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.

Large signal stability criteria for distributed systems with constant power loads

Abstract: Design oriented criteria are developed for distributed power systems with constant power loads to guarantee stability during large disturbances. The criteria place design constraints on the input filter parameters, such as the Q factor, and constraints on the amount of "ideal" constant power load that a system can support. The criteria are based on Lyapunov stability theory, mixed potential functions, and the existence of equilibrium points. The analytical criteria are validated by means of computer simulations. >

Benchmark for radar allocation and tracking in ECM

Abstract: A benchmark problem for tracking maneuvering targets is presented. The benchmark problem involves beam pointing control of a phased array (i.e., agile beam) radar against highly maneuvering targets in the presence of false alarms (FAs) and electronic counter measurements (ECM). The testbed simulation described includes the effects of target amplitude fluctuations, beamshape, missed detections, FAs, finite resolution, target maneuvers, and track loss. Multiple waveforms are included in the benchmark so that the radar energy can be coordinated with the tracking algorithm. The ECM includes a standoff jammer (SOJ) broadcasting wideband noise and targets attempting range gate pull off (RGPO). The limits on the position and maneuverability of the targets are given along with descriptions of six target trajectories. The "best" tracking algorithm is the one that minimizes a weighted average of the radar energy and radar time, while satisfying a constraint of 4% on the maximum number of lost tracks, The radar model, the ECM techniques, the target scenarios, and performance criteria for the benchmark are presented.

Electric field suppression of epileptiform activity in hippocampal slices

Abstract: 1. The effects of relatively small external DC electric fields on synchronous activity in CA1 and CA3 from transverse and longitudinal type hippocampal slices were studied. 2. To record neuronal activity during significant field changes, differential DC amplification was employed with a reference electrode aligned along an isopotential with the recording electrode. 3. Suppression of epileptiform activity was observed in 31 of 33 slices independent of region studied and type of slice but was highly dependent on field orientation with respect to the apical dendritic-somatic axis. 4. Modulation of neuronal activity in these experiments was readily observed at field strengths < or = 5–10 mV/mm. Suppression was seen with the field oriented (positive to negative potential) from the soma to the apical dentrites. 5. In vivo application of these results may be feasible.

Melting and freezing behavior of indium metal in porous glasses

Abstract: The size-dependent melting and freezing behavior of In metal in porous silica glasses with mean pore diameters between 6 and 141 nm has been studied by differential scanning calorimetry. The melting and freezing temperatures of the pore In were always less than the corresponding bulk values, and varied in inverse proportion to the diameter of the confining silica pores. In the smallest pores the latent heat of fusion was also determined, and found to be about one-third of its bulk value. The observed size dependence of the melting temperature was in good agreement with the predictions of thermodynamic treatments of melting in finite systems, and allowed the solid-liquid interfacial free energy to be estimated for several different geometrical models. The measured latent heat, however, was smaller than expected based on thermodynamic considerations. No evidence for an energy barrier separating the solid from the liquid was found.