排序方式： 共有28条查询结果，搜索用时 15 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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The non‐linear analysis of single‐degree‐of‐freedom (SDOF) systems provides the essential background information for both strength‐based design and displacement‐based evaluation/design methodologies through the development of the inelastic response spectra. The recursive solution procedure called the piecewise exact method, which is efficiently used for the response analysis of linear SDOF systems, is re‐formulated in this paper in a unified format to analyse the non‐linear SDOF systems with multi‐linear hysteresis models. The unified formulation is also capable of handling the P‐delta effect, which generally involves the negative post‐yield stiffness of the hysteresis loops. The attractiveness of the method lies in the fact that it provides the exact solution when the loading time history is composed of piecewise linear segments, a condition that is perfectly satisfied for the earthquake excitation. Based on simple recursive relationships given for positive, negative and zero effective stiffnesses, the unified form of the piecewise exact method proves to be an extremely powerful and probably the best tool for the SDOF inelastic time‐history and response spectrum analysis including the P‐delta effect. A number of examples are presented to demonstrate the implementation of the method. Copyright © 2003 John Wiley & Sons, Ltd. 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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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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Istanbul Earthquake Rapid Response and the Early Warning System 总被引：13，自引：0，他引：13
M. Erdik Y. Fahjan O. Ozel H. Alcik A. Mert M. Gul 《Bulletin of Earthquake Engineering》2003,1(1):157-163
One hundred strong motion accelerometers have been placed in populated areas of Istanbul, within an area of approximately
50×30 km, to constitute a network that will enable rapid shake map and damage assessment after a damaging earthquake. After
triggered by an earthquake, each station will process the streaming strong motion to yield the spectral accelerations at specific
periods and will send these parameters in the form of SMS messages to the main data center through available GSM network services.
A shake map and damage distribution will be automatically generated. The shake and damage maps will be available on the Internet
and will also be pushed to several end users. For earthquake early warning information ten strong motion stations were located
as close as possible to the Marmara Fault. The continuous on-line data from these stations will be used to provide near-real
time warning for emerging potentially disastrous earthquakes.
This revised version was published online in July 2006 with corrections to the Cover Date. 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