2,953 research outputs found
Standards and Testing Agency annual report and financial statements 2012-2013: (for the year ended 31 March 2013)
Enabling power: Education Act 1996, s. 537A (4) (5) (6). Issued: 29.05.2013. Made: 20.05.2013. Laid: 29.05.2013. Coming into force: 28.06.2013. Effect: S.I. 2009/1563 amended. Territorial extent and classification: E. General
Measurements of underwater piling noise during nearshore windfarm construction in the UK potential impact on marine mammals in compliance with German UBA limit
Offshore construction work, such as pile and conductor driving, can potentially cause acoustic disturbance to marine mammals, such as cetaceans (whales, dolphins and por-poises), the odontocetes (toothed cetaceans) of which rely on the underwater sound field for spatial orientation, navigation, prey capture, communication, and predator avoidance. Disturbance ranges from behavioural changes, masking of communication signals, and temporary or even permanent hearing loss. There is currently no specific legal noise threshold in UK waters, but the Marine Management Organisation (MMO) has stipulated the requirement for noise monitoring during pile-driving operations when some windfarms are constructed. Measurements presented in this paper were taken during nearshore pile driving in the UK from a support vessel located 750 m from each pile (wind-turbine foun-dation). Results were compared with a threshold issued by the German Federal Environ-ment Agency (UBA). Noise level beyond the measurement location was predicted using a numerical model. Comparing results with the Southall criteria (Southall, B. L., et al., Ma-rine Mammal Noise Exposure Criteria: Initial Scientific Recommendations. Aquatic Mam-mals, 33 (4), 2007), the Joint Nature Conservation Committee (JNCC) 500 m exclusion zone offered protection for most of marine mammals during pile driving events in this particular case.
Keywords: Underwater piling noise, wind-farm, marine mammals, UBA limi
Model-Based Control Using Koopman Operators
This paper explores the application of Koopman operator theory to the control
of robotic systems. The operator is introduced as a method to generate
data-driven models that have utility for model-based control methods. We then
motivate the use of the Koopman operator towards augmenting model-based
control. Specifically, we illustrate how the operator can be used to obtain a
linearizable data-driven model for an unknown dynamical process that is useful
for model-based control synthesis. Simulated results show that with increasing
complexity in the choice of the basis functions, a closed-loop controller is
able to invert and stabilize a cart- and VTOL-pendulum systems. Furthermore,
the specification of the basis function are shown to be of importance when
generating a Koopman operator for specific robotic systems. Experimental
results with the Sphero SPRK robot explore the utility of the Koopman operator
in a reduced state representation setting where increased complexity in the
basis function improve open- and closed-loop controller performance in various
terrains, including sand.Comment: 8 page
Does action disrupt Multiple Object Tracking (MOT)?
While the relationship between action and focused attention has been well-studied, less is known about the ability to divide attention while acting. In the current paper we explore this issue using the multiple object tracking (MOT) paradigm (Pylyshyn & Storm, 1988). We asked whether planning and executing a display-relevant action during tracking would substantially affect the ability track and later identify targets. In all trials the primary task was to track 4 targets among a set of 8 identical objects. Several times during each trial, one object, selected at random, briefly changed colour. In the baseline MOT trials, these changes were ignored. During active trials, each changed object had to be quickly touched. On a given trial, changed objects were either from the tracking set or were selected at random from all 8 objects. Although there was a small dual-task cost, the need to act did not substantially impair tracking under either touch condition.peer-reviewe
- …