Electromagnetic analysis of a finite reinforced concrete slab

In order to calculate the electromagnetic fields reflected, transmitted, and diffracted by a finite reinforced concrete slab in the presence of a source, a Green's function/method of moments approach has been developed. In doing so, a Green's function solution for a finite and electrically thick dielectric slab is obtained. The Green's function for the arbitrary position of the source and field point is based on the interior Green's function, i.e. the Green's function when the source and the field point are both inside the slab. The solution is two-dimensional, with an electric line source excitation. The first development in this thesis presents an interior electric field Green's function for a thick and finite dielectric slab. The presented solution is based on the separation of variables method which gives an exact solution to a separable slab. The separable slab is closely related to the finite slab. The separable slab solution is expressed in terms of the contribution of the surface wave modes plus the remaining part which is called the "residual wave"' contribution. In order to model a finite slab, the surface wave contribution of the separable slab is modified since the separable slab solution fails to model the finite slab when a surface wave mode is close to resonance. The modification is done by correcting the end cap reflection coefficient for each mode and accounting for the mode conversions. The mode conversions and reflections are characterized by the end cap scattering matrix which is obtained by the method of moments. As a result, the interior Green's function solution for a finite slab is the modified surface wave solution plus the residual wave contribution obtained for the separable slab. The Green's functions for the cases when the source and/or field points are outside the slab are obtained using the interior Green's function and the surface equivalence principle. Having the finite slab Green's function, it is possible to model a finite reinforced concrete slab. Since the metallic rods are assumed to be electrically thick, each metallic rod is replaced by a circular array of thin wires complying with the "same surface area" rule of thumb. To obtain the unknown induced currents on the surface of the thin wires, the method of moments is used in conjunction with the finite slab Green's function. The model is used to investigate the reflection and transmission of electromagnetic waves for some cases of practical interes

Fundamental remote sensing science research program. Part 1: Scene radiation and atmospheric effects characterization project

Brief articles summarizing the status of research in the scene radiation and atmospheric effect characterization (SRAEC) project are presented. Research conducted within the SRAEC program is focused on the development of empirical characterizations and mathematical process models which relate the electromagnetic energy reflected or emitted from a scene to the biophysical parameters of interest

Wind Tunnel Wall Interference Assessment and Correction, 1983

Technical information focused upon emerging wall interference assessment/correction (WIAC) techniques applicable to transonic wind tunnels with conventional and passively or partially adapted walls is given. The possibility of improving the assessment and correction of data taken in conventional transonic wind tunnels by utilizing simultaneously obtained flow field data (generally taken near the walls) appears to offer a larger, nearer-term payoff than the fully adaptive wall concept. Development of WIAC procedures continues, and aspects related to validating the concept need to be addressed. Thus, the scope of wall interference topics discussed was somewhat limited

Recent Experiences in Multidisciplinary Analysis and Optimization, part 1

Papers presented at the NASA Symposium on Recent Experiences in Multidisciplinary Analysis and Optimization held at NASA Langley Research Center, Hampton, Virginia April 24 to 26, 1984 are given. The purposes of the symposium were to exchange information about the status of the application of optimization and associated analyses in industry or research laboratories to real life problems and to examine the directions of future developments. Information exchange has encompassed the following: (1) examples of successful applications; (2) attempt and failure examples; (3) identification of potential applications and benefits; (4) synergistic effects of optimized interaction and trade-offs occurring among two or more engineering disciplines and/or subsystems in a system; and (5) traditional organization of a design process as a vehicle for or an impediment to the progress in the design methodology

Second Microgravity Fluid Physics Conference

The conference's purpose was to inform the fluid physics community of research opportunities in reduced-gravity fluid physics, present the status of the existing and planned reduced gravity fluid physics research programs, and inform participants of the upcoming NASA Research Announcement in this area. The plenary sessions provided an overview of the Microgravity Fluid Physics Program information on NASA's ground-based and space-based flight research facilities. An international forum offered participants an opportunity to hear from French, German, and Russian speakers about the microgravity research programs in their respective countries. Two keynote speakers provided broad technical overviews on multiphase flow and complex fluids research. Presenters briefed their peers on the scientific results of their ground-based and flight research. Fifty-eight of the sixty-two technical papers are included here

Aeronautical Engineering: A continuing bibliography with indexes (supplement 188)

This bibliography lists 477 reports, articles and other documents introduced into the NASA scientific and technical information system in May 1985. The coverage includes documents on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment and systems

Thermoconsolidation and thermal dispersion in deformable porous media

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1994.Includes bibliographical references (p. 226-232).by Cheo K. Lee.Ph.D