1,559 research outputs found
Quantifying Operational Constraints of Low-Latency Telerobotics for Planetary Surface Operations
NASA's SLS and Orion crew vehicle will launch humans to cislunar space to
begin the new era of space exploration. NASA plans to use the Orion crew
vehicle to transport humans between Earth and cislunar space where there will
be a stationed habitat known as the Deep Space Gateway (DSG). The proximity to
the lunar surface allows for direct communication between the DSG and surface
assets, which enables low-latency telerobotic exploration. The operational
constraints for telerobotics must be fully explored on Earth before being
utilized on space exploration missions. We identified two constraints on space
exploration using low-latency surface telerobotics and attempts to quantify
these constraints. A constraint associated with low-latency surface
telerobotics is the bandwidth available between the orbiting command station
and the ground assets. The bandwidth available will vary during operation. As a
result, it is critical to quantify the operational video conditions required
for effective exploration. We designed an experiment to quantify the threshold
frame rate required for effective exploration. The experiment simulated
geological exploration via low-latency surface telerobotics using a COTS rover
in a lunar analog environment. The results from this experiment indicate that
humans should operate above a threshold frame rate of 5 frames per second. In a
separate, but similar experiment, we introduced a 2.6 second delay in the video
system. This delay recreated the latency conditions present when operating
rovers on the lunar farside from an Earth-based command station. This time
delay was compared to low-latency conditions for teleoperation at the DSG
(0.4 seconds). The results from this experiment show a 150% increase in
exploration time when the latency is increased to 2.6 seconds. This indicates
that such a delay significantly complicates real-time exploration strategies.Comment: 10 pages, 8 figures, Proceedings of the IEEE Aerospace Conference,
Big Sky, MT. arXiv admin note: text overlap with arXiv:1706.0375
Consolidity: Mystery of inner property of systems uncovered
AbstractThis paper uncovers the mystery of consolidity, an inner property of systems that was amazingly hidden. Consolidity also reveals the secrecy of why strong stable and highly controllable systems are not invulnerable of falling and collapsing. Consolidity is measured by its Consolidity Index, defined as the ratio of overall changes of output parameters over combined changes of input and system parameters, all operating in fully fuzzy environment. Under this notion, systems are classified into consolidated, quasi-consolidated, neutrally consolidated, unconsolidated, quasi-unconsolidated and mixed types. The strategy for the implementation of consolidity is elaborated for both natural and man-made existing systems as well as the new developed ones. An important critique arises that the by-product consolidity of natural or built-as-usual system could lead to trapping such systems into a completely undesired unconsolidity. This suggests that the ample number of conventional techniques that do not take system consolidity into account should gradually be changed, and adjusted with improved consolidity-based techniques. Four Golden Rules are highlighted for handling system consolidity, and applied to several illustrative case studies. These case studies cover the consolidity analysis of the Drug Concentration problem, Predator-Prey Population problem, Spread of Infectious Disease problem, AIDS Epidemic problem and Arm Race model. It is demonstrated that consolidity changes are contrary (opposite in sign) to changes of both stability and controllability. This is a very significant result showing that our present practice of stressing on building strong stable and highly controllable systems could have already jeopardized the consolidity behavior of an ample family of existing real life systems. It is strongly recommended that the four Golden Rules of consolidity should be enforced as future strict regulations of systems modeling, analysis, design and building of different disciplines of sciences. It can be stated that with the mystery of consolidity uncovered, the door is now wide open towards the launching of a new generation of systems with superior consolidity in various sciences and disciplines. Examples of these disciplines are basic sciences, evolutionary systems, engineering, astronautics, astronomy, biology, ecology, medicine, pharmacology, economics, finance, commerce, political and management sciences, humanities, social sciences, literature, psychology, philosophy, mass communication, and education
Otolith chemoscape analysis in whiting links fishing grounds to nursery areas
Understanding life stage connectivity is essential to define appropriate spatial scales for fisheries management and develop effective strategies to reduce undersized bycatch. Despite many studies of population structure and connectivity in marine fish, most management units do not reflect biological populations and protection is rarely given to juvenile sources of the fished stock. Direct, quantitative estimates which link specific fishing grounds to the nursery areas which produced the caught fish are essential to meet these objectives. Here we develop a continuous-surface otolith microchemistry approach to geolocate whiting (Merlangius merlangus) and infer life stage connectivity across the west coast of the UK. We show substantial connectivity across existing stock boundaries and identify the importance of the Firth of Clyde nursery area. This approach offers fisheries managers the ability to account for the benefits of improved fishing yields derived from spatial protection while minimising revenue loss
Predictive GAM seabed maps can account for defined and fuzzy boundaries to improve accuracy in a scottish sea loch seascape
