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.

Adaptive NbN/Ag coatings for high temperature tribological applications

Abstract: article i nfo Nanocomposite films that consist of niobium nitride with silver nanoinclusions were created using unbal- anced magnetron sputtering to investigate their potential as adaptive, friction reducing coatings. The coatings were tribotested against a Si3N4 counterface in the 25 to 1000 °C temperature range. The coatings displayed coefficients of friction in the 0.15 to 0.30 range at T>700 °C. Post-wear testing structural and chemical char- acterization revealed that, in the low to mid-temperature range, silver migrated to the surface to reduce friction. At higher temperatures, oxygen, silver and the transition metal reacted to form lubricious binary metal oxide phases (silver niobate) in addition to pure silver. In situ Raman spectroscopy measurements were taken during heating and wear testing at 750 °C to identify the evolution of phases in the coatings surface and in the wear track. The analysis of the in situ Raman spectroscopy data revealed the various stages of formation of these binary metal oxides. The coatings were subsequently doped with MoS2 to investigate the effect of the introduction of a low temperature lubricant. The addition of MoS2 did not appreciably reduce the room temperature coefficient of friction, likely due to the miscibility of this compound with the transition metal nitride. However, the coefficient of friction was significantly reduced at high temperatures because of the synergistic lubricious effect of silver niobates and molybdates.

Bioinspired Material Approaches to Sensing

Abstract: Bioinspired design is an engineering approach that involves working to understand the design principles and strategies employed by biology in order to benefit the development of engineered systems. From a materials perspective, biology offers an almost limitless source of novel approaches capable of arousing innovation in every aspect of materials, including fabrication, design, and functionality. Here, recent and ongoing work on the study of bioinspired materials for sensing applications is presented. Work presented includes the study of fish flow receptor structures and the subsequent development of similar structures to improve flow sensor performance. The study of spider air-flow receptors and the development of a spider-inspired flexible hair is also discussed. Lastly, the development of flexible membrane based infrared sensors, highly influenced by the fire beetle, is presented, where a pneumatic mechanism and a thermal-expansion stress-mediated buckling-based mechanism are investigated. Other areas that are discussed include novel biological signal filtering mechanisms and reciprocal benefits offered through applying the biology lessons to engineered systems.

A population pharmacokinetic analysis of the penetration of the prostate by levofloxacin.

Abstract: Prostatitis has remained a pathological entity that is difficult to treat. Part of the difficulty revolves about the putative offending pathogens. For acute prostatitis, members of the Enterobacteriaceae, particularly Escherichia coli, play a central role, while intracellular pathogens such as Chlamydia are more frequently seen in chronic prostatitis. Consequently, a drug needs to be able to penetrate to this specialized site in both the acute and chronic infection forms of the disease and also have potent activity against the most common causative pathogens, both intracellular and extracellular. Levofloxacin has such an activity profile. We wished to document its ability to penetrate to the site of infection. Patients undergoing prostatectomies were administered 500 mg of levofloxacin orally every 24 h for 2 days prior to surgery, and then on the day of surgery, 500 mg was administered as an hour-long, constant-rate intravenous (i.v.) infusion. A set of blood samples was obtained as guided by stochastic optimal design theory. Prostate biopsy times were determined by randomizing subjects into one of four groups, based on the interval after the i.v. dose. All plasma and prostate drug concentrations were comodeled by a population modeling program, BigNPEM, implemented on the Cray T3E Supercomputer housed at the Supercomputer Center at the University of California at San Diego. Penetration was determined as the ratio of the area under the concentration-time curve (AUC) of levofloxacin in the prostate to the plasma levofloxacin AUC. When calculated from the mean population parameters, this penetration ratio was 2.96. We also performed a 1,000-subject Monte Carlo simulation from the mean parameter vector and covariance matrix. The mean penetration ratio here was 4.14 with a 95% confidence interval of 0.20 to 19.6. Over 70% of the population had a penetration ratio in excess of 1.0. Levofloxacin adequately penetrates a noninflamed prostate and should be evaluated for the therapy of prostatitis.

Large Eddy Simulation of Plasma-Based Control Strategies for Bluff Body Flow

Abstract: Large eddy simulation was used to explore plasma-based control strategies for the flow past a circular cylinder in crossflow at a Reynolds number of 10,000 Solutions were obtained to the Navier-Stokes equations, using a simple phenomenological model to represent plasma-induced body forces imparted by actuators on the surrounding fluid The numerical method used a high-fidelity time-implicit scheme, and an overset grid approach Two fundamentally different control strategies were investigated, consisting of larger actuators that produced a wall-jet-like flow, and smaller actuators that perturbed the unstable shear layers near the separation location The larger actuators achieved control via a "Coanda" effect, and were operated both continuously and in a pulsed manner For pulsed cases, two different bistable states with nonzero time-mean lift were identified All control cases resulted in at least a 50% decrease in drag, as well as elimination of oscillatory lift Comparison is made with available experimental data for the baseline case where no control was enforced Features of the control flowfields are described, and resultant solutions are compared with each other

Highly Loaded Axial Flow Compressors: History and Current Developments

Abstract: This paper discusses approaches taken over many years to achieve very high loading levels in axial-flow compressors. These efforts have been associated predominantly with aircraft turbine engines. The objective has been to reduce the size and weight of the powerplant, to increase its simplicity and ruggedness, and, whenever possible, to reduce cost. In the introduction, some fundamentals are reviewed that indicate that increased work per stage can only be obtained at a cost of increased Mach number, increased diffusion, or both. The earliest examples cited are some ambitious development programs of the 1950s and 1960s. Some innovative schemes to increase diffusion limits are described that took place in the 1960s and 1970s. Major advancements in dealing with higher Mach number were made in the 1980s. Finally, a few thoughts directed toward potential future developments are presented.