Kalman Filter Equalization For QPSK Communications

The discrete complex Kalman filter is considered as an equalizer for quadrature phase-shift keyed (QPSK) systems in the presence of additive noise and InterSymbol interference (ISI). When the channel is unknown, an adaptive Kalman equalizer is used in which the channel complex tap gains are estimated by decision feedback. Copyright © 1976 by The Institute of Electrical and Electronics Engineers, Inc

Experimental investigation of CFRP-strengthened steel beams with web openings

The introduction of web openings in existing steel floor beams is a common occurrence in practice. Such modifications are often necessary to accommodate additional services driven by a change of building use, thus extending the service life of the structure. Depending on their size and location, openings in the web can present a major challenge to the strength and stiffness of the beam. Strengthening around an opening is often necessary to maintain the required performance of the floor beam, traditionally this is affected via application of additional steel plate, either bolted or welded. This paper focusses on the novel application of carbon fibre reinforced polymer (CFRP) to the problem of strengthening web openings, taking advantage of the material's ease of handling, superior strength-to-weight ratio and corrosion resistance. An experimental study involving 4 full scale universal beams was conducted in order to investigate the ability of CFRP to recover the strength and stiffness of beams following the introduction of web openings. All the specimens were tested under 6-point bending in the experiments. For further comparison, the equivalent test series without the addition of strengthening was modelled numerically via finite element analysis.. The effectiveness of the strengthening technique was demonstrated with increases in the load carrying capacity over the un-altered beam of between 5 and 20% being achieved

Bond behaviour of rebar in concrete at elevated temperatures:a soft computing approach

This paper assesses the capability of using a new data-driven approach to predict the bond strength between steel rebar and concrete subjected to high temperatures. The analysis has been conducted using a novel evolutionary polynomial regression analysis (EPR-MOGA) that employs soft computing techniques, and new correlations have been proposed. The proposed correlations provide better predictions and enhanced accuracy than existing approaches, such as classical regression analysis. Based on this novel approach, the resulting correlations have achieved a lower mean absolute error (𝑀𝐴𝐸), and root mean square error (𝑅𝑀𝑆𝐸), a mean (𝜇) close to the optimum value (1.0) and a higher coefficient of determination (R2) compared to available correlations, which use classical regression analysis. Based on their enhanced performance, the proposed correlations can be used to obtain better optimised and more robust design calculations

Boussinesq modelling of tsunami and storm wave impact

Many coastal protection structures in the UK have been designed for storm surges with appropriate return periods, but their performance during tsunami-type waves is uncertain. A shallow water and Boussinesq model is well suited to the investigation of both near-shore storm waves and tsunami waves. This paper makes use of the model to compare the effect on coastal structures of solitary waves and storm waves. Wave run-up parameters for both types of wave are generated and shown to be in good agreement with experimental data. The equations behind the model were derived assuming a small bed slope and therefore are not suitable for modelling waves interacting with vertical and near-vertical structures. However, the introduction of a reverse momentum term, to take account of a jet of water typical of a breaking wave impacting against a structure, allows wave overtopping volumes to be well predicted, although it had a minor effect on the forces acting on the structure. Comparisons with experimental data, for both solitary waves and storm waves, are presented. Using this model, the difference between the impact, in terms of wave forces and wave overtopping, of tsunami waves and storm waves for a given structure is investigated. </jats:p

Outdoor air pollution and near-fatal/fatal asthma attacks in children: A systematic review.

BACKGROUND: Globally, observational studies have demonstrated an association between high levels of air pollution and asthma attacks in children. It remains unclear whether and to what extent exposure may be associated with increased near-fatal/fatal attacks. OBJECTIVE: To systematically review the evidence for an association between ambient outdoor air pollution and fatal and/or near-fatal asthma (NFA). METHODS: Following Cochrane methodology, we searched MEDLINE, EMBASE, Web of Science, Scopus, and Open Grey electronic databases for studies reporting the association of fatal/NFA and air pollution (particulate matter [PM], sulfur dioxide, nitrogen dioxide, black carbon and ozone [O3 ]) in children. NFA was defined as requiring intensive care unit (ICU) management. RESULTS: Two reviewers independently screened 1358 papers. A total of 276 studies identified asthma attacks related to air pollution, 272 did not meet inclusion criteria after full-text review. Four observational studies described fatal/NFA, of which three addressed NFA. PM2.5 (per 12.5 µg/m3 increase) and O3 (per 22 ppb increase) were associated with NFA in one study (PM2.5, relative risk: 1.26, confidence interval [CI] [1.10-1.44]), O3  (1.19 [1.01-1.40]). PM10 was associated with ICU admission in the context of thunderstorm asthma. Elemental carbon was associated equally with NFA that did not require an ICU admission (p = 0.67). Studies of fatal asthma including children did not demarcate age within the analysis. CONCLUSIONS: Ozone and PM2.5 have been associated with NFA in children but synthesis is limited by the paucity of studies and methodological heterogeneity. Poor reporting of severities of asthma attacks hinders the assessment of whether outdoor air pollution is associated with an increased number of NFA/fatal attacks in children