Marine seabed mapping is an important element in marine spatial and conservation planning. Recent large scale mapping programmes have greatly increased our knowledge of the seafloor, yet at finer resolutions, large gaps remain. Loch Eriboll, Scotland, is an area of conservation interest with a diverse marine environment supporting habitats and species of conservation importance. Here we test and present strategies for a predictive seabed substrata map for Loch Eriboll using drop down Stereo Baited Remote Underwater Video (SBRUV) imagery collected as part of systematic underwater survey of the Loch. A total of 216 SBRUV deployments were made across the study site in depths of 3 m–117 m, with six seabed classes identified using an adaptation of the EUNIS (European Nature Information System) hierarchical habitat classification scheme. Four statistical learning approaches were tested, we found, Generalised Additive Models (GAMs) provided the optimal balance between over- and underfitted predictions. We demonstrate the creation of a predictive substratum habitat map covering 63 km2 of seabed which predicts the probability of presence and relative proportion of substratum types. Our method enables naturally occurring edges between habitat patches to be described well, increasing the accuracy of mapping habitat boundaries when compared to categorical approaches. The predictions allow for both defined boundaries such as those between sand and rock and fuzzy boundaries seen among fine mixed sediments to exist in the same model structure. We demonstrate that SBRUV imagery can be used to generate cost effective, fine scale predictive substrata maps that can inform marine planning. The modelling procedure presented has the potential for a wide adoption by marine stakeholders and could be used to establish baselines for long term monitoring of benthic habitats and further research such as animal distribution and movement work which require detailed benthic maps
A holonomy characterisation of Fefferman spaces
We prove that Fefferman spaces, associated to non--degenerate CR structures
of hypersurface type, are characterised, up to local conformal isometry, by the
existence of a parallel orthogonal complex structure on the standard tractor
bundle. This condition can be equivalently expressed in terms of conformal
holonomy. Extracting from this picture the essential consequences at the level
of tensor bundles yields an improved, conformally invariant analogue of
Sparling's characterisation of Fefferman spaces.Comment: AMSLaTeX, 15 page
A new model study species: high accuracy of discrimination between individual freckled hawkfish (Paracirrhites forsteri) using natural markings
Variations between distinct natural markings of freckled hawkfish (Paracirrhites forsteri) could allow in situ identification of individuals from underwater photography. Receiver operating characteristic analysis was used to assess the ability of the Interactive Individual Identification System (I3S) software to assist in discriminating between images of P. forsteri individuals. This study's results show the high discriminant ability of I3S to differentiate between unlike individuals and identify images of the same individual. The ability to use automatic computer-aided assistance in the study of this species will enable future research to explore behaviour and movements of individuals in the wild
Scalp Hematoma Characteristics Associated with Intracranial Injury in Pediatric Minor Head Injury
Objectives Minor head trauma accounts for a significant proportion of pediatric emergency department (ED) visits. In children younger than 24 months, scalp hematomas are thought to be associated with the presence of intracranial injury (ICI). We investigated which scalp hematoma characteristics were associated with increased odds of ICI in children less than 17 years who presented to the ED following minor head injury and whether an underlying linear skull fracture may explain this relationship. Methods This was a secondary analysis of 3,866 patients enrolled in the Canadian Assessment of Tomography of Childhood Head Injury (CATCH) study. Information about scalp hematoma presence (yes/no), location (frontal, temporal/parietal, occipital), and size (small and localized, large and boggy) was collected by emergency physicians using a structured data collection form. ICI was defined as the presence of an acute brain lesion on computed tomography. Logistic regression analyses were adjusted for age, sex, dangerous injury mechanism, irritability on examination, suspected open or depressed skull fracture, and clinical signs of basal skull fracture. Results ICI was present in 159 (4.1%) patients. The presence of a scalp hematoma (n = 1,189) in any location was associated with significantly greater odds of ICI (odds ratio [OR] = 4.4, 95% confidence interval [CI] = 3.06 to 6.02), particularly for those located in temporal/parietal (OR = 6.0, 95% CI = 3.9 to 9.3) and occipital regions (OR = 5.6, 95% CI = 3.5 to 8.9). Both small and localized and large and boggy hematomas were significantly associated with ICI, although larger hematomas conferred larger odds (OR = 9.9, 95% CI = 6.3 to 15.5). Although the presence of a scalp hematoma was associated with greater odds of ICI in all age groups, odds were greatest in children aged 0 to 6 months (OR = 13.5, 95% CI = 1.5 to 119.3). Linear skull fractures were present in 156 (4.0%) patients. Of the 111 patients with scalp hematoma and ICI, 57 (51%) patients had a linear skull fracture and 54 (49%) did not. The association between scalp hematoma and ICI attenuated but remained significant after excluding patients with linear skull fracture (OR = 3.3, 95% CI = 2.1 to 5.1). Conclusions Large and boggy and nonfrontal scalp hematomas had the strongest association with the presence of ICI in this large pediatric cohort. Although children 0 to 6 months of age were at highest odds, the presence of a scalp hematoma also independently increased the odds of ICI in older children and adolescents. The presence of a linear skull fracture only partially explained this relation, indicating that ruling out a skull fracture beneath a hematoma does not obviate the risk of intracranial pathology
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