Cl/Br of scapolite as a fluid tracer in the earth's crust: insights into fluid sources in the Mary Kathleen Fold Belt,Mt. Isa Inlier,Australia     

J. Hammerli  C. Spandler  N. H. S. Oliver  B. Rusk 《Journal of Metamorphic Geology》2014,32(1):93-112

A combination of analytical methods, including trace element analysis of Br in scapolite by LA‐ICP‐MS, was employed to unravel the fluid–rock interaction history of the Mary Kathleen Fold Belt of northern Australia. Halogen ratios in the metamorphic and hydrothermally derived scapolite from a range of rock‐types record interaction between the host rocks and magmatic‐hydrothermal fluids derived from granite plutons and regional metamorphism. The results show that halite‐dissolution supplied at best only minor chlorine to fluids in the Fold Belt. Chlorine/bromine ratios in metamorphic scapolite indicate that fluids were dominantly derived from basinal brines formed from sub‐aerial evaporation of seawater beyond the point of halite saturation. This bittern fluid infiltrated the underlying sedimentary sequences prior to regional metamorphism. Zoned scapolite in a major late metamorphic mineralized shear‐zone records three discrete pulses of magmatic and metamorphic fluid, and it is suggested that fluid mixing may have assisted mineralization along and around this shear‐zone. As a crucial prerequisite for halogen fluid tracer studies using scapolite, we find in our samples that Cl and Br do not fractionate when incorporated in scapolite. Furthermore, unaltered rims of heavily retrogressed scapolite show indistinguishable Cl/Br signatures compared with fresh grains from the same sample indicating retrograde metamorphism did not significantly affect Cl and Br signatures in scapolite group minerals.  相似文献   

Short-term periodicities in sunspot areas during solar cycle 22     

R. Oliver  J. L. Ballester 《Solar physics》1995,156(1):145-155

We have analyzed the daily record of sunspot areas during the current cycle 22 looking for the short-term periodicity of around 155 days which was present during some previous solar cycles. Two different methods have been used to compute the power spectra and the results indicate that such periodicity has been absent during the current solar cycle, which confirms the results obtained by other authors who used flares or flare-related data.However, we have found that, during some intervals of time, a periodicity close to 86 days is statistically significant. A similar periodicity was found by Landscheit (1986) in energetic X-ray flares, between 1970 and 1982 (second and first half of solar cycles 20 and 21, respectively), and by Bai (1992b) for important solar flares during solar cycle 20.  相似文献   

Application of the EnKF and Localization to Automatic History Matching of Facies Distribution and Production Data   总被引：3，自引：3，他引：0  

Chinedu C. Agbalaka  Dean S. Oliver 《Mathematical Geosciences》2008,40(4):353-374

The performance of the ensemble Kalman filter (EnKF) for continuous updating of facies location and boundaries in a reservoir model based on production and facies data for a 3D synthetic problem is presented. The occurrence of the different facies types is treated as a random process and the initial distribution was obtained by truncating a bi-Gaussian random field. Because facies data are highly non-Gaussian, re-parameterization was necessary in order to use the EnKF algorithm for data assimilation; two Gaussian random fields are updated in lieu of the static facies parameters. The problem of history matching applied to facies is difficult due to (1) constraints to facies observations at wells are occasionally violated when productions data are assimilated; (2) excessive reduction of variance seems to be a bigger problem with facies than with Gaussian random permeability and porosity fields; and (3) the relationship between facies variables and data is so highly non-linear that the final facies field does not always honor early production data well. Consequently three issues are investigated in this work. Is it possible to iteratively enforce facies constraints when updates due to production data have caused them to be violated? Can localization of adjustments be used for facies to prevent collapse of the variance during the data-assimilation period? Is a forecast from the final state better than a forecast from time zero using the final parameter fields?To investigate these issues, a 3D reservoir simulation model is coupled with the EnKF technique for data assimilation. One approach to enforcing the facies constraint is continuous iteration on all available data, which may lead to inconsistent model states, incorrect weighting of the production data and incorrect adjustment of the state vector. A sequential EnKF where the dynamic and static data are assimilated sequentially is presented and this approach seems to have solved the highlighted problems above. When the ensemble size is small compared to the number of independent data, the localized adjustment of the state vector is a very important technique that may be used to mitigate loss of rank in the ensemble. Implementing a distance-based localization of the facies adjustment appears to mitigate the problem of variance deficiency in the ensembles by ensuring that sufficient variability in the ensemble is maintained throughout the data assimilation period. Finally, when data are assimilated without localization, the prediction results appear to be independent of the starting point. When localization is applied, it is better to predict from the start using the final parameter field rather than continue from the final state.  相似文献   

