We study the dynamics and the optimization of the shock deceleration supported by a payload when its airborne carrier impacts the ground. We build a nonlinear elastic model for a container prototype and an elastic suspension system for the payload. W
e model the dynamics of this system and extract information on maximum deceleration, energy transfer between the container and payload, and energy resonant damping. We designed the system and perform lab experiments for various terminal velocities and types of grounds (cement, grass, sand water, etc.). The results are compared with the theoretical model and results are commented, including predictions for deceleration at different types of ground impact. The results can be used for aerial delivery systems, splash-down of capsules, recoveries, weather balloons, coastal surveying systems, or the new introduced goal-line technology in sport competitions.
In this study we describe lab experiments on determining the above water reflectance Rrs coefficient, and the water attenuation coefficient Kd for fresh water. Different types of screens (totally absorbent, gray, etc.) were submerged in water (0-0.6
m) and illuminated from outside. The spectral density of the water leaving radiance was measured for different depths. The results were ran by a code which took into account the geometry of the incident irradiation, the geometry of the screen under water, and boundary conditions at the water surface provided by the radiation transfer theory. From the experimental data and our model we obtain the spectral distribution of the attenuation coefficient for fresh water and compared it with other data in literature. These experiments, performed in the Nonlinear Wave Lab at ERAU# represent just a preliminary calibration of the experimental protocol. More tests with water of different degrees of turbidity, and possibly wave filed at the water surface are in progress and will be presented in a forthcoming paper.
