排序方式： 共有25条查询结果，搜索用时 31 毫秒
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Dagasan Yasin Renard Philippe Straubhaar Julien Erten Oktay Topal Erkan 《Natural Resources Research》2019,28(1):153-171
Natural Resources Research - Geological contacts in lateritic metal deposits (footwall topographies) often delineate the orebody boundaries. Spatial variations seen in such contacts are frequently... 相似文献
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Detection of nitric acid (HNO<Subscript>3</Subscript>) in the atmosphere using the LOPAP technique 总被引：1，自引：0，他引：1
Jörg Kleffmann Traian Gavriloaiei Yasin Elshorbany Milagros Ródenas Peter Wiesen 《Journal of Atmospheric Chemistry》2007,58(2):131-149
A new instrument (LOPAP: LOng Path liquid Absorption Photometer) for the sensitive detection of nitric acid (HNO3) in the atmosphere is described. HNO3 is sampled in a temperature controlled stripping coil mounted in an external sampling module to minimize sampling artefacts in sampling lines. After conversion into a strongly absorbing dye, HNO3 is detected in long path absorption in special Teflon® AF 2400 tubes used as liquid core wave guides. For the correction of some interferences, due to for example HONO and particle nitrate, two channels are used in series. The interferences from several potential interfering compounds including particle nitrate were quantified in the laboratory and in a large outdoor simulation chamber. With the exception of the interference caused by N2O5, which is quantitatively measured by the instrument, all tested interferences can be corrected under atmospheric conditions. Thus, in the instrument only the sum of N(V) from HNO3 and N2O5 is determined, which is expected to be a common problem of wet chemical HNO3 instruments. The instrument has a detection limit of 5–30 pptv for a time response of 6–2 min, respectively and was validated against the FTIR technique in a large outdoor simulation chamber. In addition, the applicability of the instrument was demonstrated in a field campaign. 相似文献
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Yasin Makhloufi Elme Rusillon Maud Brentini Andrea Moscariello Michel Meyer Elias Samankassou 《Swiss Journal of Geoscience》2018,111(3):475-500
The Upper Jurassic carbonates represent important potential targeted reservoirs for geothermal energy in the Geneva Basin (Switzerland and France). Horizons affected by dolomitization, the focus of the present study, are of particular interest because they proved to be productive in time-equivalent deposits currently exploited in Southern Germany. The study is based on sub-surface samples and outcrops in the Geneva Basin. Petrographic analyses allowed to constrain the paragenesis of the Upper Jurassic units prior to discussing the cause(s) and effect(s) of dolomitization. Data reveal that the facies are affected by early and late diagenesis. All samples show at least two stages of burial blocky calcite cementation with the exception of those from the sub-surface, which display an incomplete burial blocky cementation preserving primary intercrystalline porosity. Dolomitization affected all units. The results point to an early dolomitization event, under the form of replacement dolomite. Dedolomitization, through calcitization and/or dissolution, is an important process, creating secondary pore space. Results of the present study favor a reflux model for dolomitization rather than the mixing-zone model suggested in earlier work. However, considering the geodynamic context, other dolomitization models cannot be excluded for the subsurface. The presence of secondary pore space might contribute to the connectivity of the porous network providing enhanced reservoir properties. These results are a first step towards a better understanding of the diagenetic history of the Upper Jurassic in the Geneva Basin. Moreover, it provides a reasonable framework for further geochemical analyses to constrain the nature and timing of fluid migration. The paragenesis and the dolomitization model hold the potential to help in ongoing exploration for geothermal energy beyond the Geneva Basin. 相似文献
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Yasin Dursun Sari 《Marine Georesources & Geotechnology》2013,31(6):567-571
The biologically induced cementation (BioGrout) method has been used in this study to improve engineering properties of soil. Laboratory tests have been carried out to quantify the effect of BioGrout treatment on the strength of two types of sand by using Sporosarcina pasteurii bacteria. Bearing strength and other parameters, such as colony forming units (number of bacteria), pH level, temperature, and amount of CaCO3, have also been studied. Calcification (cementation) through precipitation of CaCO3 on the mineral surfaces has been clearly observed from the images of a scanning electron microscope (SEM). Finally, the effect of sand material on the effectiveness of biocementation was investigated via employement of different sand types. 相似文献
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Two Cardium horizons from the topmost Azraq Formation in the eastern desert of Jordan were investigated and dated by U/Th at 330 ka; MIS 9. Fossil diversity and abundance, especially for Charophytes and gastropods with the absence of palygorskite, dolomite and evaporites, suggest the presence of a fresh water lake changing to a brackish environment at certain time intervals. A lake or possibly several smaller and shallower lakes occupied an area of about 50 km wide within the Azraq Basin. The present-day arid climate cannot support the presence of lakes in the eastern desert of Jordan, and thus MIS 9 in Jordan must have been much wetter. The source of humidity was most probably more intense Mediterranean cyclones associated with warmer than present MIS 9. However, the possibility of summer monsoon rain from the south cannot be fully excluded. 相似文献
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An early warning system forewarns an urban area of the forthcoming strong shaking, normally with a few seconds to a few tens
of seconds of early warning time before the arrival of the destructive S-wave part of the strong ground motion. For urban
and industrial areas susceptible to earthquake damage, where the fault rupture system is complex and the fault-site distances
are short, there is usually insufficient time to compute the hypocenter, focal parameters and the magnitude of an earthquake.
Therefore, simpler and robust early warning algorithm is needed. The direct (engineering) early warning systems are based
on algorithms of the exceedance of specified threshold time domain amplitude levels. The continuous stations’ data are processed
to compute specific engineering parameters robustly and compared with specified threshold levels. The parameters can be chosen
as band-pass filtered peak ground accelerations and/or the bracketed cumulative absolute velocity (BCAV). In this paper, an
enhancement to bracket cumulative absolute velocity for the application of online urban early warning systems results in a
new parameter called window based bracketed cumulative absolute velocity (BCAV-W). The BCAV-W allows computation of cumulative
absolute velocity in a specified window size and to include the vertical component of the motion. The importance of choosing
optimum window size for the cumulative absolute velocity BCAV-W is discussed and the correlations between BCAV-W and the macro-seismic
intensity are studied for three combinations of horizontal and vertical components of the motion. Empirical relationship is
developed to estimate BCAV-W as a function of magnitude, distance, fault mechanism, and site category based on 1,208 recorded
ground motion data from 75 earthquakes in active plate-margins. 相似文献
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