Evaluating the Correlation between Thermal Signatures of UAV Video Stream versus Photomosaic for Urban Rooftop Solar Panels

The unmanned aerial vehicle (UAV) autopilot flight to survey urban rooftop solar panels needs a certain flight altitude at a level that can avoid obstacles such as high-rise buildings, street trees, telegraph poles, etc. For this reason, the autopilot-based thermal imaging has severe data redundancy—namely, that non-solar panel area occupies more than 99% of ground target, causing a serious lack of the thermal markers on solar panels. This study aims to explore the correlations between the thermal signatures of urban rooftop solar panels obtained from a UAV video stream and autopilot-based photomosaic. The thermal signatures of video imaging are strongly correlated (0.89–0.99) to those of autopilot-based photomosaics. Furthermore, the differences in the thermal signatures of solar panels between the video and photomosaic are aligned in the range of noise equivalent differential temperature with a 95% confidence level. The results of this study could serve as a valuable reference for employing video stream-based thermal imaging to urban rooftop solar panels.

Performance Assessment of Thermoelectric Generators with Application on Aerodynamic Heat Recovery

Based on thermoelectric generators (TEGs), an aerodynamic heat energy recovery system for vehicle is proposed. A mathematical model describing the energy conversion law of the system is established, and the integrated calculation method which combined aerodynamic heating and thermoelectric (TE) conversion is given. Furthermore, the influences of the typical flight Mach number, flight altitudes and the length of TE legs on the energy conversion behavior of energy recovery systems are investigated. The performance of the energy recovery system is analyzed and evaluated. The results show that, the decrease of flight altitude and the increase of Mach number will obviously improve the performance of the heat energy recovery system with TEGs. The increase of leg length will increase the temperature of the hot end of TEGs and reduce the heat absorbed at the hot end. When the external load, Mach number and flight altitude is fixed, there exists an optimal length of legs corresponding to the maximum output power and maximum conversion efficiency of the system. The results will have significant positive impact on thermal protection and management of supersonic / hypersonic vehicles.

Flight altitude dynamics of migrating European nightjars across regions and seasons

Avian migrants may fly at a range of altitudes, but usually concentrate near strata where a combination of flight conditions is favourable. The aerial environment can have a large impact on the performance of the migrant and is usually highly dynamic, making it beneficial for a bird to regularly check the flight conditions at alternative altitudes. We recorded the migrations between northern Europe and sub-Saharan Africa of European nightjars Caprimulgus europaeus to explore their altitudinal space use during spring and autumn flights and to test whether their climbs and descents were performed according to predictions from flight mechanical theory. Spring migration across all regions was associated with more exploratory vertical flights involving major climbs, a higher degree of vertical displacement within flights, and less time spent in level flight, although flight altitude per se was only higher during the Sahara crossing. The nightjars commonly operated at ascent rates below the theoretical maximum, and periods of descent were commonly undertaken by active flight, and rarely by gliding flight, which has been assumed to be a cheaper locomotion mode during descents. The surprisingly frequent flight-altitude shifts further suggest that nightjars can perform vertical displacements at a relatively low cost, which is expected if the birds can allocate potential energy gained during climbs to thrust forward movement during descents. The results should inspire future studies on the potential costs associated with frequent altitude changes and their trade-offs against anticipated flight condition improvements for aerial migrants.

Przewalski’s Horses (Equus ferus przewalskii) Responses to Unmanned Aerial Vehicles Flights under Semireserve Conditions: Conservation Implication

