34,611 research outputs found
Eliciting expert judgement for the probability of AUV loss in contrasting operational environments
Get PDFEach time an autonomous underwater vehicle (AUV)
is used in the sea there is a non-zero probability of
loss. Quantifying probability of loss is not an exact
science; therefore much depends on the fault history
of the vehicle, the operational environment and the
complex relationships between the consequences of
faults or incidents and the environment. While this
problem may be stated in scientific terms, in practice,
there is no solution through scientific means alone.
This is an example of ‘trans-science’. We suggest that
an approach based on the formal process of eliciting
expert judgement may be an effective means of
approaching this problem, as the process has been
used successfully for other trans-scientific questions.
The paper provides an introduction to the process of
eliciting expert judgement, outlines four exemplar
environments: coastal, open water, under sea ice and
under shelf ice, and gives a worked example of one
expert’s judgement on the probability of loss in the
four environments arising from a real fault with the
Autosub1 AUV. Using the fault history of the
Autosub3 AUV, included in the Annex, we ask
experts from among UUST attendees (and others) to
take part in this expert judgement elicitation. Based
on the results of this elicitation we aim to publish a
paper in the peer-reviewed literature
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Theoretical Loss and Gambling Intensity (Revisited): A Response to Braverman et al. (2013)
No full textIn this paper, we provide a brief response to Braverman and colleagues’ (2013) critique of our ‘Theoretical Loss’ metric as a measure of monetary gambling intensity (Auer & Griffiths, 2013; Auer, Schneeberger & Griffiths, 2012). We argue that ‘gambling intensity’ and ‘gambling involvement’ are essentially the same construct as descriptors of monetary gambling activity. Additionally, we acknowledge that playing duration (i.e., the amount of time – as opposed to money – actually spent gambling) is clearly another important indicator of gambling involvement – something that we have consistently noted in our previous studies including our empirical studies on gambling using behavioural tracking data. Braverman and colleagues claim that the concept of Theoretical Loss is nullified when statistical analysis focuses solely on one game type as the house edge is constant across all games. In fact, they state, the correlation between total amount wagered and Theoretical Loss is perfect. Unfortunately, this is incorrect. To disprove the claim made, we demonstrate that in sports betting (i.e., a single game type), the amount wagered does not reflect monetary gambling involvement using actual payout percentage data (based on 52,500 independent bets provided to us by an online European bookmaker). After reviewing the arguments presented by Braverman and colleagues, we are still of the view that when it comes to purely monetary measures of ‘gambling intensity’, the Theoretical Loss metric is a more robust and accurate measure than other financial proxy measures such as ‘amount wagered’ (i.e., bet size) as a measure of what players are prepared to financially risk while gambling
The calibration of two acoustic current meters developed at the Christian Michelsen Institute, Norway
No full textContributions to the Science of Environmental Impact Assessment: Three Papers on the Arctic Cisco (Coregonus autumnalis) of Northern Alaska
Get PDFEditor's Introduction -- D. W. Norton; An Assessment of the Colville River Delta Stock of Arctic Cisco--Migrants from Canada? -- B. J. Gallaway, W. B. Griffiths, P. C. Craig, W. J. Gazey, and J. W. Helmericks; Temperature Preference of Juvenile Arctic Cisco (Coregonus autumnalis) From the Alaskan Beaufort Sea -- R. G. Fechhelm, W. H. Neill, and B. J. Gallaway; Modeling Movements and Distribution of Arctic Cisco (Coregonus autumnalis) Relative to Temperature-Salinity Regimes of the Beaufort Sea Near the Waterflood Causeway, Prudhoe Bay, Alaska. -- W. H. Neill, R. G. Fechhelm, B. J. Gallaway, J. D. Bryan, and S. W. Anderson; Notice to Author
RRS James Cook Cruise JC009T, 01 May - 11 May 2007. Trials of the Isis Remotely Operated Vehicle
No full textRisk Analysis for Autonomous Underwater Vehicle Operations in Extreme Environments
Get PDFAutonomous underwater vehicles (AUVs) are used increasingly to explore hazardous marine environments. Risk assessment for such complex systems is based on subjective judgment and expert knowledge as much as on hard statistics. Here, we describe the use of a risk management process tailored to AUV operations, the implementation of which requires the elicitation of expert judgment. We conducted a formal judgment elicitation process where eight world experts in AUV design and operation were asked to assign a probability of AUV loss given the emergence of each fault or incident from the vehicle's life history of 63 faults and incidents. After discussing methods of aggregation and analysis, we show how the aggregated risk estimates obtained from the expert judgments were used to create a risk model. To estimate AUV survival with mission distance, we adopted a statistical survival function based on the nonparametric Kaplan-Meier estimator. We present theoretical formulations for the estimator, its variance, and confidence limits. We also present a numerical example where the approach is applied to estimate the probability that the Autosub3 AUV would survive a set of missions under Pine Island Glacier, Antarctica in January–March 2009
Analysis of causation of loss of communication with marine autonomous systems: a probability tree approach
Get PDFThe last decade has seen the eagerly anticipated introduction of marine autonomous systems as a pragmatic tool for ocean observation. However, outstanding reliability problems means that these vehicles are not yet fulfilling their true potential. Of the classes of problems, loss of communication with a marine autonomous system is both fundamental and difficult to diagnose. In our view, this is due to two reasons: first in many cases users are not technologists and secondly if a vehicle is lost the task of diagnosing the root cause is subject to epistemic uncertainty that users are often reluctant to quantify in a formal manner. As a result users may accept the first hypothesis considered as the main root cause for loss of communication. We show that this approach can result in an increased unreliability of marine autonomous systems through failure to ascertain and then address the true root causes. Consequently, we propose a probability tree approach to help diagnose root cause(s) for loss of communication with a marine autonomous system (MAS). The model was developed based on the results of two detailed investigations and a body of failure data collected from 205 undersea glider operations
Conulinus randalanai Griffiths & Herbert 2013, sp. n.
