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Fabrics treated to repel water, superhydrophobic, and water and oil, superamphiphobic, have numerous industrial and consumer-level benefits. However, the liquid repellency decreases in the course of time. This is largely due to chemical or physical changes of the coating due to prolonged exposure to relatively harsh environments. To develop more durable fabric treatments for specific applications, it is necessary to measure the extent to which the treated fabrics retain their low-wettability after being subjected to controlled aggressive environmental conditions. In this study, plain weave fabrics made from polyester filaments and coated with silicone nanofilaments in-solution were exposed to aerodynamic icing conditions. The coated fabrics showed superhydrophobic behavior, or superamphiphobic for those that were fluorinated. The wettability of the fabrics was progressively evaluated by contact angle and roll-off-angle measurements. The coated fabrics were able to maintain their low-wettability characteristics after exposure to water droplet clouds at airspeeds up to 120 m/s, despite damage to the silicone nanofilaments, visible through scanning electron microscopy.

One may consider the application of remote sensing as a trade-off between the imaging platforms, sensors, and data gathering and processing techniques. This study addresses the potential of hyperspectral imaging using ultra-light aircraft for vegetation species mapping in an urban environment, exploring both the engineering and scientific aspects related to imaging platform design and image classification methods. An imaging system based on simultaneous use of Rikola frame format hyperspectral and Nikon D800E adopted colour infrared cameras installed onboard a Bekas X32 manned ultra-light aircraft is introduced. Two test imaging flight missions were conducted in July of 2015 and September of 2016 over a 4000 ha area in Kaunas City, Lithuania. Sixteen and 64 spectral bands in 2015 and 2016, respectively, in a spectral range of 500–900 nm were recorded with colour infrared images. Three research questions were explored assessing the identification of six deciduous tree species: (1) Pre-treatment of spectral features for classification, (2) testing five conventional machine learning classifiers, and (3) fusion of hyperspectral and colour infrared images. Classification performance was assessed by applying leave-one-out cross-validation at the individual crown level and using as a reference at least 100 field inventoried trees for each species. The best-performing classification algorithm—multilayer perceptron, using all spectral properties extracted from the hyperspectral images—resulted in a moderate classification accuracy. The overall classification accuracy was 63%, Cohen’s Kappa was 0.54, and the species-specific classification accuracies were in the range of 51–72%. Hyperspectral images resulted in significantly better tree species classification ability than the colour infrared images and simultaneous use of spectral properties extracted from hyperspectral and colour infrared images improved slightly the accuracy over the 2015 image. Even though classifications using hyperspectral data cubes of 64 bands resulted in relatively larger accuracies than with 16 bands, classification error matrices were not statistically different. Alternative imaging platforms (like an unmanned aerial vehicle and a Cessna 172 aircraft) and settings of the flights were discussed using simulated imaging projects assuming the same study area and field of application. Ultra-light aircraft-based hyperspectral and colour-infrared imaging was considered to be a technically and economically sound solution for urban green space inventories to facilitate tree mapping, characterization, and monitoring.

International audience; Few airborne aerosol research experiments have deployed N 2-Raman Lidar despite its capability to retrieve aerosol optical properties without ambiguity. Here, we show the high scientific potential of this instrument when used with specific flight plans. Our demonstration is based on (i) a field-experiment conducted in June 2015 in southern France, involving a N 2-Raman Lidar embedded on an ultra-light aircraft (ULA); and (ii) an appropriate algorithmic approach using two-level flight levels, aiming to solve the notorious instability of the airborne Lidar inversion for the retrieval of aerosol optical properties. The Lidar measurements include the determination of the aerosol extinction coefficient along~500 m horizontal line of sight, and this value is used as a reference to validate the proposed algorithm. The Lidar-derived vertical profiles obtained during the flights are used as an input in a Monte Carlo simulation in order to compute the error budget in terms of biases and standard deviations on the retrieved aerosol extinction coefficient profile, as well as the subsequent optical thickness. The influence of the Lidar ratio (i.e., between aerosol extinction and backscatter) on the error budget is further discussed. Finally, from this end-to-end modeling, an optimal N 2-Raman Lidar is proposed for airborne experiments, adapted to both small and large carriers.

This study focuses on the possibilities of using small format digital aerial images for the estimation of tree crown condition. The test area was located in the eastern part of Lithuania where Scots pine (Pinus sylvestris L.) trees prevail and was photographed using a Canon EOS-1DsMark II digital camera installed on-board a SkyArrow ultra-light aircraft. The camera lenses were adopted to capture images corresponding to conventional color-infrared photography. In addition, the test area was photographed using a large format digital frame aerial camera (Vexcel UltraCam D) installed on board a Rockwell Turbo Commander 690A high performance commuter aircraft. The ground sampling density of the images taken was around 9-10 cm. Crown defoliation was assessed in the field for more than 500 Scots pine trees located in 46 sample plots representing stands of trees that were either 65 years old or 170 years old. Spearman’s correlations coefficients were used to check for relationships between tree crown defoliation and image characteristics. The defoliation was also predicted using the non-parametric k-Nearest Neighbor method applied on data available from aerial images alone. The results were validated using the “Leave One Out” technique by comparing the obtained data with data from the field assessed defoliation rates. The prediction root mean square errors were calculated using data from the small format aerial images as being 11.5% for the younger trees, whereas those calculated using conventional aerial images were between 9.5 and 9.9%. The differences in predicted root mean square errors disappeared in the older stands and both methods produced errors of between 8.1 and 8.5%. Defoliation class was correctly predicted for approximately 84-88% of the older tree crowns and correctly for 75-85% of the younger tree crowns. These results showed that small format aerial images had the potential to predict defoliation in tree crowns and were comparable with results obtained using conventional aerial images. Their main advantage is that small format images are much cheaper to obtain than conventional images when the areas targeted are thousands of hectares in size.