Galileo status: orbits,clocks, and positioning   总被引：3，自引：1，他引：2  

Peter Steigenberger  Oliver Montenbruck 《GPS Solutions》2017,21(2):319-331

The European Global Navigation Satellite System Galileo is close to declaration of initial services. The current constellation comprises a total of 12 active satellites, four of them belonging to the first generation of In-Orbit Validation satellites, while the other eight are Full Operational Capability (FOC) satellites. Although the first pair of FOC satellites suffered from a launch anomaly resulting in an elliptical orbit, these satellites can be used for scientific applications without relevant limitations. The quality of broadcast orbits and clocks has significantly improved since the beginning of routine transmissions and has reached a signal-in-space range error of 30 cm. Precise orbit products generated by the scientific community achieve an accuracy of about 5 cm if appropriate models for the solar radiation pressure are applied. The latter is also important for an assessment of the clock stability as orbit errors are mapped to the apparent clock. Dual-frequency single point positioning with broadcast orbits and clocks of nine Galileo satellites that have so far been declared healthy already enables an accuracy at a few meters. Galileo-only precise point positioning approaches a precision of 2 cm in static mode using daily solutions.  相似文献   

Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results   总被引：59，自引：0，他引：59  

Oliver Heiri  André F. Lotter  Gerry Lemcke 《Journal of Paleolimnology》2001,25(1):101-110

Five test runs were performed to assess possible bias when performing the loss on ignition (LOI) method to estimate organic matter and carbonate content of lake sediments. An accurate and stable weight loss was achieved after 2 h of burning pure CaCO₃ at 950 °C, whereas LOI of pure graphite at 530 °C showed a direct relation to sample size and exposure time, with only 40-70% of the possible weight loss reached after 2 h of exposure and smaller samples losing weight faster than larger ones. Experiments with a standardised lake sediment revealed a strong initial weight loss at 550 °C, but samples continued to lose weight at a slow rate at exposure of up to 64 h, which was likely the effect of loss of volatile salts, structural water of clay minerals or metal oxides, or of inorganic carbon after the initial burning of organic matter. A further test-run revealed that at 550 °C samples in the centre of the furnace lost more weight than marginal samples. At 950 °C this pattern was still apparent but the differences became negligible. Again, LOI was dependent on sample size.An analytical LOI quality control experiment including ten different laboratories was carried out using each laboratory's own LOI procedure as well as a standardised LOI procedure to analyse three different sediments. The range of LOI values between laboratories measured at 550 °C was generally larger when each laboratory used its own method than when using the standard method. This was similar for 950 °C, although the range of values tended to be smaller. The within-laboratory range of LOI measurements for a given sediment was generally small. Comparisons of the results of the individual and the standardised method suggest that there is a laboratory-specific pattern in the results, probably due to differences in laboratory equipment and/or handling that could not be eliminated by standardising the LOI procedure.Factors such as sample size, exposure time, position of samples in the furnace and the laboratory measuring affected LOI results, with LOI at 550 °C being more susceptible to these factors than LOI at 950 °C. We, therefore, recommend analysts to be consistent in the LOI method used in relation to the ignition temperatures, exposure times, and the sample size and to include information on these three parameters when referring to the method.  相似文献   

Markov chain Monte Carlo methods for conditioning a permeability field to pressure data   总被引：3，自引：0，他引：3  

Dean S. Oliver  Luciane B. Cunha  Albert C. Reynolds 《Mathematical Geology》1997,29(1):61-91

