ORCID Profile
0000-0002-7491-7386
Current Organisations
UNSW Sydney
,
Trillium Technologies
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Publisher: American Astronomical Society
Date: 12-2021
Abstract: The Radio Arc is a system of organized nonthermal filaments (NTFs) located within the Galactic center (GC) region of the Milky Way. Recent observations of the Radio Arc NTFs revealed a magnetic field that alternates between being parallel and rotated with respect to the orientation of the filaments. This pattern is in stark contrast to the predominantly parallel magnetic field orientations observed in other GC NTFs. To help elucidate the origin of this pattern, we analyze spectro-polarimetric data of the Radio Arc NTFs using an Australian Telescope Compact Array data set covering the continuous frequency range from ∼4 to 11 GHz at a spectral resolution of 2 MHz. We fit depolarization models to the spectral polarization data to characterize Faraday effects along the line of sight. We assess whether structures local to the Radio Arc NTFs may contribute to the unusual magnetic field orientation. External Faraday effects are identified as the most likely origin of the rotation observed for the Radio Arc NTFs however, internal Faraday effects are also found to be likely in regions of parallel magnetic field. The increased likelihood of internal Faraday effects in parallel magnetic field regions may be attributed to the effects of structures local to the GC. One such structure could be the Radio Shell local to the Radio Arc NTFs. Future studies are needed to determine whether this alternating magnetic field pattern is present in other multi-stranded NTFs, or is a unique property resulting from the complex interstellar region local to the Radio Arc NTFs.
Publisher: Frontiers Media SA
Date: 20-10-2022
DOI: 10.3389/FMARS.2022.981897
Abstract: Over the last five years remotely piloted drones have become the tool of choice to spot potentially dangerous sharks in New South Wales, Australia. They have proven to be a more effective, accessible and cheaper solution compared to crewed aircraft. However, the ability to reliably detect and identify marine fauna is closely tied to pilot skill, experience and level of fatigue. Modern computer vision technology offers the possibility of improving detection reliability and even automating the surveillance process in the future. In this work we investigate the ability of commodity deep learning algorithms to detect marine objects in video footage from drones, with a focus on distinguishing between shark species. This study was enabled by the large archive of video footage gathered during the NSW Department of Primary Industries Drone Trials since 2016. We used this data to train two neural networks, based on the ResNet-50 and MobileNet V1 architectures, to detect and identify ten classes of marine object in 1080p resolution video footage. Both networks are capable of reliably detecting dangerous sharks: 80% accuracy for RetinaNet-50 and 78% for MobileNet V1 when tested on a challenging external dataset, which compares well to human observers. The object detection models correctly detect and localise most objects, produce few false-positive detections and can successfully distinguish between species of marine fauna in good conditions. We find that shallower network architectures, like MobileNet V1, tend to perform slightly worse on smaller objects, so care is needed when selecting a network to match deployment needs. We show that inherent biases in the training set have the largest effect on reliability. Some of these biases can be mitigated by pre-processing the data prior to training, however, this requires a large store of high resolution images that supports augmentation. A key finding is that models need to be carefully tuned for new locations and water conditions. Finally, we built an Android mobile application to run inference on real-time streaming video and demonstrated a working prototype during fields trials run in partnership with Surf Life Saving NSW.
Publisher: EDP Sciences
Date: 13-05-2009
Publisher: Springer Science and Business Media LLC
Date: 27-06-2023
DOI: 10.1038/S41598-023-34436-W
Abstract: Cognitive cloud computing in space (3CS) describes a new frontier of space innovation powered by Artificial Intelligence, enabling an explosion of new applications in observing our planet and enabling deep space exploration. In this framework, machine learning (ML) payloads—isolated software capable of extracting high level information from onboard sensors—are key to accomplish this vision. In this work we demonstrate, in a satellite deployed in orbit, a ML payload called ‘WorldFloods’ that is able to send compressed flood maps from sensed images. In particular, we perform a set of experiments to: (1) compare different segmentation models on different processing variables critical for onboard deployment, (2) show that we can produce, onboard, vectorised polygons delineating the detected flood water from a full Sentinel-2 tile, (3) retrain the model with few images of the onboard sensor downlinked to Earth and (4) demonstrate that this new model can be uplinked to the satellite and run on new images acquired by its camera. Overall our work demonstrates that ML-based models deployed in orbit can be updated if new information is available, paving the way for agile integration of onboard and onground processing and “on the fly” continuous learning.
