scholarly journals An investigation into the impact of unmanned aerial vehicles on soundscape perception in urban and rural environments

2021 ◽  
Vol 263 (6) ◽  
pp. 577-588
Author(s):  
Rory Nicholls ◽  
Antonio Torija Martinez
Keyword(s):  
Background Noise ◽  
Measurement Procedure ◽  
Limiting Factors ◽  
Response Measurement ◽  
Sound Recordings ◽  
Community Noise ◽  
Rural Environments ◽  
Future Extension ◽  
Aerial Vehicle ◽  
The Impact

It is predicted that urban air mobility, including the use of small to medium sized unmanned aerial vehicle (UAV) delivery systems, will be introduced into cities across the globe within the next 15 years. It is known, however, that noise is one of the main limiting factors for the wider adoption of these vehicles. Neither the metrics nor the methods used for conventional aircraft seem to be optimal for this novel source of noise. This research will aid in developing suitable psychoacoustic methodologies and metrics, specifically designed to quantify community noise impact of these vehicles. This paper describes a psychoacoustic experiment used to gather participant responses to UAV sound recordings, both isolated and with typical background noise in a diversity of soundscapes. Results from this psychoacoustic experiment will be used to correlate perceptions of UAV noise with objective sound quality metrics, and build new regression relationships that could describe the impact of a given UAV on the perception of soundscape environments. Future extension to the research may include evaluating the differences in psychoacoustic responses when introducing more accurate reproduction methods, such as virtual reality systems, and how these could be incorporated into a standardised human response measurement procedure.

AMBIENT NOISE: PROBLEM AND STUDY IN THE FRAMEWORK OF UAV AEROACOUSTICS

Akustika ◽  
2021 ◽  
pp. 16-21
Author(s):  
Petr Moshkov
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Background Noise ◽  
Ambient Noise ◽  
Spectral Characteristics ◽  
Wind Noise ◽  
Community Noise ◽  
Noise Masker ◽  
Aerial Vehicle

The role of ambient noise in the problem of community noise of propeller-driven unmanned aerial vehicle is considered. The results of the author's measurements of the spectral characteristics of the background in open terrain, in the mountains, near the sea and the highway are presented. An expression is proposed for calculating the spectrum of background noise in open terrain (wind noise). It is shown that the ambient noise can be an effective noise masker of propeller-driven UAV in the low and medium frequencies.

Energy absorbed ability and damage analysis for honeycomb sandwich material of bio-inspired micro aerial vehicle under low velocity impact

2020 ◽  
pp. 095440622097542
Author(s):  
Jianxun Du ◽  
Peng Hao ◽  
Mabao Liu ◽  
Rui Xue ◽  
Lin’an Li
Keyword(s):  
Honeycomb Structure ◽  
Low Velocity Impact ◽  
Parameter Study ◽  
Low Velocity ◽  
Micro Aerial Vehicle ◽  
Thin Walled Structures ◽  
Wide Range ◽  
Aerial Vehicle ◽  
Thin Walled ◽  
The Impact

Because of the advantages of light weight, small size, and good maneuverability, the bio-inspired micro aerial vehicle has a wide range of application prospects and development potential in military and civil areas, and has become one of the research hotspots in the future aviation field. The beetle’s elytra possess high strength and provide the protection of the abdomen while being functional to guarantee its flight performance. In this study, the internal microstructure of beetle’s elytra was observed by scanning electron microscope (SEM), and a variety of bionic thin-walled structures were proposed and modelled. The energy absorption characteristics and protective performance of different configurations of thin-walled structures with hollow columns under impact loading was analyzed by finite element method. The parameter study was carried out to show the influence of the velocity of impactor, the impact angle of the impactor and the wall thickness of honeycomb structure. This study provides an important inspiration for the design of the protective structure of the micro aerial vehicle.