No full textConulinus randalanai sp. n. Fig. 10 Etymology: Named for Roger Randalana, on-site manager of the Tsingy Beanka reserve and participant in many malacological expeditions throughout Madagascar. Diagnosis: Shell bulimiform, whorls relatively elongate, body whorl comprising approx. 66% of total shell height; spire profile cyrtoconoid; columella reflected, umbilicus narrow; sculptured by microscopic axial riblets and even finer spiral threads; lustreless, mauve-brown, paler apically. Description: Shell: Elongate-bulimiform, thin; body whorl comprising approx. 66 % of total shell height; spire profile cyrtoconoid, suture not strongly indented; whorls weakly convex, base a little more strongly so, periphery rounded; umbilicus reduced to a narrow tube-like channel by reflected upper portion of columella lip. Protoconch of approx. 1¼ whorls, smooth. Teleoconch of a further 4¾–5 whorls; appearing smooth, but microsculptured by numerous, very fine, close-set axial riblets, and even finer microscopic spiral threads; axial riblets becoming less regular with growth and resembling fine, uneven growthlines on last adult whorl, spiral sculpture persisting throughout and extending on to base. Aperture elongate-ovate; somewhat oblique to vertical axis of shell; peristome incomplete, simple and thin; no subterminal thickening evident inside outer lip; upper part of columella reflected and compressed against preceding whorl such that its edge is narrow (pleat-like in some specimens) and the umbilicus restricted to a very narrow, tube-like channel. Shell somewhat lustreless rather than glossy; predominantly mauve-brown in the freshest specimens, with some axial variations in intensity particularly on middle spire whorls; paler pinkish brown to fawn apically. Dimensions: Holotype, height 16.9 mm, max. diameter 8.5 mm; largest specimen, height 17.5 mm. Holotype: MADAGASCAR: Central W Madagascar, ca 60 km E of Maintirano, E of Belitsaka, E part of Tsingy Beanka, 18.06145°S 44.52595°E, ca 450 m, in leaf-litter and tsingy slots in comparatively lush tall dry deciduous/evergreen forest on south-facing hill, 2.x.2006, O. Griffiths, R. Randalana, D. Herbert & L. Davis, st’n 12/06 (AMS C.469591). Paratypes: St’n R 02/10 (NMSA L8469 /T2897, 1 specimen; AMS C.469584, 4 specimens; MNHN IM-2010-20069, 1 specimen). Additional locality data: Tsingy Beanka: st’ns 03/10, 11/10. Distribution: Evidently a narrow-range endemic; known only from the Tsingy Beanka. Habitat: Fresh dead shells have been found in tall, relatively lush dry deciduous and evergreen forest. No living specimens known. Remarks:The only comparable species known from Madagascar is C. rufoniger (Reeve, 1849), but that species differs in having more rounded whorls, a less elongate shape and a darker, chestnut brown colour (Fig. 7D, E). It also lacks spiral sculpture, and has a wider umbilicus and a thickened white varix inside the outer lip at maturity. C. rufoniger has been mostly recorded from north-eastern Madagascar (Fischer-Piette et al. 1994), but we can also confirm its presence at Antsingimavo (st’ns 04/06, 06/06), Tsingy Beanka (st’ns 01/09, 02/09, 09/09) and in the Tsingy de Bemaraha (Manombolo River). In the absence of anatomical data, our referral of this species to Conulinus is tentative. In its shape and spiral microsculpture, C. randalanai also resembles some species of Rachis Albers, 1850, but it lacks the colour pattern of dark spots and/or spiral bands commonly seen in species of that genus. Indeed, the referral of C. rufoniger to Conulinus also requires confirmation.Published as part of Griffiths, O. L. & Herbert, D. G., 2013, New species of land snails (Mollusca: Gastropoda) from two isolated karst formations in central western Madagascar: Tsingy Beanka and Antsingimavo, with additional notes on other regional endemics, pp. 1-48 in African Invertebrates 54 (1) on pages 15-16, DOI: 10.5733/afin.054.0101, http://zenodo.org/record/767010
Some Observations on the Construction of Space in the Prose of W. G. Sebald
No full textPierwodruk: „Białostockie Studia Literaturoznawcze” 2016, nr 8.This essay discusses the relationship between how space is constructed in the works of W. G. Sebald, and a fundamental characteristic of his texts, namely their hybridity. The author focuses, in particular, on the function of photography in Sebald’s narrations. Photographs, though themselves iconographic signs with strong referentiality, do not eliminate a strong textualization of space in Sebald’s works.Katedra Teorii Literatury, Uniwersytet Łódzki814115
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