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The modeling and simulation of electrical power systems has become a primary design tool for the synthesis of aerospace power systems with hybrid AC/DC distribution. Although in the past the use of extensive time domain simulations using detailed models has been favored, the need to study stability and associated phenomena in this type of power systems-having a high penetration of power electronics loads-has transformed the modeling requirements for aerospace applications. This paper explores different modeling aspects required to study both small-signal and large-signal stability in these systems, providing insight into the development of key system component models-variable frequency generators, line-commutated converters, PWM motor drives and constant power loads, as well as the theoretical foundations based on the Generalized Nyquist Criterion and the Lyapunov Direct and Indirect Methods to fully assess the stability conditions of these power systems.

This paper describes an experimental framework to track a meteorological balloon at low altitudes using unmanned aerial vehicles (UAVs). The purpose of the experiment is to simulate the trajectories of plant pathogen spores using a buoyancy controlled weather balloon. In the described framework the balloon is instrumented with an onboard telemetry unit to broadcast its GPS coordinates and other flight and meteorological data. The UAV's circular flight pattern is centered on the current position of the balloon, where the position coordinates are shared over a wireless network. The principal advantage of using the weather balloon is to increase the likelihood of detecting airborne pathogens by sampling inside the spore plume. The apparatus enables the UAVs to sample larger distances away from the source than previously possible.