Publisher: Oxford University Press (OUP)
Date: 12-2012
DOI: 10.1093/MNRAS/STS350
Publisher: Oxford University Press (OUP)
Date: 19-07-2018
Publisher: Cambridge University Press (CUP)
Date: 05-2005
Publisher: EDP Sciences
Date: 17-07-2008
Publisher: IOP Publishing
Date: 09-2012
DOI: 10.1086/668058
Publisher: American Astronomical Society
Date: 20-02-2013
Publisher: American Astronomical Society
Date: 24-04-2015
Publisher: Oxford University Press (OUP)
Date: 23-02-2016
DOI: 10.1093/MNRAS/STW359
Publisher: Oxford University Press (OUP)
Date: 24-01-2017
DOI: 10.1093/MNRAS/STX206
Publisher: Cambridge University Press (CUP)
Date: 08-2016
DOI: 10.1017/S1743921316007638
Abstract: Massive stars are some of the most important objects in the Universe, shaping the evolution of galaxies, creating chemical elements, and hence shaping the evolution of the Universe. However, the processes by which they form, and how they shape their environment during their birth processes, are not well understood. We are using NH 3 data from the “The H 2 O Southern Galactic Plane Survey” (HOPS) to define the positions of dense cores/clumps of gas in the southern Galactic plane that are likely to form stars. We did a comparative study with different methods for finding clumps and found Fellwalker to be the best for this dataset. We detected ~ 500 clumps with mean kinetic temperature ~ 20 K and virial mass ~ 680 solar masses.
Publisher: Cambridge University Press (CUP)
Date: 2006
DOI: 10.1071/AS06003
Abstract: We report on the detection of HCO + and 12 CO emission in the rotational transition J = 1–0 in the vicinity of the shock front at the southern border of the supernova remnant RCW 103, where previous infrared observations suggest an interaction with a molecular cloud. The observations were carried out with the Australian Millimeter Radiotelescope at Mopra. We observed a depletion of HCO + behind the supernova shock front. In addition, we studied the interstellar medium over an extended region towards RCW 103 based on archival λ 21 cm Hı line observations from the Australia Telescope Compact Array (ATCA) and the Parkes Telescope. No atomic gas was observed in emission in coincidence with the molecular feature. This absence was interpreted in terms of self-absorption processes.
Publisher: Cambridge University Press (CUP)
Date: 2005
DOI: 10.1071/AS04068
Publisher: Oxford University Press (OUP)
Date: 03-2006
Publisher: Oxford University Press (OUP)
Date: 27-10-2018
Publisher: MDPI AG
Date: 21-01-2021
Abstract: Over the past decade, drones have become a popular tool for wildlife management and research. Drones have shown significant value for animals that were often difficult or dangerous to study using traditional survey methods. In the past five years drone technology has become commonplace for shark research with their use above, and more recently, below the water helping to minimise knowledge gaps about these cryptic species. Drones have enhanced our understanding of shark behaviour and are critically important tools, not only due to the importance and conservation of the animals in the ecosystem, but to also help minimise dangerous encounters with humans. To provide some guidance for their future use in relation to sharks, this review provides an overview of how drones are currently used with critical context for shark monitoring. We show how drones have been used to fill knowledge gaps around fundamental shark behaviours or movements, social interactions, and predation across multiple species and scenarios. We further detail the advancement in technology across sensors, automation, and artificial intelligence that are improving our abilities in data collection and analysis and opening opportunities for shark-related beach safety. An investigation of the shark-based research potential for underwater drones (ROV/AUV) is also provided. Finally, this review provides baseline observations that have been pioneered for shark research and recommendations for how drones might be used to enhance our knowledge in the future.
Publisher: Cambridge University Press (CUP)
Date: 03-2007
DOI: 10.1017/S1743921307012677
Abstract: Methanol maser emission has proven to be an excellent signpost of regions undergoing massive star formation (MSF). To investigate their role as an evolutionary tracer, we have recently completed a large observing program with the ATCA to derive the dynamical and physical properties of molecular/ionised gas towards a s le of MSF regions traced by 6.7GHz methanol maser emission. We find that the molecular gas in many of these regions breaks up into multiple sub-clumps which we separate into groups based on their association with/without methanol maser and cm continuum emission. The temperature and dynamic state of the molecular gas is markedly different between the groups. Based on these differences, we attempt to assess the evolutionary state of the cores in the groups and thus investigate the role of class II methanol masers as a tracer of MSF.
