Showing papers in "CTIT technical reports series in 1976"

Prediction of Modulation Detectability Thresholds for Line-Scan Displays.

Abstract: : Determination of the modulation detectability threshold for sinusoidal gratings is a prerequisite to several measures of image quality for line-scan imaging systems. To develop predictive models for these thresholds, an experiment was conducted to determine the modulation detectability threshold functions for a range of system parameters typical of medium- to high-resolution low-light-level television systems.

Transmission through a bi-planar slot array sandwiched between three dielectric layers

Abstract: : This report considers transmission through two metallic surfaces provided with small resonant slots where the two screens are separated by a dielectric slab of relative dielectric constant 2. They ar coated on the outside with dielectric slabs of dielectric constant 1 and 3. It is shown that such a configuration can be disigned to yield a transmission curve with band-pass characteristics, i.e., yielding essentially unity transmission coefficient over a certain frequency range (narrow band) for angles of incidence up to as high as 80 deg from broadside in both the E- as well as the H-plane. The value to the Air Force of such surfaces lies in their potential use in metallic radomes. In this connection, it should be pointed out that metallic radomes possess several inherent advantages such as: (a) lightning protection, (b) reduction of precipitation noise, (c) potentially higher mechanical strength. It is demonstrated that the dielectric on the outside by proper design make the bandwidth almost constant with angle of incidence in both the principal planes, while the dielectric between the two slot arrays provides the proper coupling between the two arrays. (Author)

Research on Unsteady Transonic Flow Theory.

Abstract: : Contents: Unsteady Transonic Aerodynamics - An Aeronautics Challenge; Unsteady Local Linearization Solution for Pulsating Bodies at M sub infinity = 1; and Unsteady Local Linearization Solution for Pitching Bodies of Revolution at M sub infinity = 1: Stability Derative Analysis.

Calculation of component forces and moments of arbitrarily banked cruciform missiles with control deflections

Abstract: : This report describes the development of a preliminary version of a single comprehensive code for the engineering calculation of all missile component aerodynamic forces and moments, except minimum drag, for angles of attack up to the unsteady regime The engineering method to be described in this report is composed of five basic procedures: (1) computation of forces and moments, with no external vortices present, for individual fins in the presence of a body at arbitrary angle of attack and bank angle with control deflections; (2) computation of forces and moments induced on individual fins due to the presence of external vortices; (3) calculation, using an empirical method, of the strengths and positions of body vortices generated upstream of the first set of fins; (4) computation, using a vortex tracking method, of the strengths and positions of vortices between the first and second sets of fins; and (5) determination of body forces and moments due to the presence of the fins and vortices

Theoretical studies of high-power ultraviolet and infrared materials

Abstract: : Contents: Stimulated Raman scattering (enhanced Stokes gain and effects of anti-stokes and parametric phonon processes); Enhanced stimulated Raman scattering and general three-boson parametric instabilities; Theory of laser-materials damage by enhanced stimulated Raman scattering; Surface roughness and the optical properties of a semi-infinite material (the effect of a dielectric overlayer); Appendix (construction of the green's functions for the electromagnetic wave equation); Theory of laser heating of solids (metals); Current status of high-intensity vacuum ultraviolet materials; Impurity absorption in halide window materials.

Replacement of RT-524/246 Transmitter Tubes by Transistor Inserts

Abstract: : The RT-524 and RT-246 VHF vehicular radios are in the field in large numbers. These will have to be maintained for the next 10-20 years or longer. In order to assure maintainability, and also to increase the reliability of the radio, replacement of transmitter tubes by transistor inserts was explored. A model was successfully designed, constructed and tested. In addition to improved reliability, another advantage is that the noisy fan does not operate under normal conditions. Therefore, the position of the radio is not given away in a quiet environment. A further advantage is that a 100% transmit duty cycle is possible.

Analytical Applications of Electron Spin Resonance.

Abstract: : This report reviews applications of electron spin resonance (ESR) to chemical analysis. Basic theory of ESR and the instrumentation required for chemical analysis is discussed. The theory of ESR absorption is presented for the general case, and simplified forms for specific conditions are derived. These are applicable to solid, liquid and gas phase analysis of paramagnetic materials. Finally, specific techniques which utilize ESR are described. The application of the computer for calculation of the double integral of the ESR lineshape and suggestions for optimizing accuracy of the determinations are presented. (Author)