Wright-Patterson Air Force Base

About: Wright-Patterson Air Force Base is a other organization based out in Wright-Patterson AFB, Ohio, United States. It is known for research contribution in the topics: Laser & Microstructure. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

Gadolinium Molybdate, a New Type of Ferroelectric Crystal

Abstract: Ferroelectric properties in gadolinium molybdate are shown to originate from a new mechanism completely different from that in conventional ferroelectric materials. In this crystal the spontaneous polarization results from an elastic instability which gives rise to a spontaneous strain in the original piezoelectric paraelectric phase. The dielectric permittivity of the clamped crystal ($\ensuremath{\epsilon}_{33}^{x}$) is low and independent of temperature, while the elastic constant ($c_{66}^{E}$) shows a strong temperature dependence with a marked anomaly at the Curie point.

Life Prediction for Resin-Matrix Composite Materials

Abstract: Available methods for predicting the fatigue life of resin–matrix composite materials are reviewed. These include empirical, residual strength degradation, stiffness degradation, and actual damage state based theories. The residual strength degradation fatigue theories are discussed in detail. They are shown to possess a damage metric that can be summed cycle-by-cycle to give cumulative damage theories. Moreover, they exhibit the sudden death behavior observed in some experimental data. The stiffness degradation theories are shown to be logical generalizations of the residual strength degradation fatigue theories. Statistically rigorous procedures for determining how well particular fatigue theories fit experimental data are presented. Their use for checking for panel-to-panel fabrication variability and different fatigue theory fits is illustrated. Finally, a procedure for determining whether a particular theory is statistically valid is discussed and used to show that the residual strength degradation based fatigue models may not be valid for composite materials.

Three-photon-absorption-induced fluorescence and optical limiting effects in an organic compound

Abstract: Three-photon-absorption-induced frequency-upconversion f luorescence emission has been observed in a solution of 2,5-benzothiazole 3,4-didecyloxy thiophene (BBTDOT) in tetrahydrofuran, pumped with 10-ns Q-switched 1.06-microm laser pulses. The spectral peak of the observed fluorescence emission is located in the 450-480-nm range, and the intensity dependence of the visible emission on the IR excitation obeys the cubic law. At a higher solute concentration (0.18 M/L) and moderate IR excitation intensity levels (50-200 MW/cm(2)), obvious optical limiting behavior has been observed as a result of three-photon absorption. The measured nonlinear absorption coeff icient and the corresponding molecular three-photon-absorption cross section are gamma= 2.7 x 10(-18) cm(3)/W(2) and sigma'(3) = 8.8 x 10(-76) cm(6) s(2), respectively.