Cilj ovog završnog rada je analizirati uzdužnu statičku stabilnost i ravnotežni let ultra-lakog zrakoplova za različite uvjete leta. Analizom se ostvaruje uvid u dio mogućnosti uporabe zrakoplova. Ultra-laki zrakoplov, koji se razmatra, predstavlja repliku zrakoplova Zlin XII. Nakon definirane geometrije, određeni su ukupni stacionarni koeficijenti normalne sile i momenta propinjanja čime je određen aerodinamički model. Određivanjem koeficijenata, omogućena je provjera statičke stabilnosti i analiza ravnotežnog leta. Osim toga, napravljena je procjena maksimalnog koeficijenta sile uzgona i maksimalnog napadnog kuta krila. The aim of this thesis is to analyze the longitudinal static stability and trimmed flight of ultra-light aircraft for different flight conditions. The analysis gives us better insight into some possibilities of the aircraft. Ultra-light aircraft, which is being considered, is a replica of the aircraft Zlin XII. After the geometry of the aircraft is defined, a total steady normal force and pitching moment coefficients are determined. This defined aerodynamic model for this work. Determined coefficients allows verification of static stability and trim analysis. In addition, the maximum lift coefficient and maximum angle of attack of wing is also determined.

International audience; Imaging system based on simultaneous use of Rikola hyperspectral and RGB/NIR cameras installed on a manned ultra-light aircraft is introduced in this study. Simultaneously acquired hyperspectral and color- infrared (CIR) images were tested for their potential to identify deciduous tree species and estimate tree health in Kaunas city, Lithuania. Six urban deciduous tree species were separated using tree crown level statistics, extracted from 16 visible-near infrared spectral band hyperspectral images, and discriminant analyses with an overall classification accuracy of 63.1 %. Classification accuracy increased by 3 percent when hyperspectral images were integrated with simultaneously acquired CIR images. The accuracy in identifying tree health using fused hyperspectral and CIR images, ranged from poor to moderate.

The present job is focused on a full composite ultra-light aircraft, and has the main goal of evaluating the existing margins for the improvement of the vehicle performance through a dedicated optimization of the aerodynamic and structural properties. For what concerns the aerodynamic properties of the entire aircraft, at first the attention has been focused on the airfoil chosen for the wings. Then the analysis of the complete wing and aircraft has been carried out. The preliminary investigation on the structural properties of the aircraft has been concerning an accurate evaluation of the operational external loads in order to obtain a confident estimation of the structural solicitation parameters and the identification of the most stressed aircraft structural parts.

In recent years, more and more light aircraft enter our daily life, from Agricultural applications, emergency rescue, flight experiment and training to Barriers to entry, light aircraft always have their own advantages. Thus, they have become more and more popular. However, in the process of GDP research about Flight Control System design for the Flying Crane, the author read a lot of literature about Flight Control System design, then noticed that the research in Flight Control System have apparently neglected to Low-cost vehicles. So it is necessary to do some study about Flight Control System for this kind of airplane. The study will more concern the control law design for ultra-light aircraft, the author hopes that with an ‘intelligence’ Flight Control System design, this kind of aircraft could sometimes perform flying tasks according to a prearranged flight path and without a pilot. As the Piper J-3 cub is very popular and the airframe data can be obtained more easily, it was selected as an objective aircraft for the control law design. Finally, a ¼ scale Piper J-3 cub model is selected and the aerodynamics coefficients are calculated by DATCOM and AVL. Based on the forces and moments acting on the aircraft, the trim equilibrium was calculated for getting proper dynamics coefficients for the selected flight conditions. With the aircraft aerodynamics coefficients, the aircraft dynamics characteristics and flying qualities are also analyzed. The model studied in this thesis cannot answer level one flying qualities in the longitudinal axis, which is required by MIL-F- 8785C. The stability augment system is designed to improve the flying qualities of the longitudinal axis. The work for autopilot design in this thesis includes five parts. First, the whole flight profile is designed to automatically control aircraft from takeoff to landing. Second, takeoff performance and guidance law is studied. Then, landing performance and trajectory is also investigated. After that, the control law design is decoupled into longitudinal axis and later-directional axis. Finally, simulation is executed to check the performance for the auto-controller.

We developed and installed a scientific payload on-board an ultra-light aircraft dedicated to ozone, nitrogen oxides and aerosol-scattering profilers to study the spatial distribution of pollution in the Chamonix and Maurienne valleys (French Alps). Meteorological parameters (temperature, pressure and relative humidity) and altimetry (GPS measurements) were recorded simultaneously. A synergy of measurements has been ensured with a ground mobile station equipped with a new lidar emitting at 532 nm. The experiment undertaken in January 2003 during the daytime allowed us to document, for the first time, the pollution level on horizontal and vertical scales during typical winter situations in the Alps valleys. Our results show a strong inversion of temperature up to about 150±50 m above the valley bottom, in the Chamonix valley, which traps the pollutants close to the snow-covered surface. Their concentrations are thus closely linked to the proximity of their sources and seem to have a local influence. In the Maurienne valley, with a bottom surface mostly free of snow, more efficient mixing due to convection is observed and a multi-layer structure between the planetary boundary layer and the free troposphere is detected on lidar vertical profiles. These lidar measurements allow a characterization of valley aerosols, with a backscatter to extinction ratio of not, vert, similar0.028 sr−1 very close to the value retrieved during the INDian Ocean EXperiment for a mixing of aerosols from biomass and fossil fuel burning.