It is shown that the set of inherent ambiguity functions for context-free languages and the set of ambiguity functions for cycle-free context-free grammars coincide. Moreover for each census function γ of an unambiguous context-free language the least monotone function larger than or equal to γ is an inherent ambiguity function. Both results are based on a more general theorem. Informally it st...

This study provides novel evidence on the role of ambiguity aversion in determining the response of mutual fund investors to historical fund performance information. We present a model of ambiguity averse investors who receive multiple performance-based signals of uncertain precision about manager skill. A key implication of the model is that when investors receive multiple signals of uncertain...

Nocuous ambiguity occurs when a linguistic expression is interpreted differently by different readers in a given context. We present an approach to automatically identify nocuous ambiguity that is likely to lead to misunderstandings among readers. Our model is built on a machine learning architecture. It learns from a set of heuristics each of which predicts a factor that may lead a reader to f...

The connection between the Teager energy operator and the ambiguity function is established in this correspondence after defining the Teager operator over complex-valued signals. This relation allows the use of the Teager energy in estimating the second moment angular bandwidth and the moments of a signal duration (spread) and that of its spectrum.

This correspondence deals with parameter estimation of product signals consisting of hyperbolic FM and chirp factors. A computationally simple algorithm that decouples estimation of the chirp parameters from those of the hyperbolic FM part is presented. It relies on a simple data transformation that removes the hyperbolic FM component, leaving one with the simpler problem of estimating chirp pa...

In this paper we study the B-mode/Doppler duplex imaging problem. We begin by looking at the problem of determining the true velocity vector only. We develop a model for the power spectrum of a signal reeected by a line of point scatterers with a Poisson distribution. We show that with circularly symmetric apertures it is possible to use the expression of that power spectrum to determine the tr...

A novel method for aliasing detection and resolving in the estimation of polynomialphase signal (PPS) parameters is presented. Aliasing is detected using two high-order ambiguity functions (HAFs) of a uniformly sampled PPS embedded in noise. If aliasing occurred, we propose a way of recovering the true parameters from their aliased positions. To that end, a closed-form expression for the true p...

The aim of this paper is to explore the binary sequences with high discrimination using Particle Swarm Optimization with Cauchy Mutation (PSOCM) technique. The cross-ambiguity function method is used to detect the stationary and moving targets in various target detection scenarios. The contour plots of the cross-ambiguity function are computed as a function of delay and Doppler frequency shift....

Abstract AD-MUSIC is introduced to near-field to investigate the bearing and range estimation for the mixed source localization of sinusoidal signal and LFM signal. Firstly, a near-field two-dimensional MUSIC method based on ambiguity function distribution is put forward. Further, a novel Root-MUSIC method which constructs two ambiguity function distribution matrices is proposed for near-field ...

—This paper proposes a novel algorithm of parameter dynamic estimation in near-field Bistatic Multiple-Input Multiple-Output (MIMO) Radar. When a target lies in the nearfield region, the near-field wavefront is spherical, and the plane waves assumption is no valid. The existing methods and signal model based on the far-field assumption are not applicable to this situation. In this paper, we pr...