Determining Propeller Erosion at the Stern of a Berthing Ship

This paper presents the findings from an experimental investigation in to the nature and extent of the scouring that occurs when a ship berths in front of a perpendicular quay wall within the confines of a harbor. It examines the interaction between the relative position of the quay wall to the central axis of the ship and the influence of angle of the vessel's rudder on the magnitude of the scouring produced. The experimental programme covered a range of sediment sizes, propeller diameters and speeds of rotation and rudder angles. Also, methods for calculating the depth of expected scour are presented in terms of initial semi-empirical equations for the data range under investigation.

Abatement technologies for road surface run-off

Heavy metals, primarily zinc, copper, lead, and chromium, and Polycyclic Aromatic Hydrocarbons (PAHs) are the main hazardous constituents of road runoff. The main sources of these contaminants are vehicle emission, mostly through wear and leakage, although erosion of the road surface and de-icing salts are also recognised pollution sources. The bioavailability of these toxic compounds, and more importantly their potential biomagnification along food chains, could affect aquatic communities persistently exposed to road runoff. Several internationally approved abatement technologies are available for the management of road runoff on new motorway schemes. Recent studies conducted in Cork and Dublin, Ireland demonstrated the efficacy of infiltration trenches as abatement technologies in the removal of both heavy metals and PAHs prior to discharge; the technology was however inefficient in mitigating first flush events. Gully traps with sedimentation chambers, another technology investigated, demonstrated to have a substantially lower removal potential but appeared to be more effective in attenuating surges of contaminants attributed to first flush events. Consequently the employment of combined abatement techniques could efficiently minimise deviations from required effluent concentrations. The studies determined a relatively stationary accumulation of heavy metals and PAHs in sediments close to the point of discharge with a rapid decline in concentration in nearby downstream sediments (<50m). Further, Microtox® Solid Phase testing reported a negligible impact on assemblages exposed to contaminated sediments for all sites investigated. This paper describes pollutant loading from road runoff and mitigation measures from a freshwater deterioration in a water quality perspective. The results and analysis of field samples collected adjacent to a number of roads and motorways in Ireland is also presented. Finally sustainable drainage systems, abatement techniques and technologies available for onsite treatment of runoff are presented to improve and mitigate impacts of vehicular transport on the environment.

Coxiella buvnetii infection of an aortic graft with multiple vertebral body erosion

Q fever is caused by Coxiella burnetii and often has an insidious clinical presentation. We describe a rare case of Q fever infection of an aortic graft presenting with pyrexia and constant severe midlumbar pain due to erosion of multiple vertebral bodies. After successful treatment with graft resection and extra-anatomic vascular reconstruction, the patient continues on lifelong antibiotic therapy. We also present regional Q fever epidemiologic data together with a review of all previously documented cases of Q fever infections of vascular prostheses.

Determining propeller induced erosion alongside quay walls in harbours using Artificial Neural Networks

In shallow waters, such as those found close to berth structures, the wash from a manoeuvring ship’s propeller can cause erosion of the seabed. This erosion can be increased if the wash intersects a berth structure. A number of researchers have undertaken model studies and used regression analysis to develop predictive relationships for the scouring action. This paper presents an experimental investigation with Artificial Neural Networks (ANN’s), used to analyse the results. The purpose of using ANN’s was to examine the prediction accuracy of the Networks in comparison with previous regression analysis methods. ANN’s were found to provide a more accurate method of predicting propeller wash scour than the equations presented by previous investigators.

Combination of CFD and DOE to analyse solid particle erosion in elbows

Solid particle erosion is a major concern in the engineering industry, particularly where transport of slurry flow is involved. Such flow regimes are characteristic of those in alumina refinement plants. The entrainment of particulate matter, for example sand, in the Bayer liquor can cause severe erosion in pipe fittings, especially in those which redirect the flow. The considerable costs involved in the maintenance and replacement of these eroded components led to an interest in research into erosion prediction by numerical methods at Rusal Aughinish alumina refinery, Limerick, Ireland, and the University of Limerick. The first stage of this study focused on the use of computational fluid dynamics (CFD) to simulate solid particle erosion in elbows. Subsequently an analysis of the factors that affect erosion of elbows was performed using design of experiments (DOE) techniques. Combining CFD with DOE harnesses the computational power of CFD in the most efficient manner for prediction of elbow erosion. An analysis of the factors that affect the erosion of elbows was undertaken with the intention of producing an erosion prediction model. © 2009 Taylor & Francis.

Dental erosion among 12-14 year old school children in Khartoum:A pilot study

Objectives: To investigate dental erosion among 12-14 year old Sudanese school children and evaluate the associated risk factors. Basic Research Design: Cross sectional survey in secondary schools in Khartoum city, Sudan. Method and Participants: A sample of 157 school children was obtained from both private and public schools. Erosion on the labial and palatal surfaces of maxillary incisors was measured by criterion based on the Smith and Knight Tooth Wear Index. Dietary intake and other related factors were assessed using a questionnaire. Results: The overall erosion prevalence in this group was 66.9%, of which 45.2% was mild and 21.7% was moderate erosion. A strong association was found between erosion and private schooling (higher socioeconomic groups), carbonated drinks, herbal hibiscus drink and traditional acidic food consumption. Conclusion: There was a high prevalence of dental erosion among Sudanese school children which was mild to moderate in severity and was strongly associated with acidic dietary intake © BASCD 2007.

Restrospective genetic monitoring of the threatened Yellow marsh saxifrage (Saxifraga hirculus) reveals genetic erosion but provides valuable information for conservation strategies

Aim: Retrospective genetic monitoring, comparing genetic diversity of extant populations with historical samples, can provide valuable and often unique insights into evolutionary processes informing conservation strategies. The Yellow marsh saxifrage (Saxifraga hirculus) is listed as ‘critically endangered’ in Ireland with only two extant populations. We quantified genetic changes over time and identified genotypes in extant populations that could be used as founders for reintroductions to sites where the species is extinct.

Location: Ireland.

Methods: Samples were obtained from both locations where the species is currently found, including the most threatened site at the Garron Plateau, Co. Antrim, which held only 13 individuals during 2011. Herbarium samples covering the period from 1886 to 1957 were obtained including plants from the same area as the most threatened population, as well as three extinct populations. In total, 422 individuals (319 present-day and 103 historical) were genotyped at six microsatellite loci. Species distribution modelling was used to identify areas of potentially suitable habitat for reintroductions.

Results: Level of phenotypic diversity within the most threatened population was significantly lower in the present-day compared with historical samples but levels of observed heterozygosity and number of alleles, whilst reduced, did not differ significantly. However, Bayesian clustering analysis suggested gradual lineage replacement over time. All three measures of genetic diversity were generally lower at the most threatened population compared with the more substantial extant populations in Co. Mayo. Species distribution modelling suggested that habitat at one site where the species is extinct may be suitable for reintroduction.

Main conclusions: The dominant genetic lineage in the most threatened population is rare elsewhere; thus, care needs to be taken when formulating any potential reintroduction programme. Our findings highlight both the need for genetic monitoring of threatened populations, but also for its swift implementation before levels of diversity become critically low.