713 research outputs found
Sigma Point Kalman Filters for GPS Navigation with Integrity in Aviation
No full textThis paper presents an investigation into the benefits of Sigma Point Kalman Filters (SPKF) applied to GPSOnly estimation problem for highintegrity navigation in aviation applications. Navigation systems used for aircraft approach and landing must meet strict requirements for accuracy, integrity, availability and continuity. Modern GPS is capable of meeting the accuracy and availability requirements, however the integrity and continuity required for approach navigation mandate the use of additional sensors to meet the standards. Modern signal processing techniques can allow greater capability of existing systems, lowering the costs for all users of the system, particularly in the General Aviation sector. This work begins by comparing the raw estimation performance of the sigmapoint filter against established approaches of the Extended Kalman Filter (EKF) and snapshot Leastsquares (LSQ). The fault detection algorithms are then developed for the SPKF filters based on an approach used for highgrade navigation systems. It is hypothesised that since the SPKF can provide a more accurate estimate of the state covariance, then the fault detection scheme, including the integrity protection level, will be more reliable. Comparisons of the faultdetection performance against current techniques are presented. Finally, conclusions are drawn as to the overall benefits of the SPKF approach to navigation integrity. It is demonstrated that whilst the accuracy of the SPKF is not significantly different than the EKF or Least Squares approaches, the\ud
covariance estimation and resultant integrity protection level is reliable
A Vision Based Emergency Forced Landing System for an Autonomous UAV
No full textThis paper introduces the forced landing problem for UAVs and presents the machine-vision based approach taken for this research. The forced landing problem, is a new field of research for UAVs and this paper will show the preliminary analysis to date. The results are based on video data collected from a series of flight trials in a Cessna 172.\ud
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The aim of this research is to locate "safe" landing sites for UAV forced landings, from low quality aerial imagery. Output video image frames, will highlight the algorithm’s selected safe landing locations. The algorithms for the problem use image processing techniques and neural networks for the classification problem.\ud
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It should be noted that although the system is being designed primarily for the forced landing problem for UAVs, the research can also be applied to forced landings or glider applications for piloted aircraft
A Vision Based Forced Landing Site Selection\ud System for an Autonomous UAV
No full textThis paper presents a system overview of the UAV forced\ud
landing site selection system and the results to date. The\ud
forced landing problem is a new field of research for UAVs\ud
and this paper will show the machine vision approach taken\ud
to address this problem. The results are based on aerial\ud
imagery collected from a series of flight trials in a Cessna\ud
172.\ud
The aim of this research is to locate candidate landing sites\ud
for UAV forced landings, from aerial imagery. Output image\ud
frames highlight the algorithm’s selected safe landing\ud
locations. The algorithms for the problem use image\ud
processing techniques and neural networks for the\ud
classification problem.\ud
The system is capable of locating areas that are large enough\ud
to land in and that are free of obstacles 92.3% ± 2% (95%\ud
confidence) of the time. These areas identified are then\ud
further classified as to their surface type to a classification\ud
accuracy of 90% ± 3% (98% confidence).\ud
It should be noted that although the system is being designed\ud
primarily for the forced landing problem for UAVs, the\ud
research can also be applied to forced landings or glider\ud
applications for piloted aircraft
Pilotless aircraft: the horseless carriage of the twenty-first century?
No full textThis paper identifies recurring issues in the regulation of new technologies through an historical review of the risk management of automobiles in the 1800s. Parallels are drawn between the regulation of early automobiles and that of the regulation of Unmanned Aircraft Systems (UASs) today. It is found that many of the regulatory challenges facing UASs are analogous to those which faced the automobile industry more than a century and half ago and that the need for informed and objective decision making in policy development is reinforced. A systems engineering approach, based on general systems theory and decision-based design principles, is then proposed as a means for improving the objectivity, transparency and rationality in the risk management decision making process. An example risk management decision making scenario is given within the context of a small UAS operating over a populated area. The results obtained from this case study illustrate how even simple analysis can support the decision making process and highlights some of the potential challenges in the regulatory approach currently applied to UASs
A computationally intellgent framework for UAV forced landings
No full textA computationally intelligent framework has been developed for the forced landing problem for uninhabited airborne vehicles (UAVs). This framework locates landing areas within an image that are of the appropriate geometrical size and free of obstacles. The surface-type of the candidate landing areas are classified into categories such as grass, trees and water. The classification results are combined with other information such as, the spatial relationships between candidate areas, the presence of moving objects (for example cars and people) and the objects in surrounding the areas, to nominate candidate UAV forced landing sites.\ud
