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.

Control of terminal engagement geometry using generalized vector explicit guidance

Abstract: This paper evaluates a new guidance law termed generalized vector explicit guidance (GENEX). This guidance law has the ability to simultaneously achieve design specifications on miss distance and final missile-target relative orientation. The latter specification may be used to enhance the performance of warheads whose effectiveness is influenced by the terminal encounter geometry. The GENEX guidance law is parameterized in terms of a design coefficient n which is specified by the user and which determines the degree of curvature (and hence control usage) in the trajectory. Feasibility of the GENEX guidance law was demonstrated by its application to a missile terminal homing scenario. Under conditions of ideal sensor information, and assuming a simplified single-lag missile response model, the guidance was shown to perform well against an air target performing evasive maneuvers. The specified zero aspect terminal encounter angle was achieved while simultaneously minimizing the miss distance.

Parallel discrete and continuous wavelet transforms

Abstract: We consider theoretically the optical implementations of both discrete and continuous wavelet transforms. Discrete wavelet transforms (DWTs) require sums (or integrals) of the product of the input function with multiple stored functions (wavelets with various shifts and scales). The inverse DWT requires the same, exceptthe given function is replaced by the wavelet coefficients determined by the DWT. We show that we can store and utilize in parallel large banks of wavelets. This should allow "instantaneous" DWT of functions of a single variable and (relatively) fast DWTs of two-dimensional functions. Of course, the same applies to the inverse DWTs. A true continuous wavelet transform (CWT) must be continuous in both shift and scale. By means of a continuous anamorphic transformation of a one-dimensional signal and a suitable choice of kernel or filter, we can allow a normal two-dimensional optical Fourier transform image processor to perform a CWT.

Turbulence Correlation Length-Scale Relationships for the Prediction of Aeroacoustic Response

Abstract: Expressions to describe the correlation length scales of turbulent inflow to an aerodynamic body are derived as functions of the classic integral length scale and anisotropy correction factors. These one-point parameters are significantly easier to determine experimentally than traditional correlation-scale measurement techniques, which involve multiple probes at multiple locations. As such correlation scales are necessary to properly estimate the aeroacoustic response of the body, such a technique could have substantial benefit in a wide variety of applications. The approach is applied to a recent experimental study examining the response of a stator downstream of a propeller that is itself ingesting broadband turbulence. Results suggest that the derived expressions not only accurately represent correlation length scales, but also enable the accurate prediction of the acoustic output of the stator.