A Novel Design of Landing Gear Oleo Strut Damper Using MR Fluid for Aircraft and UAV’s

2012 ◽  
Vol 225 ◽  
pp. 275-280
Author(s):  
Chandra B. Asthana ◽  
Rama B. Bhat
Keyword(s):  
Shock Absorber ◽  
Fluid Viscosity ◽  
Simulation Approach ◽  
Body Frame ◽  
Mr Fluid ◽  
Orifice Area ◽  
Aerial Vehicle ◽  
Impact Kinetic Energy ◽  
The Impact ◽  
Novel Design

Most landing gears used in aircraft employ very efficient oleo-pneumatic dampers to absorb and dissipate the impact kinetic energy of the aircraft body frame. A single-acting shock absorber is most commonly used in the oleo strut that has a metering pin extending through the orifice, which can vary the orifice area upon compression and extension of the strut. This variation is adjusted by shaping the metering pin so that the strut load is fairly constant under dynamic loading. In this paper, it is proposed to further change the damping coefficient as a function of time in order to achieve a semi-active control of the aircraft vibrations during landing by using Magnetorheological (MR) fluid in the Oleo. With the metering pin designed for a nominal flight condition, further variation in the fluid viscosity would help achieve the optimal performance in off-nominal flight conditions. A simulation approach is employed to show the effect of different profiles for viscosity variation in the MR fluid. The utility of such a damper can be very well exploited to include different criteria such as the landing distance after touchdown. This type of system can be used also in Unmanned Aerial Vehicle (UAV) application where the focus of design may be to accomplish the task without the consideration of passenger comfort.

Blind Identification of Impact Forces From Multiple Remote Vibratory Measurements

2000 ◽  
Author(s):  
J. Antunes ◽  
P. Izquierdo ◽  
M. Paulino
Keyword(s):  
Explicit Knowledge ◽  
Transfer Functions ◽  
Dynamical Behavior ◽  
Practical Interest ◽  
Operating Conditions ◽  
Blind Identification ◽  
Minimum Entropy ◽  
Response Measurement ◽  
Identification Techniques ◽  
The Impact

Abstract Structures and mechanical components are often subjected to impulsive forces. There is a need for identification techniques which enable monitoring of such loads under operating conditions. For safety reasons and convenience, force identification must often be based on response motions sensed at accessible locations, remote from the impact points. In our previous work we presented techniques for the experimental identification of both isolated impacts and complex rattling forces on a beam, generated at a single and also at several impacting supports. The system dynamical behavior was modeled using traveling flexural beam waves. Although successful, these techniques obviously assume a good understanding of the system dynamic parameters. This is not always the case, a fact that highlights the practical interest of blind identification techniques. This relatively recent field, connected with higher-order statistics, avoids any explicit knowledge of the system transfer functions or impulse responses. Our previous work, based on a single response measurement, is extended in this paper to include several simultaneous responses. We develop a multi-trace version of Wiggins minimum-entropy blind deconvolution algorithm. From numerical simulations and experiments, it is shown that the robustness to noise contamination is increased by using multiple response data. These results suggest that blind identification techniques will prove very useful in practical situations.

Impact of N-Shaped Wing Morphing on Solar-Powered Aircraft

2020 ◽  
pp. 1-12
Author(s):  
Mostafa E. El-Salamony ◽  
Mohamed A. Aziz
Keyword(s):  
Solar Energy ◽  
Lift Coefficient ◽  
Morphing Wing ◽  
Aerial Vehicles ◽  
Aircraft Performance ◽  
Aerial Vehicle ◽  
Solar Powered ◽  
Two Parameters ◽  
Wing Morphing ◽  
The Impact

Generally, unmanned aerial vehicles and micro aerial vehicles depend on batteries or conventional fuel as a source of energy. These sources of energy have limited flight time, relatively high cost, and also a certain level of pollutants. Solar energy applied to aerial vehicles is an excellent alternative way to overcome other sources of energy’s disadvantage. This study aimed to design a solar-powered aerial vehicle to achieve continuous flight on Earth. The efficiency of the solar system is related to the absorbed sun rays. The concept of an anti-symmetric N-shaped morphing wing is a good idea to increase the collected solar energy during the daily sun path. But this comes with the penalty of side forces and moments due to the anti-symmetry of the wing. This paper introduces a study for two parameters that strongly affect the aerodynamics of the N-shaped morphing wing; the dihedral part angle and the dihedral part length. The impact of the dihedral angle decreases the lift coefficient and increases the drag coefficient. The impact of the morphing wing on the aircraft performance is also considered.