Eddy Impacts on the Florida Current

The Gulf Stream in the Atlantic carries warm water northwards and forms both the return closure of the subtropical gyre as well as the upper limb of the meridional overturning circulation. Recent time series recorded east of the Bahamas at 26°N indicate that from May 2009 to April 2011, in contrast with past observations, the northward flowing Antilles Current covaried with the Gulf Stream in the Florida Straits—the Florida Current—even though the Florida and Antilles Currents are separated by banks and islands spanning 150?km. The peak-to-trough amplitude of transport variations during this period was 15?×?106?m3?s?1 for the Florida Current and 12?×?106?m3?s?1 for the Antilles Current, at time scales of 50?days to a year. From satellite observations, we show that the fluctuations in both the Florida and Antilles Currents between May 2009 and April 2011 are driven by eddy activity east of the Bahamas. Since the Florida Current time series is a critical time series for the state of the oceans, and often compared to climate models, this newly identified source of variability needs careful consideration when attributing the variability of the Florida Current to changes in the larger-scale circulations (e.g., gyre and overturning) or wind forcing.<br/

NGC 5775: Anatomy of a disk-halo interface

We present the first high-resolution study of the disk-halo interface in an edge-on galaxy (NGC 5775) in which every component of the interstellar medium is represented and resolved (though not all to the same resolution). New single-dish CO J=2-1 and CO J=1-0 data, ROSAT X-ray data, and HIRES IRAS data are presented along with HI data which emphasizes the high latitude features. In conjunction with previously published radio continuum (6 and 20 cm) and H data, we find spatial correlations between various ISM components in that all components of the ISM are present in the disk-halo features (except for CO for which there is insufficient spatial coverage). The HI features extend to ~7 kpc above the plane, form loops in position-position space, in one case, form a loop in position-velocity space, and are also observed over a large velocity range. This implies that the disk-halo features represent expanding supershells. However, the shells may be incomplete and partially open-topped, suggesting that we are observing the breakup of the supershells as they traverse the disk-halo interface. There is some evidence for acceleration with z and both redshifted and blueshifted velocities are present, although the gas which is lagging with respect to galactic rotation dominates. The radio continuum spectral index is flatter around the shell rims and we show that this cannot be due to a contribution from thermal gas but rather is due to intrinsic flattening of the non-thermal spectral index, suggesting that shocks may be important in these regions. The H emission is located interior to the HI. For feature F3, the H emission forms the interior skin of the HI shell, yet there appears to be a minimum of in-disk star formation immediately below the feature. We present a picture of a typical HI supershell which accelerates and breaks up through the disk-halo interface. Such a feature is likely internally generated via an energetic event in the disk

GIS-based assessment of groundwater quality for drinking and irrigation purposes in central Iraq

In many parts of the world, groundwater is considered to be a key source of fresh water for both the domestic and non-domestic sectors. Where groundwater extraction is implemented, systems to monitor water quality must ensure a safe and sustainable supply. Over the years, Iraq has suffered from surface water quality and supply problems, necessitating groundwater extraction in many regions. This study investigates groundwater quality in a region of central Iraq around Babylon city, covering an area of 5119 km2. The data gathered for this study included maps, well locations and water quality data and was sourced from the relevant governmental departments. A base map of the focussed region was initially prepared following data collection. The analysed water quality parameters were used as an attribute database to produce thematic maps using a geographical information system (GIS) environment. In this paper, the water quality index (WQI) and the irrigation water quality index (IWQI) were calculated for different groundwater samples using various parameters including the Electrical Conductivity (EC), Cl−, HCO3−, Na+ and pH. Moreover, the groundwater suitability for irrigation purposes has been assessed using indices such as Kelly’s ratio (KR), sodium absorption ratio (SAR), residual sodium carbonate (RSC), soluble sodium percentage (SSP) and permeability index (PI). Water quality index maps have been developed using the GIS environment. The obtained results reveal that the groundwater in the study location requires specific treatments to be usable

XMM-EPIC observation of MCG-6-30-15: Direct evidence for the extraction of energy from aspinning black hole?

We present XMM-Newton European Photon Imaging Camera (EPIC) observations of the bright Seyfert 1 galaxy MCG-6-30-15, focusing on the broad Fe K$\alpha$ line at ~6keV and the associated reflection continuum, which is believed to originate from the inner accretion disk. We find these reflection features to be extremely broad and red-shifted, indicating its origin from the very most central regions of the accretion disk. It seems likely that we have caught this source in the ``deep minimum'' state first observed by Iwasawa et al. (1996). The implied central concentration of X-ray illumination is difficult to understand in any pure accretion disk model. We suggest that we are witnessing the extraction and dissipation of rotational energy from a spinning black hole by magnetic fields connecting the black hole or plunging region to the disk.Comment: 6 pages and one postscript figure. Accepted for publication in MNRAS letter