Generating one realization of a random permeability field that is consistent with observed pressure data and a known variogram model is not a difficult problem. If, however, one wants to investigate the uncertainty of reservior behavior, one must generate a large number of realizations and ensure that the distribution of realizations properly reflects the uncertainty in reservoir properties. The most widely used method for conditioning permeability fields to production data has been the method of simulated annealing, in which practitioners attempt to minimize the difference between the ’ ’true and simulated production data, and “true” and simulated variograms. Unfortunately, the meaning of the resulting realization is not clear and the method can be extremely slow. In this paper, we present an alternative approach to generating realizations that are conditional to pressure data, focusing on the distribution of realizations and on the efficiency of the method. Under certain conditions that can be verified easily, the Markov chain Monte Carlo method is known to produce states whose frequencies of appearance correspond to a given probability distribution, so we use this method to generate the realizations. To make the method more efficient, we perturb the states in such a way that the variogram is satisfied automatically and the pressure data are approximately matched at every step. These perturbations make use of sensitivity coefficients calculated from the reservoir simulator.  相似文献   

Calculations of the seasonal loadings of North Sea sediments with persistent aromatic organochlorines     

Dipl. Ing. Dr. Rainer Knickmeyer  Staatl. gepr. Lebensmittelchem. Oliver Landgraff  Prof. Dr. Hans Steinhart 《Ocean Dynamics》1990,43(6):289-309

The content and distribution of ΣPCB (as the sum of 24 individual components), HCB and p,p′-DDE was determined in sediments taken from the North Sea during two seasons. The mass-balance of aromatic organochlorine compounds in the upper 2 cm of sediments is calculated and dicussed in relation to pollutant dispersal.  相似文献   

Nonlinear kinetic Alfvén wave with Poisson equation correction in the low aurora     

De Yu Wang  Guang Li Huang  C. -G. Fälthammar  P. A. Lindqvist  L. Blomberg  Li Ting Song 《Astrophysics and Space Science》1996,240(2):175-186

Nonlinear kinetic Alfvén waves where m _e /m _i , have been solved both with and without the Poisson equation correction. It is found that the ratio of the perpendicular electric field and magnetic field, and the ratio of parallel and perpendicular electric field increase with deepening of the depressive density soliton. The former ratio may be larger than the Alfvén velocity in the case of a large amplitude solitary kinetic Alfvén wave. The Poisson equation correction is important for the nonlinear kinetic Alfvén wave propagating along the magnetic field, which solves a puzzle of Sagdeev potential to approach infinity in the limit ofK _x 0. This correction causes the solitary KAW possessing an electrostatic character along the direction of wave moving frame. These results have been compared with the observations from the Freja satellite in the low aurora.  相似文献   

Analysis of the Behavior of Sedimentary Rocks Under Impact Loading     

Oliver Millon  Maria Luisa Ruiz-Ripoll  Tobias Hoerth 《Rock Mechanics and Rock Engineering》2016,49(11):4257-4272

  相似文献   

Promoting green industrial development through local content requirements: India's National Solar Mission     

Oliver Johnson 《Climate Policy》2016,16(2):178-195

In order to make renewable energy technology deployment strategies politically acceptable, many countries are linking them to other socio-economic goals. A controversial industrial policy tool that is increasingly popular is the use of local content requirements (LCRs). These regulate the extent to which certain projects must use local products and are often justified on the basis of supporting local employment and private sector development. The LCR debate has centred on the rights and wrongs of protecting infant industry, with little progress being made in finding common ground. This article aims to move beyond this stalemate to understand conditions under which LCRs might be an effective tool for promoting local manufacturing. To do so, an effectiveness framework is applied to LCRs for solar photovoltaics in India's National Solar Mission. The article finds that for LCRs to be effective, they must be (1) limited in duration and incorporate planned evaluation phases, (2) focused on technologies and components for which technical expertise is available and global market entry barriers are manageable, and (3) linked to training and promotion of business linkages and linked to support for other stages of the value chain and wider services integral to success of renewable energy industries.

Policy relevance

It is widely appreciated that governments need to support renewable energy technology deployment in order to mitigate climate change. However, policy makers face increasing pressure to link such support with other socio-economic goals, such as job creation, economic development, and poverty reduction. One such policy support mechanism is the use of local content requirements (LCRs) linked to feed-in tariffs. Policy makers are faced with a difficult choice as manufacturing interest groups lobby for the establishment of protection measures such as LCRs whilst the international trade community led by the World Trade Organization (WTO) seeks to limit their use. This difficulty is amplified by the limited information on the impact of LCRs on job creation and economic development. In this context, this article documents the use of LCRs in India's National Solar Mission and seeks to understand the conditions under which LCRs are an effective policy tool for building a competitive local manufacturing industry.  相似文献