An overview of current Navy programs to develop thrust augmenting ejectors

The primary objective of Navy sponsored research in thrust augmentation is the development of an improved augmenter for V/STOL application. In support of this goal, a data base is being established to provide an accurate prediction capability for use in ejector design. A general technology development of ejectors and associated effects presently is split into the more specific areas of lift and control, since thrust augmenting ejectors may be suitable for both. Research areas examined include advanced diffuser and end wall design; advanced primary nozzles; analytic studies; augmenting reaction controls; and nozzle design

Multifrequency broadband polarized horn antenna

A corrugated conical horn antenna is simultaneously fed a multiplicity of signals, two for each of five frequencies, with each of a pair of signals fed in each of two orthogonal planes for excitation of a desired spherical hybrid mode. The lowest frequency is fed into the horn through orthogonal pairs of colinear slots, each pair being fed by coaxial tee power dividers. Other signals are fed through a circular waveguide connected to the vertex. The highest frequency signals are fed through orthogonal ports near the far end of the circular waveguide. The intermediate frequency signals are fed through orthogonal ports spaced along the waveguide. Filtering is incorporated for each to maintain isolation and low insertion loss

Highly-efficient horn/reflector antenna

Antenna has beam efficiency of 96 percent. Configuration is compact and relatively inexpensive

Bifurcation analysis of frequency locking in a semiconductor laser with phase-conjugate feedback

We present a detailed study of the external-cavity modes (ECMs) of a semiconductor laser with phase-conjugate feedback. Mathematically, lasers with feedback are modeled by delay differential equations (DDEs) with an infinite-dimensional phase space. We employ new numerical bifurcation tools for DDEs to continue steady states and periodic orbits, irrespective of their stability. In this way, we show that the periodic orbits corresponding to the ECMs are connected to the steady state solution associated with the locking range of the laser. We also identify symmetric and nonsymmetric homoclinic orbits and hysteresis in the system

Can capital markets replace banks for funding community development?

Securities markets depend on data. In the absence of data, it is not possible to underwrite risk,> and judgments about risk are crucial to securities pricing. This essay discusses the sort of data> that would be necessary to make underwriting decisions for community development funding.

Marine Shell Ear Disks from Protohistoric Caddo Sites on Stoots Creek, Hopkins County, Texas

In this article, we discuss three engraved marine shell ear disks from two protohistoric (ca. A.D. 1670-1700) Caddo sites on Stouts Creek in Hopkins County, Texas. These rather unique engraved marine shell disks have only been reported from three other archaeological sites in the entire southern Caddo area. Stouts Creek is a tributary to White Oak Creek. The drainage is situated in the modern Post Oak Savanna, at the far western edge of the distribution of Late Caddo Titus phase sites in Northeast Texas. The Stouts Creek marine shell ear disks we report on have been recovered from two different sites in the Stouts Creek valley. One came from a Caddo midden near the Culpepper site (41HP1), a protohistoric Caddo site excavated by The University of Texas in 1931. This particular marine shell disk has a central perforation and a 13.7 mm diameter engraved circle on its outer surface