Microdrone-Based Indoor Mapping with Graph SLAM

Unmanned aerial vehicles offer a safe and fast approach to the production of three-dimensional spatial data on the surrounding space. In this article, we present a low-cost SLAM-based drone for creating exploration maps of building interiors. The focus is on emergency response mapping in inaccessible or potentially dangerous places. For this purpose, we used a quadcopter microdrone equipped with six laser rangefinders (1D scanners) and an optical sensor for mapping and positioning. The employed SLAM is designed to map indoor spaces with planar structures through graph optimization. It performs loop-closure detection and correction to recognize previously visited places, and to correct the accumulated drift over time. The proposed methodology was validated for several indoor environments. We investigated the performance of our drone against a multilayer LiDAR-carrying macrodrone, a vision-aided navigation helmet, and ground truth obtained with a terrestrial laser scanner. The experimental results indicate that our SLAM system is capable of creating quality exploration maps of small indoor spaces, and handling the loop-closure problem. The accumulated drift without loop closure was on average 1.1% (0.35 m) over a 31-m-long acquisition trajectory. Moreover, the comparison results demonstrated that our flying microdrone provided a comparable performance to the multilayer LiDAR-based macrodrone, given the low deviation between the point clouds built by both drones. Approximately 85 % of the cloud-to-cloud distances were less than 10 cm

Biodiesel production from Caulerpa racemosa (macroalgae) oil

616-621In the present investigation, non-edible toxic oils from marine macroalgae Caulerpa racemosa species, richly available in India and composed of high calorific value and high FFA, have been selected as a feedstock for the making of biodiesel. Initially, oil extraction was carried out from the macroalgae biomass with different types of solvent systems and extraction steps. The algal oil was extracted with a solvent system consisting of 1 % diethyl ether and 10 % methylene chloride in n-hexane using ultrasonic pre-treatment technique. The algal oils were characterized by Gas Chromatography-Mass Spectrometry for composition analysis. The biodiesel was produced by transesterification method. The produced biodiesel was characterized and the conversion was calculated by Fourier-transform infrared spectroscopy (FTIR) analysis and Response Surface Methods. The fuel properties of obtained biodiesel were examined as per the American Standard Test Methods specifications in order to assess the potential of proposed biodiesel as an alternative fuel. Thus, marine macroalgae serve as a potential renewable raw-material for biodiesel production