Counting trees - methods of automatic analysis of photogrammetric data in forests of the continental region

The paper is devoted to the methods of automatic analysis of photogrammetric data in forests of the continental region. It also discusses how automatic tree counting can be used to manage forests. Experimental research was conducted to verify two methods: Faster R-CNN and Template Matching to automatically detecting tree objects in the continental region characterized by mixed forests with a large predominance of conifers. The research was done based on photogrammetric data taken in four areas belonging to forest districts subordinate to the Regional Directorate of State Forests in Zielona Góra. Data was collected from drones and small airplanes with a photogrammetric container. The results show that both methods can be used for analyzes in specific cases. Moreover, the level of Recall shows the advantage of Faster R-CNN methods for the photogrammetric data collected during the flights in various weather conditions.

Modeling and Control of a Single Rotor Composed of Two Fixed Wing Airplanes

This paper proposes a simple flying rotor prototype composed of two small airplanes attached to each other with a rigid rod so that they can rotate around themselves. The prototype is intended to perform hover flights with more autonomy than existing classic helicopters or quad-rotors. Given that the two airplanes can fly apart from each other, the induced flow which normally appears in rotorcrafts will be significantly reduced. The issue that is addressed in the paper is how this flying rotor prototype can be modeled and controlled. A model of the prototype is obtained by computing the kinetic and potential energies and applying the Euler Lagrange equations. Furthermore, in order to simplify the equations, it has been considered that the yaw angular displacement evolves much faster than the other variables. Furthermore a study is presented to virtually create a swashplate which is a central mechanism in helicopters. Such virtual swashplate is created by introducing a sinusoidal control on the airplanes’ elevators. The torque amplitude will be proportional to the sinusoidal amplitude and the direction will be determined by the phase of the sinusoidal. A simple nonlinear control algorithm is proposed and its performance is tested in numerical simulations.

Failure Modes of a Reticulated Dome in a Small Airplane Crash

Since the 9/11 incident, many engineering research works have been conducted on the impact resistance of large-span space structures. In the present study, a small airplane, Bombardier Challenger 850, was chosen as the test subject. An airplane crash on a single-layered Kiewitt-8 reticulated dome with span 60 m considering roof sheathing effect was simulated using ANSYS/LS-DYNA software. The principles of establishing the numerical model of small airplanes were determined. In addition, the impact styles of small airplane and impact positions on the dome were investigated. The failure modes of reticulated dome with roof sheathing due to small airplane crash were identified. Furthermore, the failure modes between reticulated domes with and without roof sheathing were compared and the effect of roof sheathing on the failure modes of reticulated dome under a small airplane crash was investigated.

The ASI Integrated Sounder-SAR System Operating in the UHF-VHF Bands: First Results of the 2018 Helicopter-Borne Morocco Desert Campaign

This work is aimed at showing the present capabilities and future potentialities of an imaging radar system that can be mounted onboard flexible aerial platforms, such as helicopters or small airplanes, and may operate in the UHF and VHF frequency bands as Sounder and as Synthetic Aperture Radar (SAR). More specifically, the Sounder operates at 165 MHz, whereas the SAR may operate either at 450 MHz or at 860 MHz. In the work, we present the first results relevant to a set of Sounder and SAR data collected by the radar during a helicopter-borne campaign conducted in 2018 over a desert area in Erfoud, Morocco, just after the conclusion of a system upgrading procedure. In particular, a first analysis of the focusing capabilities of the Sounder mode and of the polarimetric and interferometric capabilities of the SAR mode is conducted. The overall system, originally developed by CO.RI.S.T.A. according to a ASI funding set up in 2010, has been upgraded in the frame of a contract signed in 2015 between ASI and different private and public Italian Research Institutes and Universities, namely CO.RI.S.T.A., IREA-CNR, Politecnico di Milano and University of Trento.

The Fatigue Life of Cables in Aircraft Flight Control Systems

The cable flight control systems are commonly used for the control of small airplanes. In these systems, the cables are the only elements transmitting loads from the pilot to the control surfaces. During a flight the cables are moving through pulleys and are subjected to variable loads. A simple analysis of stress in the cable shows that the stress generated by the cyclical bending on the pulleys causes the fatigue of the wires. This phenomenon was noticed on a military aircraft of the M28 family during periodic maintenance inspection in 2007. The endurance tests of KSAN cables of the diameter equal to 3.5 mm and 1.8 mm were performed at the PZL MIELEC. The tests showed the limited fatigue life of the cables due to a progressive increase in the number of broken wires.