Limits to transparency exploring conceptual and operational aspects of the ICES framework for providing precautionary fisheries management advice     

Hauge  Kjellrun Hiis; Nielsen  Kare Nolde; Korsbrekke  Knut 《ICES Journal of Marine Science》2007,64(4):738-743

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Prevention of oil spill from shipping by modelling of dynamic risk   总被引：1，自引：0，他引：1  

Eide MS  Endresen O  Breivik O  Brude OW  Ellingsen IH  Røang K  Hauge J  Brett PO 《Marine pollution bulletin》2007,54(10):1619-1633

This paper presents a new dynamic environmental risk model, with intended use within a new, dynamical approach for risk based ship traffic prioritisation. The philosophy behind this newly developed approach is that shipping risk can be reduced by directing efforts towards ships and areas that have been identified as high priority (high risk), prior to a potential accident. The risk model proposed in this paper separates itself from previous models by drawing on available information on dynamic factors and by focusing on the ship's surroundings. The model estimates the environmental risk of drift grounding accidents for oil tankers in real time and in forecast mode, combining the probability of grounding with oil spill impact on the coastline. Results show that the inherent dynamic risk introduced by an oil tanker sailing along the North Norwegian coast depends, not surprisingly, significantly upon wind and ocean currents, as well as tug position and cargo oil type. Results of this study indicate that the risk model is well suited for real time risk assessment, and effectively separates low risk and high risk situations. The model is well suited as a tool to prioritise oil tankers and coastal segments. This enables dynamic risk based positioning of tugs, using both real-time and projected risk, for effective support in case of a drifting ship situation.  相似文献   

GPS relative positioning at a precision level of one part per billion     

P. H. Andersen  S. Hauge  O. Kristiansen 《Journal of Geodesy》1993,67(2):91-106

Six days of data from the GIG'91 experiment have been analyzed with a fiducial strategy. The results obtained with our orbital software GEOSAT, show daily horizontal and length repeatabilities at the level of 1 part in 10⁹ plus 2 mm for baseline lengths up to 4000 km. A direct comparison with results from the GIPSY software shows, with some exceptions, mean differences at the sub-cm level. After transformation to ITRF'90 the rms of the coordinate differences is 14.8 mm. Studies of orbital predictions and comparisons with external high precision orbits indicate a mean orbit precision and accuracy of around 35 cm in each cartesian coordinate. Correlations between the GEOSAT and GIPSY solutions indicate some common model deficiencies.  相似文献   

Modeling of Fluvial Reservoirs with Object Models   总被引：16，自引：0，他引：16  

L. Holden  R. Hauge  Ø. Skare  A. Skorstad 《Mathematical Geology》1998,30(5):473-496

An object model for fluvial reservoirs that has been developed from 1985 to present is described. It uses a formal mathematical object model (marked point process) describing the distributions of four facies: channel, crevasse, barrier, and background. Realisations from the model are generated using the Metropolis-Hastings simulation algorithm with simulated annealing conditioning on the volume ratios and well observations. The main challenge has been to find a suitable parameterization of the geology of fluvial reservoirs, and to find and implement the generating function of the channels in the simulation algorithm. The model and simulation algorithm can be conditioned on arbitrary well paths including horizontal wells and paths with partly missing observations, well test data, well contacts, seismic data, and general geological knowledge.  相似文献   

Discussion on the classification of fine structures in continua     

Ø. Elgarøy 《Solar physics》1986,104(1):41-42

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Object Models with Vector Steering     

Ragnar Hauge  Anne Randi Syversveen  Alister Macdonald 《Mathematical Geology》2006,38(1):17-32

