles addresses the adoption of health monitoring systems. We extract criteria that influence the adoption decision that has been made at some stage to use health monitoring systems. Then group these criteria into nine categories in terms of cost, ease of use, environment, knowledge, management, security, social influence, subjective norm, technical, usefulness, and enjoyment. By using these criteria, we develop an adoption model for health monitoring systems.
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