Effect of Chaotic Nature on IPHICLUS and NEARCTIC Flapping MAV Wings in Lift Generation using Welch Power Spectral

The application of bio-mimetic in Micro Aerial Vehicles (MAV) is a developing field and has enormous applications in the aviation industry. In this work, experimental investigation of the insect like MAV having flapping wing is discussed. The iphiclus-egensis-aile flexible wing and the nearctic-ceratopogonidae flexible wing were chosen for this study. Values of the coefficient of lift for the unsteady aerodynamics were converted to normalized frequency domain using Welch power spectral density method at various flapping frequencies and Reynolds number. The wing tip vortices were captured using laser visualization technique and further the images were processed using MATLAB. Experimental investigations were carried out in wind tunnel for various velocities and Angle of Attack (AoA) and the results were obtained using digital six component balancing system. Detailed study of both the results shows that the nearctic-ceratopogonidae flexible wing has better lifting properties than the iphiclus-egensis-aile flexible wing at low flapping frequencies and low AoA. For higher flapping frequencies and high AoA, the latter shows better lifting properties than the former.

Spectral Density Method of Liquid Propellant Gauging

My summer internship experience with NASA Kennedy Space Center’s Advanced Engineering Development Branch focused on collecting and processing data to aid in developing Modal Propellant Gauging (MPG) for use in future Orion/SLS missions. The MPG project is an effort to develop a non-invasive low-cost propellant mass gauging technology for application to existing spacecraft propellant tanks in both low-gravity and earth-loading applications. During my internship I constructed a fuel gauging framework through characterizing the modal signature of a composite-overwrap liquid propellant tank used for testing purposes. I accomplished this through: writing and implementing algorithms that apply broadband white noise signals to piezoelectric actuators adhered to the tank surface, processing acoustic data using Fourier analysis, and producing frequency response functions to experimentally determine resonant modes of the tank structure. A limitation of the current MPG technique is that it does not work in environments with changing pressure; during my internship I also made fundamental contributions to the development of the Spectral Density Propellant Gauging Method, a technique that does not depend on the stiffness of the tank walls.

Effects of vibration on passive intermodulation of microwave connector

This paper investigates the generation of passive intermodulation (PIM) in coaxial connectors during vibration. A series of experiments were designed and the simulation model and method were proposed for understanding these phenomena. We found that PIM is mainly influenced by the contact stress and contact surface roughness during vibration. Thus, a power spectral density method is presented to identify the roughness parameter of contact surface based on the Weierstrass–Mandelbrot model, and the simulation model and method were verified by the relative experiments. Eventually, some suggestions for engineering application were provided.

The Fractal Characterization of Mechanical Surface Profile Based on Power Spectral Density and Monte-Carlo Method

The analysis of rough surface morphology plays an important role in the functional characteristics of the contact surface of mechanical parts. Fractal geometry method is more accurate and sensitive than classical statistics model. For fractal representation of rough surface, it is necessary to determine the proper fractal dimension calculation method. In this research, the effect of power spectral density method is studied based on Monte-Carlo method. The fractal dimensions are calculated, the theoretical and the calculated values are compared with paired samples. And the results are compared by non-parametric test. The result shows that power spectral density method has good characterization effect on fractal simulation contour curve. In addition, the precision of fractal dimension of power spectral density is related to fractal dimension of contour theory. The estimation methods of classical power spectral density have different application range.