Abstract: A method of identifying operational modes experienced by a user during a jump from an aircraft may comprise estimating a user altitude and a user descent rate, based on a set of navigation state data vectors. The method may further comprise determining that the user is ready to transition from a flight mode to a descent mode when the user altitude is above a jump altitude threshold, and a variation of the user altitude is below a predetermined altitude variation threshold. After determining that the user is ready to transition from the flight mode to the descent mode, the method further comprises determining that the user has transitioned from a flight mode to a descent mode when a user ground speed is below a ground speed threshold, and one or both of (i) a GNSS position error estimate, and (ii) the user descent rate estimate, indicates a jump signature.

Abstract: A method of identifying operational modes experienced by a user during a jump from an aircraft may comprise estimating a user altitude and a user descent rate, based on a set of navigation state data vectors. The method may further comprise determining that the user is ready to transition from a flight mode to a descent mode when the user altitude is above a jump altitude threshold, and a variation of the user altitude is below a predetermined altitude variation threshold. After determining that the user is ready to transition from the flight mode to the descent mode, the method further comprises determining that the user has transitioned from a flight mode to a descent mode when a user ground speed is below a ground speed threshold, and one or both of (i) a GNSS position error estimate, and (ii) the user descent rate estimate, indicates a jump signature.

Abstract: One of two coils of approximately the same diameter, forming the primary and secondary coils of a transformer for tube welding or other induction heating equipment, is mounted for movement relative to the other, preferably about a pivotal axis parallel to the axes of the coils, to enable its axis to be shifted towards and away from the axis of the other coil and the coils are so arranged that loops or turns of each coil, which are connected together in series or parallel, can pass between the loops or turns of the other coil to facilitate changing the coupling factor and thus adjusting the power delivered to the heating coil.