72 resultados para Lithographic Technical Forum


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Like many long-lived composers, Vaughan Williams suffered a decline in his reputation immediately following his death, as the emergence in the 1960s of a younger generation of composers rendered much of his work outmoded in the eyes of many critics. In recent years, however, the reception of Vaughan Williams's music among composers has improved markedly, a combination of the ebbing of the tide of high modernism and greater pluralism in contemporary music, and a growing awareness that Vaughan Williams was perhaps more modernist (or at least progressive) than had previously been thought. In interviews with four leading British composers (two of whom were part of the 1960s generation mentioned above), I investigate the nature and extent of Vaughan Williams's legacy to his successors, both musical and social. What emerges is a near consensus on Vaughan Williams's greatest works, but a diversity of views on his compositional techniques and on his place among his European contemporaries.

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In contrast to most empirical investigations of the efficiency of multiproduct financial institutions, which either estimate scale and scope economies with a given state of technology, or only analyse technical change in the presence of overall scale economies, this study estimates overall scale economies, product-specific scale economies and scope economies in the presence of both neutral and non-neutral technical change. Also, in contrast to most other empirical studies in this area, standard errors are computed for all relevant statistics. The findings indicate diseconomies of scope; overall diseconomies of scale; product-specific economies are decreasing for investments and increasing for loans; in addition to substantial neutral technical change, biased technical change is labour- and capital-saving and deposits-using in character.

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Numerous methods are available to measure the permeation properties of concrete, which can be classified in terms of the diffusion, absorption and permeability properties. The results from these tests are generally used to infer 'quality' or relative durability. Some of these tests involve the laboratory assessment of a sample of concrete extracted from the structure. However, this Technical Note concentrates on the alternative methods appropriate for use on site. Guidance is given on the choice of an appropriate test method, which in most practical situations depends on the predominant mechanism acting on the concrete under consideration.

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Turbocompounding is the process of recovering a proportion of an engine’s fuel energy that would otherwise be lost in the exhaust process and adding it to the output power. This was first seen in the 1930s and is carried out by coupling an exhaust gas turbine to the crankshaft of a reciprocating engine. It has since been recognised that coupling the power turbine to an electrical generator instead of the crankshaft has the potential to reduce the fuel consumption further with the added flexibility of being able to decide how this recovered energy is used. The electricity generated can be used in automotive applications to assist the crankshaft using a flywheel motor generator or to power ancillaries that would otherwise have run off the crankshaft. In the case of stationary power plants, it can assist the electrical power output. Decoupling the power turbine from the crankshaft and coupling it to a generator allows the power electronics to control the turbine speed independently in order to optimise the specific fuel consumption for different engine operating conditions. This method of energy recapture is termed ‘turbogenerating’.

This paper gives a brief history of turbocompounding and its thermodynamic merits. It then moves on to give an account of the validation of a turbogenerated engine model. The model is then used to investigate what needs to be done to an engine when a turbogenerator is installed. The engine being modelled is used for stationary power generation and is fuelled by an induced biogas with a small portion of palm oil being injected into the cylinder to initiate combustion by compression ignition. From these investigations, optimum settings were found that result in a 10.90% improvement in overall efficiency. These savings relate to the same engine without a turbogenerator installed operating with fixed fuelling.

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Over the last decade there has been a rapid global increase in wind power stimulated by energy and climate policies. However, as wind power is inherently variable and stochastic over a range of time scales, additional system balancing is required to ensure system reliability and stability. This paper reviews the technical, policy and market challenges to achieving ambitious wind power penetration targets in Ireland’s All-Island Grid and examines a number of measures proposed to address these challenges. Current government policy in Ireland is to address these challenges with additional grid reinforcement, interconnection and open-cycle gas plant. More recently smart grid combined with demand side management and electric vehicles have also been presented as options to mitigate the variability of wind power. In addition, the transmission system operators have developed wind farm specific grid codes requiring improved turbine controls and wind power forecasting techniques.