Optimal energy efficient path planning of UAV using hybrid MACO-MEA* algorithm: theoretical and experimental approach.

Autonomous mission capabilities with optimal path are stringent requirements for Unmanned Aerial Vehicle (UAV) navigation in diverse applications. The proposed research framework is to identify an energy-efficient optimal path to achieve the designated missions for the navigation of UAVs in various constrained and denser obstacle prone regions. Hence, the present work is aimed to develop an optimal energy-efficient path planning algorithm through combining well known modified ant colony optimization algorithm (MACO) and a variant of A*, namely the memory-efficient A* algorithm (MEA*) for avoiding the obstacles in three dimensional (3D) environment and arrive at an optimal path with minimal energy consumption. The novelty of the proposed method relies on integrating the above two efficient algorithms to optimize the UAV path planning task. The basic design of this study is, that by utilizing an improved version of the pheromone strategy in MACO, the local trap and premature convergence are minimized, and also an optimal path is found by means of reward and penalty mechanism. The sole notion of integrating the MEA* algorithm arises from the fact that it is essential to overcome the stringent memory requirement of conventional A* algorithm and to resolve the issue of tracking only the edges of the grids. Combining the competencies of MACO and MEA*, a hybrid algorithm is proposed to avoid obstacles and find an efficient path. Simulation studies are performed by varying the number of obstacles in a 3D domain. The real-time flight trials are conducted experimentally using a UAV by implementing the attained optimal path. A comparison of the total energy consumption of UAV with theoretical analysis is accomplished. The significant finding of this study is that, the MACO-MEA* algorithm achieved 21% less energy consumption and 55% shorter execution time than the MACO-A*. moreover, the path traversed in both simulation and experimental methods is 99% coherent with each other. it confirms that the developed hybrid MACO-MEA* energy-efficient algorithm is a viable solution for UAV navigation in 3D obstacles prone regions.

Visible Active N-Doped TiO2/WS2 Heterojunction Nano Rods: Synthesis, Characterization and Photocatalytic Activity.

N-doped titania nano sheets and N-doped titania/tungsten dioxide nano rods were synthesized by two step hydrothermal method. The composition, structural, functional, morphological and optical properties of the as synthesized N-TiO2/WS2 hybrids were characterized by XRD, UV-DRS, PL, FE-SEM with EDAX, TEM, FT-IR and Raman spectroscopy. Surface area and thermal stability of the catalysts were analyzed by BET and TG/DTA techniques. The photocatalytic activity of the heterojunction catalyst was evaluated towards the decomposition of a harmful dye namely congo red in an aqueous solution under visible light irradiation. The results show superior photocatalytic activity for N-TiO2/WS2 nanocomposite. This unusual photocatalytic activity is attributed to the synergistic effect between WS2 and N-TiO2.

Photocatalytic Degradation of Reactive Dyes Over Titanates.

MTiO3 (M = Sr, Ca, Ba and Pb) catalysts were synthesized by polymeric precursor method and characterized by using various instrumental techniques such as X-ray diffraction (XRD), UV-diffuse reflectance spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). TiO2 were also synthesized by sol-gel method and used for the optimization of reaction parameters such as catalyst weight, dye concentration and pH in the photocatalytic degradation of reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) under UV irradiation. MTiO3 (M = Sr, Ca, Ba and Pb) catalysts were evaluated towards the photocatalytic decolourization of RB 198, RB 5 and RY 145 under optimized reaction conditions. Among the different metal titanates, strontium titanate showed the highest decolourization (≈90%) of all the three reactive dyes under UV irradiation at 120 minutes and also found to be active under visible irradiation as it decolourises the dyes in about 450 minutes. The degradation rate of strontium titanate was monitored by TOC analyzer. Kinetic studies of the photocatalytic degradation of reactive dyes confirmed that the reaction followed the pseudo first order kinetics.