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排序方式: 共有214条查询结果,搜索用时 15 毫秒
21.
Summary The impact of the Arctic Oscillation (AO) on the winter surface air temperature (SAT) over Iran is demonstrated. Winter SAT
data for 50 years (1951–2000) are analyzed for the negative and the positive AO phases. Using the Median Sequential Correlation
Analysis (MSCA) technique it is shown that the winter SAT is negatively correlated to the winter AO index for most parts of
Iran. The winter AO index accounts for about 14% to 46% of the winter SAT variance. The positive (negative) SAT anomaly is
found to be associated with the onset of the negative (positive) phase. The overall probability of below long-term mean temperature
during the positive and the negative phases are estimated to be around 70% and 25%, respectively. For the negative phase,
westerly winds that originate from the warm Atlantic regions increase over Iran and consequently positive temperature anomalies
are found across the country. The positive AO phase is accompanied by northerly winds that allow continental polar and arctic
air masses to move into Iran, producing below normal temperatures. The summer AO is found to explain about 25–32% of the winter
SAT variance in Iran. The reason for this is explained by the significant correlation (+0.38) between the summer and the following
winter AO indices. These results indicate that the summer climate is linked to changes in atmospheric circulation which persist
through to the following autumn and winter. 相似文献
22.
Scattering of SH waves in a half-space with simple overground structures is studied analytically. For two-dimensional structures, such as shells, shear walls and a slab-bridge over a river, the method of matched asymptotics is used for sinusoidal waves long compared to the thickness of the structures. Resonance features are deduced analytically and calculated numerically for various incidences and other parameters. 相似文献
23.
N. Wassif A. M. Kafafy E. M. Abdel Aal A. Abdeldayem H. Odah R. Mostafa 《Arabian Journal of Geosciences》2014,7(9):3455-3466
Ore microscopic study was carried out on a great number of samples collected from four well-dated alkaline rock masses (ring complexes), namely Gabal Mishbeh, Gabal Nigrub El Fogani, Gabal Nigrub El Tahtani, and Gabal El Gezira located in the Eastern Desert of Egypt. These rings consist mainly of wide variety of rock types ranging from basic to acidic and from under saturated to quartz bearing. The opaques of the basic rocks consist mainly of various ilmenite–magnetite intergrowths and differ essentially from those of the acidic rocks where minor amount of titanomagnetite is present. Numerous exsolution, replacement, and deformational textures were described. The distribution of opaque minerals and their intergrowths in the four well-defined ring complexes is described. Systematic rock magnetic measurements such as natural remanent magnetization intensity and initial susceptibility, Curie point, saturation magnetization, and coercive force were carried out, and their results were discussed in the light of opaque mineralogical studies. 相似文献
24.
Application of artificial intelligence techniques for predicting the flyrock distance caused by blasting operation 总被引:2,自引:0,他引:2
Ebrahim Ghasemi Hasel Amini Mohammad Ataei Reza Khalokakaei 《Arabian Journal of Geosciences》2014,7(1):193-202
Flyrock arising from blasting operations is one of the crucial and complex problems in mining industry and its prediction plays an important role in the minimization of related hazards. In past years, various empirical methods were developed for the prediction of flyrock distance using statistical analysis techniques, which have very low predictive capacity. Artificial intelligence (AI) techniques are now being used as alternate statistical techniques. In this paper, two predictive models were developed by using AI techniques to predict flyrock distance in Sungun copper mine of Iran. One of the models employed artificial neural network (ANN), and another, fuzzy logic. The results showed that both models were useful and efficient whereas the fuzzy model exhibited high performance than ANN model for predicting flyrock distance. The performance of the models showed that the AI is a good tool for minimizing the uncertainties in the blasting operations. 相似文献
25.
Mostafa Moradi Dashtpagerdi Seyed Javad Sadatinejad Rafat Zare Bidaki Ehsan Khorsandi 《Journal of the Indian Society of Remote Sensing》2014,42(1):179-186
In this paper, remote sensing and GIS have been used to assess the status of NO2 at the south west of Iran. 221 data about concentration of NO2 was extracted from Ozone Monitoring Instrument. Ordinary kriging and inverse distance weighting interpolation methods was used to interpolate data. Results showed that ordinary kriging method using cross-validation have had less error. North east of the study area has the highest concentration of NO2 (329 molecule/cm2) and the concentration of NO2 decreases from north east to South west of the study area. On the other hand, data trend results showed that the data seems to exhibit a fairly strong trend in the east west direction and a weaker one in the north–south direction. 相似文献
26.