A discussion is presented that shows that a type-2 fuzzy-based approach is expected to be useful in resolving data-set uncertainties allowing a reliable UAV forced landing site recommendation to be made. Examples of data-set uncertainties include the surface type classification and the models of motion of various objects.\ud
Results are presented showing the successful location of appropriate candidate UAV landing sites. A success rate of 90% has been achieved using a neural network classification approach and based on the testing of 500 images. These results are based on actual flight imagery collected from a Cessna 172 flight over Brisbane, Australia
sj-docx-1-anp-10.1177_00048674231175618 – Supplemental material for Predictors of individual mental health and psychological resilience after Australia’s 2019–2020 bushfires
No full textSupplemental material, sj-docx-1-anp-10.1177_00048674231175618 for Predictors of individual mental health and psychological resilience after Australia’s 2019–2020 bushfires by Emily Macleod, Timothy Heffernan, Lisa-Marie Greenwood, Iain Walker, Jo Lane, Samantha K Stanley, Olivia Evans, Alison L Calear, Tegan Cruwys, Bruce K Christensen, Tim Kurz, Emily Lancsar, Julia Reynolds, Rachael Rodney Harris and Stewart Sutherland in Australian & New Zealand Journal of Psychiatry</p
Status of anadromous salmonids in Oregon coastal basins
No full textThomas E. Nickelson, Jay W. Nicholas, Alan M. McGie, Robert B. Lindsay, Daniel L. Bottom (Research and Development Section, Oregon Department of Fish and Wildlife), and Rodney J. Kaiser, Steven E. Jacobs (Ocean Salmon Management, Oregon Department of Fish and Wildlife).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references (pages 71-81).Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Definition of airworthiness categories for civil Unmanned Aircraft Systems (UAS)
No full textThis paper introduces a novel strategy for the specification of airworthiness certification categories for civil unmanned aircraft systems (UAS).\ud
The risk-based approach acknowledges the fundamental differences between the risk paradigms of manned and unmanned aviation. The proposed airworthiness certification matrix provides a systematic and objective structure for regulating the airworthiness of a diverse range of UAS types and operations.\ud
An approach for specifying UAS type categories is then discussed. An example of the approach, which includes the novel application of data-clustering algorithms, is presented to illustrate the discussion
Single- and Multi-carrier Quadrature Amplitude Modulation: Principles and Applications for Personal Communications, WATM and Broadcasting: 2nd
No full textSingle- and Multi-carrier Quadrature Amplitude Modulation Principles and Applications for Personal Communications, WLANs and Broadcasting L. Hanzo Department of Electronics and Computer Science, University of Southampton, UK W. Webb Motorola, Arlington Heights, USA formerly at Multiple Access Communications Ltd, Southampton, UK T. Keller Ubinetics, Cambridge Technology Centre, Melbourn, UK formerly at Department of Electronics and Computer Science, University of Southampton, UK Motivated by the rapid evolution of wireless communication systems, this expanded second edition provides an overview of most major single- and multi-carrier Quadrature Amplitude Modulation (QAM) techniques commencing with simple QAM schemes for the uninitiated through to complex, rapidly-evolving areas, such as arrangements for wide-band mobile channels. Targeted at the more advanced reader, the multi-carrier modulation based second half of the book presents a research-orientated outlook using a variety of novel QAM-based arrangements. * Features six new chapters dealing with the complexities of multi-carrier modulation which has found applications ranging from Wireless Local Area Networks (WLAN) to Digital Video Broadcasting (DVB) * Provides a rudimentary introduction for readers requiring a background in the field of modulation and radio wave propagation * Discusses classic QAM transmission issues relevant to Gaussian channels * Examines QAM-based transmissions over mobile radio channels * Incorporates QAM-related orthogonal techniques, considers the spectral efficiency of QAM in cellular frequency re-use structures and presents a QAM-based speech communications system design study * Introduces Orthogonal Frequency Division Multiplexing (OFDM) over both Gaussian and wideband fading channels By providing an all-encompassing self-contained treatment of single- and multi- carrier QAM based communications, a wide range of readers including senior undergraduate and postgraduate students, practising engineers and researchers alike will all find the coverage of this book attractive
Figure 1 in Taxonomy And Phylogenetics Of The Peromyscus Maniculatus Species Group
No full textFigure 1. Map of the general distributions of species in the P. maniculatus group as discussed and recognized herein. Peomyscus sejugis is restricted to Isla Santa Cruz and Isla San Diego in the Gulf of California and is not figured. Numbers in parentheses refer to the DNA clades as designated by Dragoo et al. (2006), and cross hatching indicates distributional overlap of P. melanotis and P. labecula. The general distributions of species were determined by plotting the geographically marginal specimens reported in the following papers: Bowers et al. (1973), Allard and Greenbaum (1988), Hogan et al. (1993), Wike (1998), Zheng et al. (2003), Lucid and Cook (2004), Dragoo et al. (2006), Walker et al. (2006), Lucid and Cook (2007), Gering et al. (2009), Yang and Kenagy (2011), Domingues et al. (2012), Kalkvik et al. (2012), Natarajan et al. (2015), Greenbaum et al. (2017), Kingsley et al. (2017), Sawyer et al. (2017), and Kalkvik et al. (2018).Published as part of Greenbaum, Ira F., Honeycutt, Rodney L. & Chirhart, Scott E., 2019, Taxonomy And Phylogenetics Of The Peromyscus Maniculatus Species Group, pp. 559-575 in Special Publications of the Museum of Texas Tech University 71 on page 563, DOI: 10.5281/zenodo.722112
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