Signal-to-noise ratio threshold effect in track before detect

Track before detect (TBD) refers to simultaneous detection and tracking using unthresholded sensor responses over time. The motivation for TBD is its capacity to deal with low signal-to-noise ratio (SNR) targets. Previously, the achievable error for TBD has been established using Cramer?Rao analysis. Although computationally simple the Cramer?Rao bound is not useful at low SNR as it does not predict the threshold effect. A more accurate notion of the achievable performance at low SNRs is provided by the computationally more complicated Barankin bound. The computational complexity of the Barankin bound arises from the need to optimise over a number of test points, with the tightness of bound increasing with the number of test points. An approximation to the Barankin bound is proposed which permits the use of multiple test points with reasonable computational expense. The improvements in threshold SNR prediction offered by the proposed bound are demonstrated in numerical examples.     

Instantaneous frequency estimation of quadratic and cubic FMsignals using the cross polynomial Wigner-Ville distribution

The cross polynomial Wigner-Ville distribution (X-PWVD) is applied to instantaneous frequency (IF) estimation of polynomial FM signals. The X-PWVD is used in a simple iterative algorithm, similar to the one proposed by Boashash and O'Shea (see ibid., vol.41, no.3, p.1439, 1993) for the cross Wigner-Ville distribution (X-WVD). The advantage of the X-PWVD over the polynomial Wigner-Ville distribution is that the former is linear with respect to the observed signal and as a result it attains the Cramer-Rao bound at lower signal-to-noise ratios (SNRs)     

A correction of E-model in quality estimation of packetized speech signal

This letter presents correction of E-model for the quality estimation of the packetized speech signal in the case of burst packet loss. The current estimation depends on the method of calculation, i.e. on the duration of speech signal segment, which is to be packetized by one packet. This inconsistency in estimation is described, and the correction of this imperfection is proposed. It is explained that the Packet-loss Robustness Factor is dependent, besides coder, on the duration of speech signal segment, which is packetized by one packet.     

Wideband Acousto-optical Bragg Transducer for Integrated Optics

Abstract

The electrical and acousto-optical characteristics of modified chirp surface acoustic wave Bragg transducers for planar optical waveguides in YZ (Y cut, Z propagating) LiNbO₃ are described theoretically and experimentally.     

An Optical Lock-in Technique as Applied to an Acousto-optic Integrated Spectrum Analyser

Abstract

A new signal coding technique is presented here for use with the existing integrated optical spectrum analyser structure. Modifications to the basic device are implemented, and shown to have a theoretical and an experimental dynamic range increase of 10–20 decibels (dB). Such an increase would bring the overall device dynamic range to 40–50 dB.     

Application of a master meter systemto assure crude oil and natural gas quality during transportation

This paper discusses an example of the master meter system (MMS), used in the oil and gas industry with the purpose of validating the performance of custody transfer meters. The system can also be used to determine if there are any changes such as the deposition of wax or asphaltic material (in the case of crude oil) or liquids (in the case of natural gas). According to current standards, custody transfer measurements must pass periodic verification of measurement performance, the process which is known as meter proving. This paper presents the construction and key parts, as well as the main functionalities of MMS which comply with the most rigorous requirements for custody transfer. This is achieved by using a novel instrumentation with high level of accuracy, appropriate flow computer and HMI (Human Machine Interface) application developed to support supervision and control of the proving process.     

Anisotropic aberrations in planar waveguide lenses

An approximate analysis of anisotropic aberrations in waveguides lenses on lithium niobate is presented. The causes of anisotropic aberrations are discussed. Anisotropic aberrations of a single refracting surface are studied and a general expression for an optical system consisting of m surfaces is derived. Numerical examples provided illustrate the anisotropic aberrations in various spherical aberration-corrected waveguide lenses     

Attentional Effects of Counterpredictive Gaze and Arrow Cues.

The authors used counterpredictive cues to examine reflexive and volitional orienting to eyes and arrows. Experiment 1 investigated the effects of eyes with a novel design that allowed for a comparison of gazed-at (cued) target locations and likely (predicted) target locations against baseline locations that were not cued and not predicted. Attention shifted reflexively to the cued location and volitionally to the predicted location, and these 2 forms of orienting overlapped in time. Experiment 2 discovered that another well-learned directional stimulus, an arrow, produced a different effect: Attention was shifted only volitionally to the predicted location. The authors suggest that because there is a neural architecture specialized for processing eyes, gaze-triggered attention is more strongly reflexive than orienting to arrows. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The viscosity effect on autoacceleration of the rate of free radical polymerization

The reaction kinetics at 70°C were investigated for the suspension polymerization of methyl methacrylate initiated by benzoyl peroxide in the presence of variable amounts of dodecyl mercaptan. A dilatometric method designed to follow a suspension polymerization was used. It showed that the autoacceleration of the rate of polymerization begins at higher conversions and becomes less pronounced as the concentration of chain transfer agent is increased. The investigations focused on the determination of the viscosities of the reaction mixtures at the onset of autoacceleration. It was concluded from the flow curves obtained for different reaction mixtures that there exists a critical solution viscosity at which the autoacceleration begins, which supports the accepted theory about the nature of this phenomenon. Measured at a shear rate of 10,000 s^?1 and at 25°C this viscosity was found to equal 0.6 poise regardless of the molecular weight of the growing polymer.     

Evaluation and improvement of antioxidant and antibacterial activities of supercritical extracts from clove buds

For the first time, extracts from clove buds obtained by supercritical carbon dioxide extraction were screened for antioxidant and antibacterial activities. Additionally, antioxidant and antibacterial activities of extracts obtained by the supercritical extraction of the clove bud–oregano leaf mixtures were studied. Supercritical extract of pure clove had the highest eugenol (64%) and total phenolic content (530.56 mg GAE/g_extract). All extracts had antioxidant activity comparable to synthetic antioxidants against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and formation of peroxides. Presence of 0.6% and 5% of oregano extract in the clove extracts obtained from the clove–oregano plant mixtures improved their antioxidant activity with respect to the extract from pure clove. Clove extract showed moderate antibacterial activities against selected Staphylococcus and Enterococcus bacterial strains. Presence of 50% of the oregano extract improved antibacterial activity of clove extract against all tested strains and resulted in a synergistic antibacterial activity against Methicillin-resistant Staphylococcus haemolyticus strain (MIC ? 1.25 μg/mL). Study demonstrated great potential of supercritical clove extract as natural functional ingredient and the possibility of increasing its antioxidant and antibacterial efficiencies in order to apply lower concentrations and to reduce undesirable flavour notes and toxicological effects in final products.