Natural Hazards - Landslides can cause extensive damage, particularly those triggered by earthquakes. The current study used back propagation of an artificial neural network (ANN) to conduct risk... 相似文献
27.
Farhadian Ali Ghasemi Ebrahim Hoseinie Seyed Hadi Bagherpour Raheb 《Geotechnical and Geological Engineering》2022,40(6):3343-3356
Geotechnical and Geological Engineering - Rock abrasivity index (RAI) and uniaxial compressive strength (UCS) are two key parameters for assessing abrasivity and durability of building stones,... 相似文献
28.
This study integrates remote sensing data and geoelectrical dipole–dipole resistivity to delineate near-surface palaeochannels and shallow aquifer in the northern part of Abu Dhabi Emirate, United Arab Emirates. The shuttle imaging radar images and shuttle radar topographic mission DEM were used to delineate near-surface palaeochannels visually based on the contrast between bright and dark tone and automatically using the eight-direction flow model. The delineated palaeochannels were validated by comparing the textural features evident from advanced land observing satellite-phased array type L-band synthetic aperture radar images and determining whether these patterns were different. Field observation and geoelectrical dipole–dipole resistivity method was used to define the depth of palaeochannels and lithology of the shallow aquifer. The remote sensing and geophysical investigations in the UAE, including the study area, indicate the presence of buried palaeochannels with south-west and north-west flow directions from Oman Mountain. The study area can be of economic importance to the local population. 相似文献
29.
Summary This study attempts to find possible linkages between the NCP index and the winter temperature variability over Iran. The
investigation is based on statistical analysis of simple, partial and multiple correlations and also evaluation of composite
maps of the extreme NCP index and maps of correlation between atmospheric variables and the temperature time series.
Our results show that the NCP has a strong negative correlation with the winter temperature in Iran. Furthermore, combination
of both the NCP and the AO (Arctic Oscillation) indices improve the correlations in all stations, implying both NCP and AO
can be considered as major patterns for explaining the Iranian winter temperature variability. The results show that the positive
NCP is associated with enhanced precipitation and cloudy conditions, consequently causing below normal temperature over Iran.
The anomalies of OLR in this phase are also negative, implying a cloudy sky. For the negative NCP phase these results are
completely reversed. The correlation maps indicate that the NCP is negatively/positively correlated with winter Outgoing Long-wave
Radiation/precipitation over Iran. The results also show that the SLP and GPH patterns are quite different for the positive
and negative NCP phases over Iran. During the negative NCP a small cyclone is formed over the Arabian Sea causing a strong
easterly towards Iran. During the positive NCP this cyclone is removed. Our results show that for the positive NCP years an
upper-level trough is formed over northern Iran and the eastern Mediterranean. For the negative NCP years this trough becomes
weak and is located over central European regions. This trough is closely linked with the winter temperature over Iran. This
is expressed by a high correlation between 500-hPa geopotential height at this region and Iranian winter temperature.
Authors’ addresses: A. R. Ghasemi, Climate Research Center, Water Engineering Department, Agricultural Faculty, Shiraz University,
Shiraz, Iran; D. Khalili, Water Engineering Department, Agricultural Faculty, Shiraz University, Shiraz, Iran. 相似文献
30.
Mohamed Mostafa Mohamed 《国际地球制图》2017,32(10):1120-1138
This study has modified an approach based on fuzzy logic in a GIS and multi-criteria decision making (MCDM) for groundwater potentiality mapping in Al Fo’ah area, the United Arab Emirates. The proposed approach uses nine groundwater conditioning factors recognized by local hydrology experts. Each factor and class of each factor was given a weight and score based on its level of contributions to groundwater accumulation using analytical hierarchy process and MCDM. Our results revealed that the areas of very high harbouring groundwater are located at the foot of the Oman mountains and occupies an area of about 8.46 km2 (4%) of the study area. We validated our results using the Relative Operating Characteristics. The area under the curve showed a ratio of 0.8957 (of 89.57%). The modified approach is timely and economically effective and can be applied in semi-arid regions to help hydrologists. 相似文献