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.

Prestressed composite girders. ii: analytical study for negative moment

Abstract: A method for the structural analysis of prestressed composite steel-concrete girders was studied in this paper. The deflections, forces in the prestressing tendons, and strains in the steel beam and concrete slab of composite girders were computed throughout the entire loading range up to failure. Equations are provided for the calculation of the yield and ultimate load capacities of the girders. The developed analytical models were based on the incremental deformation method. The results of the analytical study were compared with test results of several girders. Reasonably good correlations between analytical and experimental results were obtained. Also, the results showed that a substantial increase in the yield and an increase in the ultimate load capacities can be achieved by adding prestressing tendons to the composite girders and prestressing them. It was determined that the most effective construction sequence for prestressed composite girders in negative moment regions is to posttension the composite girders with tendons in the concrete slabs.

Effects of automation and task load on task switching during human supervision of multiple semi-autonomous robots in a dynamic environment.

Abstract: The present study assessed the impact of task load and level of automation (LOA) on task switching in participants supervising a team of four or eight semi-autonomous robots in a simulated 'capture the flag' game. Participants were faster to perform the same task than when they chose to switch between different task actions. They also took longer to switch between different tasks when supervising the robots at a high compared to a low LOA. Task load, as manipulated by the number of robots to be supervised, did not influence switch costs. The results suggest that the design of future unmanned vehicle (UV) systems should take into account not simply how many UVs an operator can supervise, but also the impact of LOA and task operations on task switching during supervision of multiple UVs. The findings of this study are relevant for the ergonomics practice of UV systems. This research extends the cognitive theory of task switching to inform the design of UV systems and results show that switching between UVs is an important factor to consider.

X‐Ray Absorption Fine Structure Spectra and the Oxidation State of Nickel in Some of Its Oxycompounds

Abstract: The structure of the higher oxide forms of nickel (where Ni has a valency greater than +2) is interesting from the standpoint of developing advanced nickel batteries for consumer applications and for electric vehicle propulsion. Xanes spectra of nickel K-edge and X-ray diffraction patterns of several nickel oxycompounds were measured. The shift in energy of the Ni K-absorption edge toward higher values correlates well with the increase in the oxidation state of nickel from +2 to +4 in the compounds studied. The inflection point energy of the Ni pre-edge structure shifts approximately 1 eV per unit change in valency. The results provide evidence which support the assignment that the valency of Ni in [beta]-NiOOH is +3; Ni[sub 3]O[sub 2](OH)[sub 4] and commercial nickel peroxide (NiO[sub 2]) likewise contain trivalent nickel. The edge shift for quadrivalent nickel in KNilO[sub 6] is reported for the first time.

In situ monitoring for fused filament fabrication process: A review

Abstract: Real-time monitoring of the additive manufacturing process offers the promise of guaranteeing product quality and increasing the efficiency of the printing process. This paper summarizes research results for the in situ monitoring of the printing process for the fused filament fabrication process. To have a systematic and comprehensive summary, different methods, devices, and achievements in a range of monitoring systems for 3D printing are described. Sensor types and devices used in the literature for printer health-state monitoring and printing process product quality monitoring are summarized. Discussion of current and future research directions concludes the review.