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: Radar & Sonar. The organization has 2855 authors who have published 3697 publications receiving 83518 citations. The organization is also known as: NSWC.

X-ray reflection topographic study of growth defect and microindentation strain fields in an RDX explosive crystal

Abstract: A reasonably perfect cyclotrimethylenetrinitramine (RDX) explosive crystal has been studied by surface reflection (Berg-Barrett) X-ray topography for the purpose of further elucidating the microstructural basis for hot spots forming in secondary explosives. Topographs were obtained through the base (¯2 1 0) surface of a crystal grown by slow evaporation from an acetone solution. (¯7 2¯1) and (¯6 3¯2) reflections have revealed the central strain field of a large growth defect. This type of defect is proposed to be a suitable internal obstacle for triggering dislocation pile-up collapse during crystal deformation and fracture. Also, extremely localized plastic deformation zones were revealed at Knoop microindentations employed to measure the hardness anisotropy in the (¯2 1 0) crystal surface. A combination of restricted slip systems and cracking is responsible for the significant anisotropy.

A wireless active sensing system for impedance-based Structural Health Monitoring

Abstract: Deployment of Structural Health Monitoring (SHM) systems for permanent damage detection is limited by the availability of sensor technology. The development of a single board computer system is the focus for initial efforts in realizing a fully self-contained active sensor system utilizing impedance-based SHM. The active sensing system interrogates a structure utilizing a self-sensing actuator and the low cost impedance method, and all the data processing, storage, and analysis is performed at the sensor location. A wireless transmitter is used to communicate the current status of the structure. Piezoelectric-based power harvesting allows the sensing system to be completely self-contained and autonomous. With this new low cost, field deployable impedance analyzer, reliance on traditional expensive, bulky, and power consuming impedance analyzers is no longer necessary. Experimental validation of the prototype is performed on a representative structure and compared to traditional methods of damage detection. The benefits of this new system are discussed, along with current research and the path forward to a complete stand alone SHM system.

Repurposing FDA-approved drugs as therapeutics to treat Rift Valley fever virus infection

Abstract: There are currently no FDA-approved therapeutics available to treat Rift Valley fever virus (RVFV) infection. In an effort to repurpose drugs for RVFV treatment, a library of FDA-approved drugs was screened to determine their ability to inhibit RVFV. Several drugs from varying compound classes, including inhibitors of growth factor receptors, microtubule assembly/disassembly, and DNA synthesis, were found to reduce RVFV replication. The hepatocellular and renal cell carcinoma drug, sorafenib, was the most effective inhibitor, being non-toxic and demonstrating inhibition of RVFV in a cell-type and virus strain independent manner. Mechanism of action studies indicated that sorafenib targets at least two stages in the virus infectious cycle, RNA synthesis and viral egress. Computational modeling studies also support this conclusion. siRNA knockdown of Raf proteins indicated that non-classical targets of sorafenib are likely important for the replication of RVFV.

Temperature Effects on Secondary Organic Aerosol (SOA) from the Dark Ozonolysis and Photo-Oxidation of Isoprene

Abstract: Isoprene is globally the most ubiquitous nonmethane hydrocarbon. The biogenic emission is found in abundance and has a propensity for SOA formation in diverse climates. It is important to characterize isoprene SOA formation with varying reaction temperature. In this work, the effect of temperature on SOA formation, physical properties, and chemical nature is probed. Three experimental systems are probed for temperature effects on SOA formation from isoprene, NO + H2O2 photo-oxidation, H2O2 only photo-oxidation, and dark ozonolysis. These experiments show that isoprene readily forms SOA in unseeded chamber experiments, even during dark ozonolysis, and also reveal that temperature affects SOA yield, volatility, and density formed from isoprene. As temperature increases SOA yield is shown to generally decrease, particle density is shown to be stable (or increase slightly), and formed SOA is shown to be less volatile. Chemical characterization is shown to have a complex trend with both temperature and oxidant...

Dislocation mechanics based analysis of material dynamics behavior

Abstract: Mesures de l'influence de la taille des grains sur la contrainte de maclage du fer Armco et d'un acier au carbone. Calcul des deformations par maclage a partir d'un modele constitutif base sur les mecanismes de dislocations en tenant compte des effets de frottement visqueux et de la taille des grains. Comparaison avec des resultats experimentaux pour le fer cubique centre et pour le cuivre cubique a face centree