Naval Surface Warfare Center

About: Naval Surface Warfare Center is a facility organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Sonar & Radar. The organization has 2855 authors who have published 3697 publications receiving 83518 citations. The organization is also known as: NSWC.

Decontamination of a hard surface contaminated with Bacillus anthracisΔSterne and B. anthracis Ames spores using electrochemically generated liquid-phase chlorine dioxide (eClO2).

Abstract: Aims: To evaluate the inactivation of Bacillus anthracisΔSterne and Ames spores using electrochemically generated liquid-phase chlorine dioxide (eClO2) and compare two sporulation and decontamination methods with regard to cost, safety and technical constraints. Methods and Results: Spores were prepared via agar and broth methods and subsequently inoculated and dried onto clean, autoclave-sterilized glass coupons. Bacillus anthracis spore inactivation efficacy was evaluated using the modified three-step method (AOAC 2008.05) and a single-tube extraction method. Spores (7·0 ± 0·5 logs) were inactivated within 1 min at room temperature using freshly prepared eClO2. Bacillus anthracisΔSterne spores decreased in size after eClO2 treatment as measured using a Beckman Coulter Multisizer. Conclusions: eClO2 saturation of a hard surface was an effective B. anthracis sporicide. Broth sporulation and the single-tube extraction method required less time and fewer steps, yielded a higher percentage of phase-bright spores and showed higher spore recovery efficiency compared with AOAC 2008.05, making it more amenable to biosafety level 3 (BSL3) testing of virulent spores. Significance and Impact of the Study: Two test methods demonstrated the sporicidal efficacy of eClO2. A new single-tube extraction test protocol for decontaminants was introduced.

Crushing of an Elastic-Plastic Ring Between Rigid Plates With and Without Unloading

Abstract: Load-deflection curves are computed for an elastic-plastic ring that is slowly crushed between frictionless, rigid plates (platens). The ring is assumed to be inextensional with plane sections remaining plane and to obey a bi-linear stress-strain law with isotropic hardening. These assumptions lead to a local nonlinear moment-curvature relation identical to that developed by Liu et al. When inserted into the exact equation for moment equilibrium, this constitutive relation yields a second-order, nonlinear ordinary differential equation for the angle a between the deformed centerline of the ring and the horizontal. The numerical solution of this equation, which uses a combined penalty-continuation method, along with an auxiliary equation relating the vertical deflection to a, leads to overall load-deflection curves that depend on two dimensionless parameters, λ and μ. The first is the ratio of the plastic modulus to the elastic modulus; the second measures the ratio of plastic to elastic effects. As μ-0, the overall load-deflection curve of Frish-Fay for the elastica is recovered; as μ→∞, that of DeRuntz and Hodge for a rigid-perfectly plastic ring is recovered. Three scenarios are considered: I 0 , in which an initially straight, stress-free beam is bent elastically into a ring and then crushed; H 0 , in which an initially stress-free ring is crushed; and III 0 , in which an initially straight beam is bent first elastically and then elastically-plastically into a ring and then crushed. Results for scenario II 0 are shown to agree well with experiments of Reddy and Reid if λ=0.01 and μ = 10 and 20 and with experiments of Avalle and Goglio if λ=0.02 and μ = 11. In scenarios I 0 and II 0 , the effects of unloading prove to be small, reinforcing a similar conclusion of Liu et al., who considered the large-deflection of an elastic-plastic cantilever under a tip load. If no unloading is assumed, a more analytical treatment is possible, as shown in the second part of the present paper. The model predicts that the ring always remains in full contact with the platens, in agreement with recent experiments by Avalle and Goglio on annealed aluminum tubes. Pull-away from the platens also observed in experiments is ascribed to end effects which cannot be modeled by a one-dimensional beam theory. However, it is argued that, even if there is pull-away, the effect on the overall force-deflection relation must he small because in both cases the forces exerted by the platens are concentrated at the ends of the contact region. Moving pictures of successive stages of deformation of the ring showing the formation of plastic loading and unloading zones in all three scenarios may be found on the web site www.people.virginia.edu/∼jgs/ring.html.

Electrical probing of surface and bulk traps in proton-irradiated gate-assisted lateral PNP transistors

Abstract: The effects of 46 MeV proton irradiation-induced trap generation and its impact on the electrical characteristics of gate assisted lateral PNP transistors (GLPNP) are investigated for the first time. At proton fluence as high as 10/sup 12/ p/cm/sup 2/ the devices show a negligible current gain degradation, and at 10/sup 13/ p/cm/sup 2/ the devices are still functional. The excellent radiation hardness is attributed to the much thinner gate oxide than in conventional lateral PNPs and its gate assisted operation. By changing the gate bias, and modulating the surface status from accumulation to inversion, the surface traps can be electrically probed from the I-V characteristics. A base current peak is observed after radiation, and is understood using 2D device simulation to be a result of the increase in oxide charge and surface trap density, in conjunction with the different SRH recombination rate limiting mechanism in presence of high density traps. The inverse mode operation is shown to be a useful tool for probing the bulk traps.

Nonequilibrium effects in oblique shock-wave reflection

Abstract: Extension du schema eulerien du second-ordre de Godunov pour traiter le probleme d'un melange de gaz hors d'equilibre chimiquement reactif. Application a de l'air a haute temperature. Calcul des reflexions d'ondes de choc planes, obliques