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 & Mach number. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

Electrostatic nanolithography in polymers using atomic force microscopy.

Abstract: The past decade has witnessed an explosion of techniques used to pattern polymers on the nano (1–100 nm) and submicrometre (100–1,000 nm) scale, driven by the extensive versatility of polymers for diverse applications, such as molecular electronics1,2, data storage3, optoelectronics4, displays5, sacrificial templates6,7 and all forms of sensors. Conceptually, most of the patterning techniques, including microcontact printing (soft lithography)8, photolithography9,10, electron-beam lithography11, block-copolymer templating12,13 and dip-pen lithography14, are based on the spatially selective removal or formation/deposition of polymer. Here, we demonstrate an alternative and novel lithography technique—electrostatic nanolithography using atomic force microscopy—that generates features by mass transport of polymer within an initially uniform, planar film without chemical crosslinking, substantial polymer degradation or ablation. The combination of localized softening of attolitres (102–105 nm3) of polymer by Joule heating, extremely non-uniform electric field gradients to polarize and manipulate the soften polymer, and single-step process methodology using conventional atomic force microscopy (AFM) equipment, establishes a new paradigm for polymer nanolithography, allowing rapid (of the order of milliseconds) creation of raised (or depressed) features without external heating of a polymer film or AFM tip–film contact.

Stress Analysis of Thick Laminated Composite and Sandwich Plates

Abstract: Because of the relatively soft interlaminar shear modulus in high per formance composites, laminated plate theory based on the Kirchhoff hypothesis becomes inaccurate for determining gross plate re...

Role of Blade Passage Flow Structurs in Axial Compressor Rotating Stall Inception

Abstract: The influence of three-dimensional flow structures within a compressor blade passage has been examined computationally to determine their role in rotating stall inception. The computations displayed a short length-scale (or spike) type of stall inception similar to that seen in experiments; to the authors' knowledge this is the first time such a feature has been simulated. A central feature observed during the rotating stall inception was the tip clearance vortex moving forward of the blade row leading edge. Vortex kinematic arguments are used to provide a physical explanation of this motion as well as to motivate the conditions for its occurrence. The resulting criterion for this type of stall inception (the movement of the tip clearance vortex forward of the leading edge) depends upon local flow phenomena related to the tip clearance with the implication that for this and possibly other stall mechanisms the flow structure within the blade passages must be addressed to explain the stability of an axial compression system that exhibits such short length-scale disturbances.