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11.
In this paper it is argued that the re-establishment of a metropolitan government in the Greater Copenhagen Area in 2000 (Greater
Copenhagen Authority) is not to be seen as a return to the kind of regional, coordinative authority (Greater Copenhagen Council)
that was abolished in the Thatcherite climate of the 1980s. Throughout the 1980s and 1990s new forms of urban governance,
entrepreneurialism and a higher national priority to the capital region were introduced, which changed the conditions under
which the new metropolitan government is operating. This `contextualization' of the analysis of the two generations of metropolitan
government points to the fact that typologies of metropolitan government, such as the one put forward by Sharpe (1995), often
lacks analytical cogency.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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L. Kristensen C. E. Andersen H. E. Jørgensen P. Kirkegaard K. Pilegaard 《Journal of Atmospheric Chemistry》1997,27(3):249-269
We have discussed the behavior of a non-conserved scalar in the stationary, horizontally homogeneous, neutral surface-flux layer and, on the basis of conventional second-order closure, derived analytic expressions for flux and for mean concentration of a gas, subjected to a first-order removal process. The analytic flux solution showed a clear deviation from the constant flux, characterizing a conserved scalar in the surface-flux layer. It decreases with height and is reduced by an order of magnitude of the surface flux at a height equal to about the typical mean distance a molecule can travel before destruction. The predicted mean concentration profile, however, shows only a small deviation from the logarithmic behavior of a conserved scalar. The solution is consistent with assuming a flux-gradient relationship with a turbulent diffusivity corrected by the Damköhler ratio, the ratio of a characteristic turbulent time scale and the scalar mean lifetime. We show that if we use only first-order closure and neglect the effect of the Damköhler ratio on the turbulent diffusivity we obtain another analytic solution for the profiles of the flux and the mean concentration which, from an experimental point of view, is indistinguishable from the first analytic solution. We have discussed two cases where the model should apply, namely NO which, by night, is irreversibly destroyed by interaction with mainly O3 and the radioactive 220Rn. Only in the last case was it possible to find data to shed light on the validity of our predictions. The agreement seemed such that a falsification of our model was impossible. It is shown how the model can be used to predict the surface flux of 220Rn from measured concentration profiles. 相似文献
15.
Reduction of ground vibration by means of barriers or soil improvement along a railway track 总被引:3,自引:0,他引:3
Trains running in built-up areas are a source to ground-borne noise. A careful design of the track may be one way of minimizing the vibrations in the surroundings. For example, open or infilled trenches may be constructed along the track, or the soil underneath the track may be improved. In this work, the influence of the track design and properties on the level of ground vibration due to a vehicle moving with subsonic speed is examined. A coupled finite element-boundary element model of the track and subsoil is employed, adopting a formulation in the moving frame of reference following the vehicle. The computations are carried out in the frequency domain for various combinations of the vehicle speed and the excitation frequency. The analyses indicate that open trenches are more efficient than infilled trenches or soil stiffening–even at low frequencies. However, the direction of the load is of paramount importance. For example, the response outside a shallow open trench may change dramatically when horizontal load is applied instead of vertical load. 相似文献
16.
Improved spatial delineation of streambed properties and water fluxes using distributed temperature sensing
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Landon J. S. Halloran Hamid Roshan Gabriel C. Rau Martin S. Andersen R. Ian Acworth 《水文研究》2016,30(15):2686-2702
A new method was developed for analysing and delineating streambed water fluxes, flow conditions and hydraulic properties using coiled fibre‐optic distributed temperature sensing or closely spaced discrete temperature sensors. This method allows for a thorough treatment of the spatial information embedded in temperature data by creating a matrix visualization of all possible sensor pairs. Application of the method to a 5‐day field dataset reveals the complexity of shallow streambed thermal regimes. To understand how velocity estimates are affected by violations of assumptions of one‐dimensional, saturated, homogeneous flow and to aid in the interpretation of field observations, the method was also applied to temperature data generated by numerical models of common field conditions: horizontal layering, presence of lateral flow and variable streambed saturation. The results show that each condition creates a distinct signature visible in the triangular matrices. The matrices are used to perform a comparison of the behaviour of one‐dimensional analytical heat‐tracing models. The results show that the amplitude ratio‐based method of velocity calculation leads to the most reliable estimates. The minimum sensor spacing required to obtain reliable velocity estimates with discrete sensors is also investigated using field data. The developed method will aid future heat‐tracing studies by providing a technique for visualizing and comparing results from fibre‐optic distributed temperature sensing installations and testing the robustness of analytical heat‐tracing models. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
17.
Mineralogy and Petrology - Rift related magmatism during Permian time in the northern margin of Indian plate is represented by basic dykes in several Himalayan terranes including north western... 相似文献
18.
