NASA Scientific and Technical Aerospace Reports

A new approach to making voiced/unvoiced decisions is presented. The technique is very accurate and dynamically adapts
to a wide range of environments. Reliable decisions are achieved by using a weighted sum of multiple speech parameters.
Instead of using discriminant analysis to determine the optimal weights, voiced and unvoiced frames are separated into two
clusters by a multivariate clustering algorithm. Since cluster analysis requires no prior voicing information, the decision rule
is computed from the incoming speech rather than from a training set. An adaptive clustering algorithm is derived which
continuously adjusts the weights in response to changing speech characteristics.
Author
Multivariate Statistical Analysis; Cluster Analysis; Algorithms; Discriminant Analysis (Statistics); Distortion; Noise (Sound)
20060001728 Naval Underwater Systems Center, New London, CT, USA
High Resolution Time Delay Estimation
Kirsteins, Ivars P.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP ‘87); Volume 1;
1987, pp. 12.5.1 - 12.5.4; In English; See also 20060001583; Copyright; Avail.: Other Sources
A new method is presented for estimating the arrival times of deterministic signal pulses that are separated by less than
the duration of the signal autocorrelation function. The method is based on the observation that if the signal has a flat
band-limited spectrum, then the maximum-likelihood estimator for the signal time of arrivals can be approximately
implemented as an unweighted least-squares exponential fitting problem. An improved linear prediction algorithm for high
resolution exponential parameter estimation is then used to estimate the time arrivals. The proposed method is tested via
computer simulation and it’s performance is compared against the Cramer-Rao lower bound.
Author
Time Lag; High Resolution
20060001729 Centre National de la Recherche Scientifique, Saint Martin d’Heres, France
Time Delay Estimation by Autoregressive Modelization
Pallas, M. A.; Martin, N.; Martin, J.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP
‘87); Volume 1; 1987, pp. 12.6.1 - 12.6.4; In English; See also 20060001583; Copyright; Avail.: Other Sources
From an active underwater acoustics experiment, we intend to estimate the time delays of the multipath propagation, in
the case where the time differences of arrival are not large enough to be treated by classical methods. After estimating the
propagation filter transfer function, we apply the autoregressive modelization to these frequential data. We deduce the delays
values from the poles locations of the AR model. Simulations of the processing are presented. Finally, the method is applied
to real data.
Author
Time Lag; Simulation; Transfer Functions
20060001820 Maryland Univ., Baltimore, MD USA
Strategies and Heuristics Used by the UMBCTAC Agent in the Third Trading Agent Competition
Ding, Li; Finin, Tim; Shi, Youngmei; Zou, Youyong; Ding, Zhongli; Pan, Rong; Jan. 1, 2005; 8 pp.; In English; Original
contains color illustrations
Contract(s)/Grant(s): F30602-97-1-0215
Report No.(s): AD-A440305; No Copyright; Avail.: Defense Technical Information Center (DTIC)
The UMBCTAC agent was one of the top ranked agents in the third international Trading Agent Competition (TAC’02).
This paper describes and evaluates the key heuristics used by UMBCTAC. including the early bird heuristic, the balance
heuristic, and the separation heuristic. We developed a simple gain- risk model to search safe and profitable allocations for
hotel rooms and airline tickets. We also used a novel probabilistic approach to dynamically allocate entertainment tickets and
bid in entertainment auctions. We conclude with a description of ongoing and planned work.
DTIC
Competition; Heuristic Methods; Probability Theory
20060001825 Maryland Univ. Baltimore County, Catonsville, MD USA
Estimation of Subpixel Target Size for Remotely Sensed Imagery
Chang, Chein-I; Ren, Hsuan; Chang, Chein-Chi; D’Amico, Francis; Jensen, James O.; Jun. 1, 2004; 13 pp.; In English
Report No.(s): AD-A440318; No Copyright; Avail.: Defense Technical Information Center (DTIC)
One of the challenges in remote sensing image processing is subpixel detection where the target size is smaller than the
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