294 research outputs found
A Peak Point Theorem for Uniform Algebras on Real-Analytic Varieties
It was once conjectured that if is a uniform algebra on its maximal ideal
space , and if each point of is a peak point for , then .
This peak-point conjecture was disproved by Brian Cole in 1968. Here we
establish a peak-point theorem for uniform algebras generated by real-analytic
functions on real-analytic varieties, generalizing previous results of the
authors and John Wermer
An Application of Storm Mathematical Modeling for Evaluation of Nonpoint Source Water Pollution for a Nonurban Watershed
Today, the engineer is faced with the task of predicting and evaluating the extent of the Nonpoint Sources that pollute our waterways. A mathematical model may be an extremely useful tool in helping the engineer solve problems in the area of water resources. During the course of this investigation, a literature survey related to the Econlockhatchee River Basin and to the STORM mathematical modeling technique for runoff evaluation has been conducted. The latter part of this report deals with an application of the STORM mathematical model for predicting quantity and quality of surface runoff for the Econlockhatchee River Basin located in central Florida
How Well Do We Know the Orbits of the Outer Planets?
This paper deals with the problem of astrometric determination of the orbital
elements of the outer planets, in particular by assessing the ability of
astrometric observations to detect perturbations of the sort expected from the
Pioneer effect or other small perturbations to gravity. We also show that while
using simplified models of the dynamics can lead to some insights, one must be
careful to not over-simplify the issues involved lest one be misled by the
analysis onto false paths. Specifically, we show that the current ephemeris of
Pluto does not preclude the existence of the Pioneer effect. We show that the
orbit of Pluto is simply not well enough characterized at present to make such
an assertion. A number of misunderstandings related to these topics have now
propagated through the literature and have been used as a basis for drawing
conclusions about the dynamics of the solar system. Thus, the objective of this
paper is to address these issues. Finally, we offer some comments dealing with
the complex topic of model selection and comparison.Comment: Accepted for publication in the Ap
Multi-model CFAR detection in FOliage PENetrating SAR images
A multi-model approach for Constant False Alarm Ratio (CFAR) detection of vehicles through foliage in FOliage PENetrating (FOPEN) SAR images is presented. Extreme value distributions and Location Scale properties are exploited to derive an adaptive CFAR approach that is able to cope with different forest densities. Performance analysis on real data is carried out to estimate the detection and false alarm probabilities in the presence of a ground truth
A location scale based CFAR detection framework for FOPEN SAR images
The problem of target detection in a complex clutter environment, with Constant False Alarm Ratio (CFAR), is addressed in this paper. In particular an algorithm for CFAR target detection is applied to the context of FOliage PENetrating (FOPEN) Synthetic Aperture Radar (SAR) imaging. The extreme value distributions family is used to model the data and exploiting the location-scale property of this family of distributions, a multi-model CFAR algorithm is derived. Performance analysis on real data confirms the capability of the developed framework to control the false alarm probability
Loudspeaker analysis : a radar based approach
Recently radar based micro-Doppler signature analysis has been successfully applied in various sectors including defence, biomedical and automotive. This paper presents the novel use of radar micro-Doppler for loudspeaker analysis. The approach offers the potential benefits of characterising the mechanical motion of a loudspeaker in order to identify defects and design issues. Compared to acoustic based approaches, the use of a radar allows reliable measurements in an acoustically noisy end of production line. In addition, when compared witha laser vibrometric approach the use of radar micro-Doppler reduces the number of measurements required and provides direct access to the information of the metallic components of the loudspeaker. In the paper experimental results and analysis of the micro-Doppler signatures of loudspeakers using low cost radar systems are presented. Based on Thiele&Small parameters, the voice coil displacement is modelled and micro-Doppler signatures for a single tone and a sine sweep stimulus are presented. Furthermore, in order to characterise the speaker with a single radar measurement, a methodology to measure mechanical frequency response of loudspeakers is also shown
Partitioned block frequency domain prediction error method based acoustic feedback cancellation for long feedback path
In this paper an innovative method of using Acoustic Feedback Cancellation (PEM based PBFD-AFC) in large acoustic spaces is presented. The system under analysis could vary from Single Source Single Receiver (SISR) to a Multiple Sources Multiple Receivers (MSMR). An environment is representative of (e.g.) churches installations or Public Address (PA) systems, thus involving the presence of one or more microphones and corresponding feedback paths. The Partitioned Block approach consists of slicing the feedback path (e.g the impulse response of the system) to improve the algorithm performance. It can be applied either in the time domain or in the frequency domain, where the latter, called Partitioned Block Frequency Domain, shows faster convergence, lower computational cost and higher estimation accuracy. The results of the proposed framework is compared with the state of the art using real acoustic data showing superior performance with up to 20dB Maximum Stable Gain (MSG) and 30 seconds less convergence time
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