scholarly journals Activity density of carabid beetles along an urbanisation gradient

2020 ◽  
Vol 66 (Suppl.) ◽  
pp. 21-36
Author(s):  
Simone Fattorini ◽  
Cristina Mantoni ◽  
Davide Bergamaschi ◽  
Lorenzo Fortini ◽  
Francisco J. Sánchez ◽  
...  
Keyword(s):  
Intermediate Disturbance Hypothesis ◽  
Urban Environments ◽  
Carabid Beetles ◽  
City Centre ◽  
Intermediate Disturbance ◽  
Rural Environments ◽  
Activity Density ◽  
Urban Rural ◽  
The Impact ◽  
The City

Several works have investigated the impact of urbanisation on carabid activity density using urban-rural gradients. Such works compared activity density recorded from green spaces located in different parts of a city and assigned to categories of increasing urban intensity, which poses two problems: (1) since the gradient is divided into categories, it is impossible to model continuous variations in biotic responses, and (2) sites representative of different urbanisation levels are not true segments of the same ecological continuum. To surpass these problems, we modelled variations in carabid activity density along an urban-rural transect within a single green space extending from the city centre of Rome to rural environments. Carabids were sampled by pitfall traps from sites distributed along the entire gradient. We used breakpoint regressions to model how (1) carabid activity density, (2) carabids/beetles ratio, (3) carabids/insects ratio and (3) carabids/arthropods ratio varied along the gradient. As already observed for various organisms in urban environments, we found that activity density of carabids and their contribution to the abundance of beetles, insects and arthropods, peaked in the middle of the gradient. This supports the intermediate disturbance hypothesis, according to which moderate urbanisation may favour diversity by increasing habitat heterogeneity.

scholarly journals Automated Bale Mapping Using Machine Learning and Photogrammetry

2021 ◽  
Vol 13 (22) ◽  
pp. 4675
Author(s):  
William Yamada ◽  
Wei Zhao ◽  
Matthew Digman
Keyword(s):  
Lower Cost ◽  
Mean Squared Error ◽  
Spatial Clustering ◽  
Mean Average Precision ◽  
Average Precision ◽  
Data Set ◽  
Map Projection ◽  
Squared Error ◽  
Aerial Vehicle ◽  
The Impact

An automatic method of obtaining geographic coordinates of bales using monovision un-crewed aerial vehicle imagery was developed utilizing a data set of 300 images with a 20-megapixel resolution containing a total of 783 labeled bales of corn stover and soybean stubble. The relative performance of image processing with Otsu’s segmentation, you only look once version three (YOLOv3), and region-based convolutional neural networks was assessed. As a result, the best option in terms of accuracy and speed was determined to be YOLOv3, with 80% precision, 99% recall, 89% F1 score, 97% mean average precision, and a 0.38 s inference time. Next, the impact of using lower-cost cameras was evaluated by reducing image quality to one megapixel. The lower-resolution images resulted in decreased performance, with 79% precision, 97% recall, 88% F1 score, 96% mean average precision, and 0.40 s inference time. Finally, the output of the YOLOv3 trained model, density-based spatial clustering, photogrammetry, and map projection were utilized to predict the geocoordinates of the bales with a root mean squared error of 2.41 m.

scholarly journals Development and Analysis of New NLFM Waveform for Achieving Sidelobe Reduction and Narrowing of Main lobe Width

2021 ◽  
Vol 9 (7) ◽  
pp. 885-889
Keyword(s):  
Doppler Effect ◽  
Background Noise ◽  
Sampling Rate ◽  
Ambiguity Function ◽  
Main Lobe ◽  
The Doppler Effect ◽  
The Impact ◽  
Lobe Width

Aimed at narrowing main lobe width and reduced sidelobe values, we developed three new NLFM chirp waveforms. The ambiguity function and the impact of sampling rate and compression ratios of these waveforms are analyzed. Their performance is examined against the doppler effect and background noise. One of the three designed NLFM chirp waveforms is useful in applications requiring side lobes of -50 dB and narrow main lobe width. The new waveform could achieve reduced sidelobes and narrow main lobe width compared to LFM and other NLFM waveforms

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