Publisher: Oxford University Press (OUP)
Date: 15-05-2017
Publisher: Oxford University Press (OUP)
Date: 21-03-2009
Publisher: Oxford University Press (OUP)
Date: 29-07-2014
Publisher: Oxford University Press (OUP)
Date: 18-06-2014
DOI: 10.1093/MNRAS/STU989
Publisher: Oxford University Press (OUP)
Date: 19-08-2013
Publisher: Oxford University Press (OUP)
Date: 22-02-2017
DOI: 10.1093/MNRAS/STX338
Publisher: Oxford University Press (OUP)
Date: 05-02-2018
DOI: 10.1093/MNRAS/STY269
Publisher: EDP Sciences
Date: 2011
DOI: 10.1051/EAS/1152021
Publisher: Springer Science and Business Media LLC
Date: 2013
DOI: 10.1038/NATURE11734
Abstract: The nucleus of the Milky Way is known to harbour regions of intense star formation activity as well as a supermassive black hole. Recent observations have revealed regions of γ-ray emission reaching far above and below the Galactic Centre (relative to the Galactic plane), the so-called 'Fermi bubbles'. It is uncertain whether these were generated by nuclear star formation or by quasar-like outbursts of the central black hole and no information on the structures' magnetic field has been reported. Here we report observations of two giant, linearly polarized radio lobes, containing three ridge-like substructures, emanating from the Galactic Centre. The lobes each extend about 60 degrees in the Galactic bulge, closely corresponding to the Fermi bubbles, and are permeated by strong magnetic fields of up to 15 microgauss. We conclude that the radio lobes originate in a biconical, star-formation-driven (rather than black-hole-driven) outflow from the Galaxy's central 200 parsecs that transports a huge amount of magnetic energy, about 10(55) ergs, into the Galactic halo. The ridges wind around this outflow and, we suggest, constitute a 'phonographic' record of nuclear star formation activity over at least ten million years.
Publisher: Oxford University Press (OUP)
Date: 02-2005
Publisher: Oxford University Press (OUP)
Date: 08-2007
Publisher: Oxford University Press (OUP)
Date: 07-02-2014
DOI: 10.1093/MNRAS/STU032
Publisher: Sissa Medialab
Date: 02-2018
DOI: 10.22323/1.277.0015
Publisher: American Astronomical Society
Date: 12-2017
Publisher: Oxford University Press (OUP)
Date: 24-05-2017
Publisher: EDP Sciences
Date: 16-06-2008
Publisher: Cambridge University Press (CUP)
Date: 05-2005
Publisher: EDP Sciences
Date: 09-07-2009
Publisher: Oxford University Press (OUP)
Date: 21-04-2006
Publisher: Oxford University Press (OUP)
Date: 21-12-2013
DOI: 10.1093/MNRAS/STS376
Publisher: EDP Sciences
Date: 2005
Publisher: Oxford University Press (OUP)
Date: 02-03-2011
Publisher: CRC Press
Date: 18-06-2014
DOI: 10.1201/B17046
Publisher: Cambridge University Press (CUP)
Date: 2012
DOI: 10.1071/AS11062
Abstract: The H 2 O Southern Galactic P lane S urvey (HOPS) has observed 100 deg 2 of the Galactic plane, using the Mopra radio telescope to search for emission from multiple spectral lines in the 12-mm band (19.5–27.5 GHz). Perhaps the most important of these spectral lines is the 22.2-GHz water-maser transition. We describe the methods used to identify water-maser candidates and subsequent confirmation of the sources. Our methods involve a simple determination of likely candidates by searching peak emission maps, utilising the intrinsic nature of water-maser emission, spatially unresolved and spectrally narrow-lined. We estimate completeness limits and compare our method with results from the duch source finder. We find that the two methods perform similarly. We conclude that the similarity in performance is due to the intrinsic limitation of the noise characteristics of the data. The advantages of our method are that it is slightly more efficient in eliminating spurious detections and is simple to implement. The disadvantage is that it is a manual method of finding sources and so is not practical on datasets much larger than HOPS, or for datasets with extended emission that needs to be characterised. We outline a two-stage method for the most efficient means of finding masers, using duch .
Publisher: EDP Sciences
Date: 15-10-2008
Publisher: Oxford University Press (OUP)
Date: 03-12-2013
Publisher: Oxford University Press (OUP)
Date: 14-08-2017
Publisher: EDP Sciences
Date: 03-2016
Publisher: Elsevier BV
Date: 05-2021
Publisher: Cambridge University Press (CUP)
Date: 11-2009
DOI: 10.1017/S1743921310011592
Abstract: The CORNISH (Co-Ordinated Radio ‘N’ Infrared Survey for High-mass star formation) project is the radio continuum part of a series of multi-wavelength surveys of the Galactic Plane that focus on the northern GLIMPSE-I region (10° l °, | b | 1°) observed by the SPITZER satellite in the mid-infrared (Churchwell et al . 2009). CORNISH has delivered a complementary 5 GHz arcsecond resolution, radio-continuum survey to address key questions in high-mass star formation as well as many other areas of astrophysics.
Publisher: Oxford University Press (OUP)
Date: 12-2008
Publisher: American Astronomical Society
Date: 31-01-2012
Publisher: Oxford University Press (OUP)
Date: 11-2007
Publisher: Oxford University Press (OUP)
Date: 27-02-2015
DOI: 10.1093/MNRAS/STV178
Publisher: Zenodo
Date: 2016
DOI: 10.5281/ZENODO.60636
No related grants have been discovered for Cormac Purcell.