Recent technological innovations have led to an upsurge in the availability of unmanned aerial vehicles (also known as drones and hereafter referred to as UAVs)—aircraft remotely operated from the ground—which are increasingly popular tools for ecological research, and the question of this study concerns the extent to which wildlife responses might allow aerial wildlife monitoring (AWM) by UAVs. Our experiment tests the hypothesis that the wildlife-UAVs interaction depends strongly on flight altitude that there may be a lowest altitude range for which the ungulates are not exceedingly disturbed, dictating a practically achievable level of discernibility in flight observation, for this question might influence the future viability of the UAVs in the study and protection of the other wildlife in China’s semiarid ecosystem. We examined the behavioral responses of a group of enclosed Przewalski’s horses (Equus ferus przewalskii) to the presence of different in-flight UAVs models by conducting flights at altitudes ranging from 1 to 52 meters and recorded the heights at which each horse reacted to (noticed and fled) the UAVs. All horses exhibited a stress response to UAVs flights as evidenced by running away. The results suggest strong correlations between flight altitude and response across the different subjects that adults generally noticed the UAVs at the larger heights (20.58 ± 10.46 m) than the immature (4.67 ± 0.87 m). Meanwhile, reaction heights of females (15.85 ± 6.01 m) are smaller than that of males (26.85 ± 18.52 m). Supported by their biological roles in herds (e.g., males must give protection to his entire herd while females are purely responsible for their offspring), our results also show that age, closely followed by gender, are the two most significant elements that determine a horse’s level of alertness to the UAVs. This research will help future scientists to better gauge the appropriate height to use a drone for animal observation in order to minimize disturbance and best preserve their natural behavior.

Appropriate Drone Flight Altitude for Horse Behavioral Observation

Recently, drone technology advanced, and its safety and operability markedly improved, leading to its increased application in animal research. This study demonstrated drone application in livestock management, using its technology to observe horse behavior and verify the appropriate horse–drone distance for aerial behavioral observations. Recordings were conducted from September to October 2017 on 11 horses using the Phantom 4 Pro drone. Four flight altitudes were tested (60, 50, 40, and 30 m) to investigate the reactions of the horses to the drones and observe their behavior; the recording time at each altitude was 5 min. None of the horses displayed avoidance behavior at any flight altitude, and the observer was able to distinguish between any two horses. Recorded behaviors were foraging, moving, standing, recumbency, avoidance, and others. Foraging was the most common behavior observed both directly and in the drone videos. The correlation coefficients of all behavioral data from direct and drone video observations at all altitudes were significant (p < 0.01). These results indicate that horse behavior can be discerned with equal accuracy by both direct and recorded drone video observations. In conclusion, drones can be useful for recording and analyzing horse behavior.

The effect of flight state parameters on the performance of photovoltaic modules in solar aircraft

Based on the power generation model of photovoltaic modules, the effects of flight speed, altitude, time and area in solar aircraft on the performance of photovoltaic modules have been studied. As the flight speed increases, the power generated by the module increases but tends to saturate. When the conversion efficiency of photovoltaic modules is improved, the required power of the solar aircraft and the power generated by the photovoltaic modules are balanced at a faster flight speed. The power generated by the modules increases with the flight altitude but tends to saturate due to the drop of air temperature and the surface temperature of the module. The higher the altitude, the smaller is the atmospheric density, and atmospheric permeability, and the greater is the solar radiation intensity, and thus the power generated by the module increases. The power generated by the components is the strongest at noon. Battery performance is the strongest in summer and the weakest in winter, as the module’s performance is mainly determined by the intensity of solar radiation. Finally, the energy distribution of solar aircraft and long-time space flight has been discussed. J. Bangladesh Acad. Sci. 45(1); 73-83: June 2021

Drone Application for Spraying Disinfection Liquid Fighting against the Covid-19 Pandemic—Examining Drone-Related Parameters Influencing Effectiveness

The Covid-19 pandemic has caused very serious problems almost to the whole world, so every opportunity must be considered to improve the situation. One such improvement strategy is decontamination carried out from the air. This technique can be considered for surface clearance of larger areas; hence, there is the need to investigate its effectiveness regarding the pandemic. There are many examples of the use of drones for disinfection to improve epidemic situations, but good practices, as well as factors influencing effectiveness, have not yet been identified. In the case of using drones for disinfection during a pandemic, the adapted use of agricultural drones is clear from reports. In this paper, the authors performed calculations with different values of flight speed (10 to 50 km/h), flight altitude (1 to 5 m), and flow rate (1 to 5 L/min) to determine the possible amount of disinfectant fluid per unit area. The results show that by changing the parameters, the amount of disinfectant per unit area can be given within quite wide limits (30–0.24 g/m2). Although the results raise many new questions, they can help to identify adequate flight parameters depending on different disinfectant liquids.