Background: Spontaneous magnetic alignment (SMA), in which animals position their body axis in fixed alignments relative to magnetic field lines, has been shown in several classes of vertebrates and invertebrates. Although these responses appear to be widespread, the functional significance and sensory mechanism(s) underlying SMA remain unclear. An intriguing example comes from observations of wild red foxes (Vulpes vulpes) that show a ~fourfold increase in hunting success when predatory 'mousing' attacks are directed toward magnetic north-northeast. This form of SMA is proposed to receive input from a photoreceptor-based magnetoreception mechanism perceived as a 'visual pattern' and used as a targeting system to increase the accuracy of mousing attempts targeting hidden prey. However, similar to previous observational studies of magnetic orientation in vertebrates, direct evidence for the use of magnetic cues, and field-based experiments designed to characterize the biophysical mechanisms of SMA are lacking. Here, we develop a new approach for studies of SMA using triaxial accelerometer and magnetometer bio-loggers attached to semidomesticated red foxes.Results: Accelerometer data were recorded from 415 ground-truth events of three behaviors exhibited by an adult red fox. A 5-nearest neighbor classifier was developed for behavioral analysis and performed with an accuracy of 95.7% across all three behaviors. To evaluate the generalizability of the classifier, data from a second fox were tested yielding an accuracy of 66.7%, suggesting the classifier can extract behaviors across multiple foxes. A similar classification approach was used to identify the fox's magnetic alignment using two 8-way classifiers with differing underlying assumptions to distinguish magnetic headings in eight equally spaced 45° sectors. The magnetic heading classifiers performed with 90.0 and 74.2% accuracy, suggesting a realistic performance range for a classifier based on an independent set of training events equal in size to our sample. Conclusions:We report the development of 'magnetic ethograms' in which the behavior and magnetic alignment of foxes can be accurately extracted from raw sensor data. These techniques provide the basis for future studies of SMA where direct observation is not necessary and may allow for more sophisticated experimental designs aimed to characterize the sensory mechanisms mediating SMA behavior.

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This paper addresses the investigation into the feasibility of the use of precision guided airdrop as a means to deliver cargo to naval vessels at sea. In this context, precision guided airdrop means delivering unmanned cargo packages that, once dropped from an aircraft at high altitude, have the capability to guide themselves to a precise landing point by controlling an aerodynamic decelerator (parafoil or parachute) to which the cargo package is attached. The paper describes the problem of replenishment of naval vessels at sea and describes the benefits that the application of precision airdrop might provide. Improved accuracy of aerial delivery systems is the major focus of analysis, and how the application of model predictive control has potential to achieve the necessary improvements in accuracy that would make shipboard landings possible. A simple example is developed of a model predictive control algorithm adapted to track a target landing area that is moving with constant velocity. Additional techniques are also surveyed, as well as other potential applications of precision airdrop to maritime operations.

This paper presents a self-contained aerial payload/sensor delivery system Blizzard and discusses its potential applications.

This paper examines some of the challenges that must be overcome if future aerial delivery systems are to have the capability to land on the flight deck of a ship underway. The unique aspects of trajectory planning for landing on a ship's flight deck are first examined, followed by formulation of the position estimation problem for a moving target. Some preliminary investigations into characterizing the wind over a moving landing platform at sea are then described. Finally, experimental results are presented for testing of a small prototype autonomous parafoil with a simple moving target on land. Nomenclature ADS