Jana
lavsdttir Martyn S. Stoker Lars O. Boldreel Morten Sparre Andersen
luva R. Eidesgaard 《Basin Research》2019,31(5):841-865
Lower Palaeogene extrusive igneous rocks of the Faroe Islands Basalt Group (FIBG) dominate the Faroese continental margin, with flood basalts created at the time of breakup and separation from East Greenland extending eastwards into the Faroe‐Shetland Basin. This volcanic succession was emplaced in connection with the opening of the NE Atlantic; however, consensus on the age and duration of volcanism remains lacking. On the Faroe Islands, the FIBG comprises four main basaltic formations (the pre‐breakup Lopra and Beinisvørð formations, and the syn‐breakup Malinstindur and Enni formations) locally separated by thin intrabasaltic sedimentary and/or volcaniclastic units. Offshore, the distribution of these formations remains ambiguous. We examine the stratigraphic framework of these rocks on the Faroese continental margin combining onshore (published) outcrop information with offshore seismic‐reflection and well data. Our results indicate that on seismic‐reflection profiles, the FIBG can be informally divided into lower and upper seismic‐stratigraphic packages separated by the strongly reflective A‐horizon. The Lower FIBG comprises the Lopra and Beinisvørð formations; the upper FIBG includes the Malinstindur and Enni formations. The strongly reflecting A‐horizon is a consequence of the contrast in properties of the overlying Malinstindur and underlying Beinisvørð formations. Onshore, the A‐horizon is an erosional surface, locally cutting down into the Beinisvørð Formation; offshore, we have correlated the A‐horizon with the Flett unconformity, a highly incised, subaerial unconformity, within the juxtaposed and interbedded sedimentary fill of the Faroe‐Shetland Basin. We refer to this key regional boundary as the A‐horizon/Flett unconformity. The formation of this unconformity represents the transition from the pre‐breakup to the syn‐breakup phase of ocean margin development in the Faroe–Shetland region. We examine the wider implications of this correlation considering existing stratigraphic models for the FIBG, discussing potential sources of uncertainty in the correlation of the lower Palaeogene succession across the Faroe–Shetland region, and implications for the age and duration of the volcanism. 相似文献
19.
This paper analyses the extent to which specialisation gains can be achieved by liberalising access to fishing quotas within the European Union (EU). Fishing quotas are today exchanged between EU member states at a rate of 4% of total turnover in EU fisheries. Germany, Belgium, Denmark and the Netherlands are the most active. Only one fourth of these exchanges are permanent. With the management systems in EU fisheries differing among countries, comparative advantages in fisheries exist in member states with the best management practices. Hence, although positive but small specialisation gains exist in EU fisheries today, these gains might potentially be increased by liberalising access to fishing quotas and allowing transferability of quotas between individuals from different countries on a permanent basis. Increasing the gains might, however, affect relative stability. 相似文献
20.
The trapped fluid phase in upper mantle xenoliths from Victoria,Australia: implications for mantle metasomatism 总被引:5,自引:0,他引:5
T. Andersen Suzanne Y. O'Reilly W. L. Griffin 《Contributions to Mineralogy and Petrology》1984,88(1-2):72-85
Mantle-derived xenoliths of spinel lherzolite, spinel pyroxenite, garnet pyroxenite and wehrlite from Bullenmerri and Gnotuk maars, southwestern Victoria, Australia contain up to 3 vol.% of fluids trapped at high pressures. The fluid-filled cavities range in size from fluid inclusions (1–100 m) up to vugs 11/2 cm across, lined with euhedral high-pressure phases. The larger cavities form an integral part of the mosaic microstructure. Microthermometry and Raman laser microprobe analysis show that the fluids are dominantly CO2. Small isolated inclusions may have densities 1.19 g/cm3, but most inclusions show microstructural evidence of partial decrepitation during eruption, and these have lower fluid densities. Mass-spectrometric analysis of gases released by crushing or heating shows the presence of He, N2, Ar, H2S, COs and SO2 in small quantities; these may explain the small freezing-point depressions observed in some inclusions. Petrographic, SEM and microprobe studies show that the trapped fluids have reacted with the cavity walls (in clinopyroxene grains) to produce secondary amphiboles and carbonates. The trapped CO2 thus represents only a small residual proportion of an original volatile phase, which has undergone at least two stages of modification — first by equilibration with spinel lherzolite to form amphibole (±mica±apatite), then by limited reaction with the walls of the fluid inclusions. The inferred original fluid was a CO2-H2O mixture, with significant contents of (at least) Cl and sulfur species. Generation of this fluid phase in the garnet-peridotite stability field, followed by its migration to the spinel peridotite stability field, would provide an efficient mechanism for metasomatic enrichment of the upper mantle in LIL elements. This migration could involve either a volatile flux or transport in small volumes of silicate melt that crystallize in the spinel peridotite field. These observations suggest that some portions of the subcontinental upper mantle contain large reservoirs of free fluid CO2, which may be liberated during episodes of rifting or magmatism, to induce granulite-facies metamorphism of the lower crust. 相似文献