121 resultados para projectile technologies
Resumo:
The flowfield around a supersonic projectile using a pin actuator control method has been predicted using computational fluid dynamics. It has been predicted using both viscous and inviscid methods for a number of positions. Both methods showed that an optimal longitudinal position exists. However, the inviscid model over-predicted the lateral acceleration due to the difference in shock formation around the pin between the two approaches. The optimal location was predicted independent of solver, however the higher-fidelity solver predicted lower achievable lateral accelerations. This is due to the viscous interactions caused by the pin. The effect of projectile orientation has shown that shielding the pin leads to reduced effectiveness due to the wake of the fin enveloping the pin. When the pin is exposed to onset flow, the forces achieved are increased. There is also an increase in the achievable forces and moments with increasing Mach number.
Resumo:
This is a major review work on ground water remediation since the earlier work of Mulligan et al published in 2001 in Engineering Geology Journal. This work resulted from the joint research project of QUB and University of Malaya on iron removal from groundwater for public water supply.
Resumo:
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.
Resumo:
The growth of renewable power sources, distributed generation and the potential for alternative fuelled modes of transport such as electric vehicles has led to concerns over the ability of existing grid systems to facilitate such diverse portfolio mixes in already congested power systems. Internationally the growth in renewable energy sources is driven by government policy targets associated with the uncertainties of fossil fuel supplies, environmental issues and a move towards energy independence. Power grids were traditionally designed as vertically integrated centrally managed entities with fully dispatchable generating plant. Renewable power sources, distributed generation and alternative fuelled vehicles will place these power systems under additional stresses and strains due to their different operational characteristics. Energy storage and smart grid technologies are widely proposed as the tools to integrate these future diverse portfolio mixes within the more conventional power systems. The choice in these technologies is determined not only by their location on the grid system, but by the diversification in the power portfolio mix, the electricity market and the operational demands. This paper presents a high level technical and economic overview of the role and relevance of electrical energy storage and smart grid technologies in the next generation of renewable power systems.