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.

Encoding Gaussian curvature in glassy and elastomeric liquid crystal solids

Abstract: We describe shape transitions of thin, solid nematic sheets with smooth, preprogrammed, in-plane director fields patterned across the surface causing spatially inhomogeneous local deformations. A metric description of the local deformations is used to study the intrinsic geometry of the resulting surfaces upon exposure to stimuli such as light and heat. We highlight specific patterns that encode constant Gaussian curvature of prescribed sign and magnitude. We present the first experimental results for such programmed solids, and they qualitatively support theory for both positive and negative Gaussian curvature morphing from flat sheets on stimulation by light or heat. We review logarithmic spiral patterns that generate cone/anti-cone surfaces, and introduce spiral director fields that encode non-localized positive and negative Gaussian curvature on punctured discs, including spherical caps and spherical spindles. Conditions are derived where these cap-like, photomechanically responsive regions can be anchored in inert substrates by designing solutions that ensure compatibility with the geometric constraints imposed by the surrounding media. This integration of such materials is a precondition for their exploitation in new devices. Finally, we consider the radial extension of such director fields to larger sheets using nematic textures defined on annular domains.

Compact Difference Scheme Applied to Simulation of Low-Sweep Delta Wing Flow.

Abstract: Computational simulations are presented of the flow over a 50-deg sweep delta wing for angles of attack a = 5,10, and 15 deg. The full Navier-Stokes equations are solved using a sixth-order compact differencing scheme coupled with an eighth-order low-pass spatial filter to provide numerical stability

Broadband Nonlinear Absorbing Platinum 2,2'-Bipyridine Complex Bearing 2-(Benzothiazol-2'-yl)-9,9-diethyl-7-ethynylfluorene Ligands

Abstract: A platinum 2,2′-bipyridine complex (1) bearing 2-(benzothiazol-2′-yl)-9,9-diethyl-7-ethynylfluorene ligands was synthesized and characterized. Its photophysical properties and nonlinear absorption ...

Developments in Titanium Metal Matrix Composites

Abstract: A review is given of developments in the titanium metal matrix composites (MMC) area over the past two decades. Particular topics of discussion include: fibers, matrices, fabrication techniques, mechanical properties of both the fiber and composite, and fractography. It is demonstrated that the increased metallurgical understanding of the composite has led to a product with significantly improved mechanical properties. Conclusions regarding the status of the titanium MMC technology are presented along with suggestions for further metallurgical work necessary to fully realize the potential of these materials.

Grating inscription in picosecond regime in thin films of functionalized DNA.

Abstract: Polymers containing azo-benzene groups are useful holographic recording materials. In these materials the efficient mixed amplitude and phase gratings, frequently accompanied with photoinduced-surface relief gratings, can be inscribed with polarized laser light. The light-induced trans-cis-trans photoisomerization of azo-benzene groups is responsible for optical anisotropy in such systems. The aim of the present work is to study the dynamics of grating inscription in Disperse Red 1 doped deoxyrbonucleic acid- hexadecyltrimethylammonium material (DR1-DNACTMA) using 16 ps laser pulses (532 nm, 1.3 mJ). Results are compared with that obtained for other polymeric matrices loaded with DR1. The dynamics of the grating growth, due to repeated pulses from picosecond laser with 10 Hz repetition rate, was probed by measuring the intensity of the first order of diffraction of a cw He-Ne. We report results in function of the light polarization of writing beams. In this paper we present the first results of the grating inscription in functionalized DNA (in the picosecond pulse regime).