Issue 10 Volume 41 May 16, 2003

element method, scalars, and marching the discontinuous Galerkin Eikonal approximation.
CASI
Galerkin Method; Discretization (Mathematics); Eikonal Equation; Triangulation; Manifolds (Mathematics); Curves
(Geometry); Isoparametric Finite Elements; Discontinuity
20030032918 Ohio State Univ., Columbus, OH
Optimal Array Geometries for Wideband DOA Estimation
Baysal, Ulku; Moses, Randolph L.; Oct. 2001; 13 pp.; In English
Contract(s)/Grant(s): DAAH-96-C-0086
Report No.(s): AD-A410303; No Copyright; Avail: CASI; A03, Hardcopy
We consider the role of array geometry on the Direction of Arrival (DOA) estimating performance of the array where the
impinging signal is wideband. We concentrate on arrays that have isotropic performance. An isotropic array is one whose
Cramer Rao bound (CRB) on the DOA of a single source is uniform for all angles. We derive the necessary and sufficient
conditions on the location of array elements so that the array is isotropic. Both planar arrays and three dimensional arrays are
considered. We also present several designs of isotropic planar and volume arrays and give example geometries.
DTIC
Arrays; Signal Processing
20030032946 Instituto Nacional de Pesquisas Espacias, Sao Jose dos Campos, Brazil
Heuristic Location-Allocation for Facilities Location Problems
Arakaki, Reinaldo Gen Ichiro; 2003; 72 pp.; In Portuguese
Report No.(s): INPE-9572-TDI/837; Copyright; Avail: CASI; A04, Hardcopy
New location-allocation heuristic (LAH) algorithms applied in facility location problems are presented in this thesis. Such
algorithms approach is based on clustering and its main objective is to find out a facility (object) in a space by minimizing
a function. The LAH developed throughout this work was employed in two problems: the first problem is the Maximal
Covering Location Problem (MCLP) and the second one is the Capacitated p-Median Problems (CPMP) with the purpose of
a possible integration to Geographic Information Systems (GIS). A set of test problems was chosen to validate this LAH. Good
results were obtained for small and large-scale problems in MCLP cases. Good results were also obtained for small-scale
problems in CPMP cases. The LAH were also applied as a mutation process in Constructive Genetic Algorithms for the same
problems. The good results demonstrate that LAH, being quick and fast, may be usefully applicable to GIS.
Author
Genetic Algorithms; Geographic Information Systems; Heuristic Methods; Position (Location); Problem Solving
20030032955 Army Research Lab., Adelphi, MD
Shockwave and Muzzle Blast Classification Via Joint Time Frequency and Wavelet Analysis
Mays, Brian T.; Sep 2001; 14 pp.; In English; Original contains color illustrations
Report No.(s): AD-A410324; No Copyright; Avail: CASI; A03, Hardcopy
This paper will apply various joint time-frequency (JTF) and wavelet techniques to extract features from shockwave and
muzzle blast signatures for the purpose of classification. The techniques used will include short-time Fourier transform
(STFT), Smoothed Pseudo Wigner-Ville distribution (SPWVD) and wavelet multi-scale analysis. A projectile’s trajectory can
be estimated by measuring the arrival times of the acoustic energy at several locations in space. In the case of a supersonic
projectile fired from a gun, both the acoustic shockwave and muzzle blast may be observed. For acoustic sensor systems
attempting to determine a projectile’s trajectory, the challenge is to first, correctly classify the transient signal as either a
shockwave or a muzzle blast and then, calculate the direction-of-arrival via appropriate arrival times across a sensor array. This
can be extremely challenging when the shockwave has lost substantial high frequency content. The change in spectral
characteristics can stem from propagation over a long distance, propagation over snow covered terrain or arriving from a
non-perfect reflector. An incorrect classification will result in large estimation errors of the projectile’s trajectory. Experimental
results are presented for proper classification over various miss distances from the sensors for all of the above techniques
mentioned.
DTIC
Fourier Transformation; Sound Detecting And Ranging
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