Detecting execution failures using learned action models

Planners reason with abstracted models of the behaviours they use to construct plans. When plans are turned into the instructions that drive an executive, the real behaviours interacting with the unpredictable uncertainties of the environment can lead to failure. One of the challenges for intelligent autonomy is to recognise when the actual execution of a behaviour has diverged so far from the expected behaviour that it can be considered to be a failure. In this paper we present an approach by which a trace of the execution of a behaviour is monitored by tracking its most likely explanation through a learned model of how the behaviour is normally executed. In this way, possible failures are identified as deviations from common patterns of the execution of the behaviour. We perform an experiment in which we inject errors into the behaviour of a robot performing a particular task, and explore how well a learned model of the task can detect where these errors occur

An Experimental Investigation Of The Aerodynamic Losses For An Incident Tolerant Low Pressure Turbine Blade Over Moderate To Low Reynolds Numbers At Engine Representative Mach Numbers

In the interest of reducing airport congestion in the near future, researchers at NASA Glenn Research Facility have envisioned a new civilian transport aircraft which takes off vertically and cruises horizontally at Mach 0.5 using tilt-rotor technology. The engine under development consists of a four stage low pressure (LP) turbine. Many challenges are presented as the engine transitions from 100% shaft speed at takeoff to 54% shaft speed at cruise. The blading in this engine must be designed to optimize fuel efficiency, especially at cruise. The flow conditions in the LP turbine will change significantly from a Reynolds number of about 500,000 with a nearly tenfold drop to 50,000. The low Reynolds number flow enhances the susceptibility of separation and introduces more aerodynamic losses which will act to reduce the overall efficiency of the blade design. The vastly changing shaft speeds will induce a large variation in the flow\u27s incidence angle of about 60°. The changing Reynolds number and incidence angle increases the complexity of the flow and will have a significant effect on transition and separation phenomena along the blading. Testing for this blade design was conducted in the University of North Dakota\u27s high speed low Reynolds number facility. This facility is configured in a closed-circuit arrangement and allows for steady-state high speed testing at pressures well below atmospheric. The facility was configured to accommodate a six blade five full passage linear cascade to experimentally acquire aerodynamic data concerning the inlet boundary layers, blade load distributions and total pressure losses over a wide range of Reynolds numbers and incidence angles. The Reynolds numbers under investigation were based off exit conditions and true chord and range incrementally from 50,000 to 568,000. Eight discrete inlet nozzles were fabricated for this study based of the inlet angle measured from the axial direction: -17°, -12°, -2.6°, 8°, 18°, 28°, 34.2° and 40°. These inlet angles correspond to a range of incidence angles from -51.2° to 5.8°. In addition to the Reynolds number and incidence angle effect, the effects of low and moderate turbulence intensity were also investigated. The aerodynamic losses were measured via a five-hole stinger type cone probe. The key component of this study were the mass averaged total pressure loss buckets which encompassed the range of Reynolds numbers and incidence angles under low and moderate turbulence conditions

A Safeguards Design Strategy for Domestic Nuclear Materials Processing Facilities.

The outdated and oversized nuclear manufacturing complex within the United States requires its transformation into a smaller, safe, and secure enterprise. Health and safety risks, environmental concerns, and the end of the Cold War have all contributed to this necessity. The events of September 11, 2001, emphasized the protection requirements for nuclear materials within the U.S. as well as abroad. Current Nuclear Safeguards regulations contain minimal prescriptive requirements relating to the design of new production facilities. Project management and engineering design guides require that design documents contain specific and measureable statements relating to systems requirements. The systems engineering process evaluates alternatives for an effective and integrated solution during project design. A Safeguards Design Strategy for domestic nuclear materials processing facilities based upon a core framework of safeguards regulatory programmatic elements that also use the prescriptive requirements and similar goals of safety, health, and physical security regulations is proposed and justifiable

Geometry, evolution and scaling of fault relay zones in 3D using detailed observations from outcrops and 3D seismic data

A new surface attribute was developed during the course of the thesis, which enables fault-related deformation – specifically, the apparent dip of mapped horizons measured in a direction perpendicular to the average strike of a fault array (here termed “fault-normal rotation”, or “FNR”) – to be quantitatively analysed around imaged faults. The new utility can be applied to any 3D surface and was used to analyse centimetre-scale to kilometre-scale fault-arrays, interpreted from laser scan point clouds, digital elevation models, and 3D seismic datasets. In all studied examples, faults are surrounded by volumes of fault-related deformation that have variable widths, and which can consist of faults, fractures and continuous bed rotations (i.e. monoclines). The vertical component of displacement calculated from the areas of fault-related deformation on each horizon act to “fill-in” apparently missing displacements observed in fault throw profiles at fault overlaps. This result shows that complex 3D patterns of fault-related strain commonly develop during the geometrically coherent growth of a single fault-array. However, if the component of continuous deformation was not added to the throw profile, the fault-array could have been misinterpreted as a series of isolated fault segments with coincidental overlaps. The FNR attribute allows the detailed, quantitative analysis of fault linkage geometries. It is shown that overlapping fault tip lines in relay zones can link simultaneously at multiple points, which results in a segmented branch line. Fault linkage in relay zones is shown to control the amount of rotation accommodated by relay ramps on individual horizons, with open relay ramps having accommodated by larger rotations than breached relay ramps in the same relay zone. Displacements are therefore communicated between horizons in order to maintain strain compatibility within the relay zone. This result is used to predict fault linkage in the subsurface, along slip-aligned branch lines, from the along-strike displacement distributions at the earth’s surface. Relay zone aspect ratios (AR; overlap/separation) are documented to follow power-law scaling relationships over nine orders of magnitude with a mean AR of 4.2. Approximately one order of magnitude scatter in both separation and overlap exists at all scales. Up to half of this scatter can be attributed to the spread of measurements recorded from individual relay zones, which relates to the evolution of relay zone geometries as the displacements on the bounding faults increase. Mean relay AR is primarily controlled by the interactions between the stress field, of a nearby fault, and overlapping fault tips, rather than by the host rock lithology. At the Kilve and Lamberton study areas, mean ARs are 8.60 and 8.64 respectively, which are much higher than the global mean, 4.2. Scale-dependent factors, such as mechanical layering and heterogeneities at the fault tips are present at these locations, which modify how faults interact and produce relatively large overlap lengths for a given separation distance. Despite the modification to standard fault interaction models, these high AR relay zones are all geometrically coherent