Object models are widely used to model the distribution of facies in a reservoir. Several computer programs exist for modelling fluvial channels or more general facies objects. This paper focuses on a marked point model with objects that are able to orient locally according to a vector field. In this way, objects with locally varying curvature are created. With this kind of objects it is possible to model complex depositional basins, that are not easily modelled with conventional methods. The new object type is called Backbone objects. The objects have a piecewise linear centerline and are able to follow the direction of a three-dimensional vector field locally in lateral and vertical direction. How well the objects follow the vector field is determined by three parameters. Use of different coordinate systems and mapping between the systems make it possible to generate Gaussian random fields that follow the shape and direction of the objects. The Gaussian fields can be used to model petrophysical variables, which is important for fluid flow modelling.  相似文献   

Solar isotopic composition and abundance of europium     

Øivind Hauge 《Solar physics》1972,27(2):286-293

High resolution spectra of six photospheric Eu ii lines have been studied using the method of spectrum synthesizing. The isotope ratio is found to be Eu₁₅₃/Eu₁₅₁ = (48 ± 6)/(52 6) and the solar abundance of europium equals log _Eu = 0.7 ± 0.2 in the log _H = 12.00 scale.  相似文献   

Viscous inflationary universe models     

Ø. Grøn 《Astrophysics and Space Science》1990,173(2):191-225

The research on viscous cosmological models is reviewed and carried further. Inflationary cosmological models of Bianchi type-I with shear, bulk, and nonlinear viscosity are studied. The inflation field energy is represented by a two-components cosmic fluid consisting of a vacuum fluid and a Zel'dovich fluid. It is shown that there exist models in which the viscous Zel'dovich fluid removes the initial singularity of the corresponding viscosity free models. The mean expansion of a Zel'dovich dominated unvierse is found to be independent of shear viscosity and anisotropy. Bulk viscosity and shear viscosity cause exponential decay of anisotropy, while nonlinear viscosity causes power-law decay of anisotropy.  相似文献   

The Role of Groundwater for Lake‐Water Quality and Quantification of N Seepage          下载免费PDF全文

Jacob Kidmose  Peter Engesgaard  Daniela A. Oliveira Ommen  Bertel Nilsson  Mogens R. Flindt  Frede Ø. Andersen 《Ground water》2015,53(5):709-721

The heterogeneous nature of both groundwater discharge to a lake (inflow) and nitrate concentrations in groundwater can lead to significant errors in calculations of nutrient loading. Therefore, an integrated approach, combining groundwater flow and transport modelling with observed nitrate and ammonium groundwater concentrations, was used to estimate nitrate loading from a catchment via groundwater to an oligotrophic flow‐through lake (Lake Hampen, Denmark). The transport model was calibrated against three vertical nitrate profiles from multi‐level wells and 17 shallow wells bordering a crop field near the lake. Nitrate concentrations in groundwater discharging to the lake from the crop field were on average 70 times higher than in groundwater from forested areas. The crop field was responsible for 96% of the total nitrate loading (16.2 t NO₃/year) to the lake even though the field only covered 4.5% of the catchment area. Consequently, a small change in land use in the catchment will have a large effect on the lake nutrient balance and possible lake restoration. The study is the first known attempt to estimate the decrease of nitrate loading via groundwater to a seepage lake when an identified catchment source (a crop field) is removed.  相似文献   

Precise ERS-1 orbit calculation     

P. H. Andersen  K. Aksnes  S. Hauge 《Journal of Geodesy》1995,69(4):192-199

This analysis was performed with the GEOSAT software developed at NDRE for high-precision analysis of satellite tracking and VLBI data for geodetic and geodynamic applications.For applications to ERS-1, a realistic surface force model is used together with the Jacchia 77 atmospheric model, semi-daily drag coefficients, a 1-cpr sinusoidal along-track acceleration, and the GSFC JGM-2 gravity model. ERS-1 orbits have been derived for 5.5-day arcs of laser tracking data between July 6 and August 12, 1992. Results from overlapping orbits and comparison with precise D-PAF orbits indicate an orbital accuracy of 10–15 cm in the radial direction, ~ 60 cm in the along-track direction and ~ 15 cm in the cross-track direction.  相似文献