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.

A comparison of the human lumbar intervertebral disc mechanical response to normal and impact loading conditions.

Abstract: Thirty-four percent of U.S. Navy high speed craft (HSC) personnel suffer from lower back injury and low back pain, compared with 15 to 20% of the general population. Many of these injuries are specifically related to the intervertebral disc, including discogenic pain and accelerated disc degeneration. Numerous studies have characterized the mechanical behavior of the disc under normal physiological loads, while several have also analyzed dynamic loading conditions. However, the effect of impact loads on the lumbar disc—and their contribution to the high incidence of low back pain among HSC personnel—is still not well understood. An ex vivo study on human lumbar anterior column units was performed in order to investigate disc biomechanical response to impact loading conditions. Samples were subjected to a sequence of impact events of varying duration (Δt = 80, 160, 320, 400, 600, 800, and 1000 ms) and the level of displacement (0.2, 0.5, and 0.8 mm), stiffness k, and energy dissipation ΔE were measured. Impacts of Δt = 80 ms saw an 18–21% rise in k and a 3–7% drop in ΔE compared to the 1000 ms baseline, signaling an abrupt change in disc mechanics. The altered disc mechanical response during impact likely causes more load to be transferred directly to the endplates, vertebral bodies, and surrounding soft tissues and can help begin to explain the high incidence of low back pain among HSC operators and other individuals who typically experience similar loading environments. The determination of a “safety range” for impacts could result in a refinement of design criteria for shock mitigating systems on high-speed craft, thus addressing the low back injury problem among HSC personnel.

Investigation into State-of-Health Impedance Diagnostic for 26650 4P1S Battery Packs

Abstract: State-of-Health (SoH) is a critical parameter for determining the safe operating area of a battery cell and battery packs to avoid abuse and prevent failure and accidents. Experiments were performed at the US Naval Research Laboratory (NRL) on a 4P1S cell array using pulsed discharge and electrochemical impedance spectra (EIS) to determine a single-point SoH frequency for the array as a whole. Individual cell EIS measurements were taken, as well as measurements of the array as a whole. This work will discuss experimental results to date.

Interaction of Urban Heat Island Effects and Land-Sea Breezes during a New York City Heat Event

Abstract: The state of knowledge of the effects of urban heat islands is advanced through investigation of a heat event in the highly complex coastal environment of New York City (NYC) by using the W...

Optimization of extinction from surface plasmon resonances of gold nanoparticles

Abstract: We present a method to determine the total extinction of laser light due to excitations of the surface plasmon modes in gold nanoparticles, even for very large particle concentrations. The method uses the Mie theory efficiency parameter for single-particle scattering and absorption, a single-particle extinction parameter. We have previously shown that, by properly screening the scattered light, we can determine the extinction of laser light when the beam transverses as many as ten scattering mean free paths in a dense medium, i.e. in the presence of significant multiple scattering. We present the application of the method to the total extinction due mainly to the excitations of the surface plasmon resonance in gold nanoparticles. Although the results obtained from measurements in this multiple-particle medium are explained in terms of the single-particle Mie extinction parameter, we find that the optimum particle size for maximum multiple-scattering extinction is smaller than that for the maximum single-particle extinction parameter predicted by the Mie theory.