Ugur Guven

Detection of Ocean Wave Parameters Using Synthetic Aperture Radar (SAR) Data

This study describes the estimation of spherical wave parameters that appears in Synthetic Aperture Radar (SAR) images acquired over the coast of Chukk, Micronesia. The main causes for the interaction of SAR signals with ocean waves can be retrieved through the Bragg scattering mechanism. Dominant wavelengths were retrieved by means of Fast Fourier Transform (FFT) analysis in terms of peak frequency responses. Sea surface slopes were then obtained from the dispersion relation with consideration of different water wave conditions for each subset area, and wave heights were estimated with the use of dominant wavelengths and sea surface slopes. The work presented in this paper may be useful to retrieve the various wave parameters over different regions. The method used is a novel technique to correlate the relationship between SAR image parameters and dispersion relation.

Aerothermodynamics of a hypersonic vehicle with a forward-facing parabolic cavity at nose

Numerical experiments are carried out using commercially available Navier–Stokes solver to investigate the effect of forward-facing parabolic cavity on the heat fluxes over a spherical nosed blunt body. A wide range of parabolic cavities with depths varying between 2 and 10 mm placed at the nose of sphere-cylinder with base diameter 40 mm and overall length 70 mm have been investigated. The ratio of the cavity radius at intersection with y-axis to depth of cavity (r/d) of these cavities varies from 1.5 to 2.5. All computations have been done at a freestream Mach number of 6.2 and sea level atmospheric conditions assuming air to be a thermally perfect gas. The steady-state solutions obtained through time marching solution of axisymmetric Navier–Stokes equations suggest that the total heat transfer rate, area weighted average heat flux and the peak heat fluxes to the body can be favorably reduced for shallow parabolic cavities.

Nuclear Fusion and the Moon as a Source of Power for the World - Possibility of 3He Fusion and the International Quest for the Moon

One of the biggest challenges that the world faces is definitely the need for more energy. As the world’s fossil fuel supplies dwindle down, it becomes more and more important to find clean sources of energy that can also fulfill the global demand for more energy. Fortunately, aerospace technology can be of use, as the moon can be used to harvest 3He, which can be a clean source of nuclear fuel for fusion reaction on Earth, as well as on the moon. This paper will demonstrate that the concept of moon mining needs to be explored further as 3He can be of great use for solving the world’s energy needs.

Usage of Nuclear Reactors in Space Applications - Space Propulsion and Space Power Concepts

Especially in the 21st century, the space has become the actual final frontier for mankind. The possibilities are endless, as there are a lot of frontiers that can be covered in space exploration. Unfortunately, two main problems prevail in space exploration. The first problem is that the distances that need to be covered are extremely large and the second problem is the need for energy for any outpost installation in space. Fortunately, the availability of nuclear technologies allow for solution of these problems. In this paper, it is demonstrated that by using nuclear technology, traveling time can be greatly reduced and the energy requirements of the astronauts onboard a spacecraft or a space station can be met.