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241.
Masoud Monjezi Hasan Ali Mohamadi Bahare Barati Manoj Khandelwal 《Arabian Journal of Geosciences》2014,7(2):505-511
In the blasting operation, risk of facing with undesirable environmental phenomena such as ground vibration, air blast, and flyrock is very high. Blasting pattern should properly be designed to achieve better fragmentation to guarantee the successfulness of the process. A good fragmentation means that the explosive energy has been applied in a right direction. However, many studies indicate that only 20–30 % of the available energy is actually utilized for rock fragmentation. Involvement of various effective parameters has made the problem complicated, advocating application of new approaches such as artificial intelligence-based techniques. In this paper, artificial neural network (ANN) method is used to predict rock fragmentation in the blasting operation of the Sungun copper mine, Iran. The predictive model is developed using eight and three input and output parameters, respectively. Trying various types of the networks, it was found that a trained model with back-propagation algorithm having architecture 8-15-8-3 is the optimum network. Also, performance comparison of the ANN modeling with that of the statistical method was confirmed robustness of the neural networks to predict rock fragmentation in the blasting operation. Finally, sensitivity analysis showed that the most influential parameters on fragmentation are powder factor, burden, and bench height. 相似文献
242.
We performed high resolution spectroscopy of the solar corona during the total solar eclipse of 22 July 2009 in two emission
lines: the green line at 5303 ? due to Fe xiv and the red line at 6374 ? due to Fe x, simultaneously from Anji (latitude 30°28.1′ N; longitude 119°35.4′ E; elevation 890 m), China. A two-mirror coelostat with
100 cm focal length lens produced a 9.2 mm image of the Sun. The spectrograph using 140 cm focal length lens in Littrow mode
and a grating with 600 lines per millimeter blazed at 2 μm provided a dispersion of 30 m? and 43 m? per pixel in the fourth
order around the green line and third order around the red line, respectively. Two Peltier cooled 1k × 1k CCD cameras, with
a pixel size of 13 μm square and 14-bit readout at 10 MHz operated in frame transfer mode, were used to obtain the time sequence
spectra in two emission lines simultaneously. The duration of totality was 341 s, but we could get spectra for 270 s after
a trial exposure at an interval of 5 s. We report here on the detection of intensity, velocity, and line width oscillations
with periodicity in the range of 25 – 50 s. These oscillations can be interpreted in terms of the presence of fast magnetoacoustic
waves or torsional Alfvén waves. The intensity ratios of green to red emission lines indicate the temperature of the corona
to be 1.65 MK in the equatorial region and 1.40 MK in the polar region, relatively higher than the expected temperature during
the low activity period. The width variation of the emission lines in different coronal structures suggests different physical
conditions in different structures. 相似文献
243.
The study was carried out in order to investigate existing hydrogeochemical relationships between groundwater environment
and geological units in the Kazan trona deposit area, Ankara, Turkey. Evaluations indicate that concentrations of alkalinity,
boron, chloride and sodium in the upgradient groundwater of the Eocene sedimentary units gradually increase toward downgradient
by the interactions of saline minerals (searlesite, shortite, northupite and pyrite) present in the secondary structures (microfractures
and irregular voids) at various levels. Inverse modeling calculations suggest that the range of dissolved mass amounts in
millimoles per kilogram of water for searlesite, shortite and northupite minerals are 0.05–28.67, 2.62–24.39 and 0.01–24.19,
respectively, in the aquifer between the upgradient and downgradient locations. The ranges of accompanying calcite and dolomite
precipitations are 4.54–48.71 and 2.16–24.08 mmol per kg of water, respectively. Chemical composition of the groundwater in
the overlying Neogene sedimentary unit includes also higher concentrations of the major ions as measured in groundwater of
the underlying units. However the lack of saline mineral zones in the Neogene unit indicates that upward groundwater mixing
takes place from the underlying aquifer as also suggested by the measured upward gradient. The mixing percentage of the underlying
groundwater as determined from the nested wells ranges from 2.7 to 48.3%, from upgradient to downgradient, respectively. The
unconfined alluvium aquifer overlying the Neogene unit includes relatively dilute groundwater except in two locations, where
high-ion concentrations detected in groundwater of the underlying units are also high in these locations, suggesting upward
groundwater mixing from the underlying aquifer due to upward gradient. However, groundwater input investigations from the
alluvium aquifer to the nearby Ova stream indicate that the detected high concentrations in these locations are diluted or
sorbed by the aquifer material toward downgradient (Ova Stream). 相似文献
244.
Aerosol optical properties over Solar Village, Saudi Arabia have been studied using ground-based remote sensing observations through the Aerosol Robotic Network (AERONET). Our analysis covered 8 recorded years of aerosol measurements, starting from February 1999 through January 2007. The seasonal mean values of aerosol optical thickness (AOT), the Ångström wavelength exponent α and the surface wind speed (V), exhibit a one year cyclical pattern. Seasonal variations are clearly found in the shape and magnitude of the volume size distribution (VSD) of the coarse size mode due to dust emission. The Spring is characterized by dusty aerosols as the modal value of the exponent α was low ~ 0.25 while that of AOT was high ~ 0.3. The modal value of wind speed was the highest ~ 3.6 m/s in spring. The increase in wind speed is responsible for increasing the concentration of dust particles during Spring. Spring of 2003 has the highest mean values of AOT, V and VSD and the lowest mean value for the exponent α. The seasonal mean values of the exponent α are anticorrelated with those of the wind speed (r = − 0.63). The annual mean values of the exponent α are well correlated (r = 0.77) with those of the difference between the maximum and minimum values of temperature ΔT. They are anticorrelated (r = − 0.74) with the annual mean values of the relative humidity. Large aerosol particles and high relative humidity increase the radiative forcing. This results in reduction of the values of the temperature difference ΔT. 相似文献
245.
Thamer Khazal Al-Ameri Afrah Hasan Al-Ekabi Sameer Noori Al-Jawad 《Arabian Journal of Geosciences》2014,7(4):1433-1455
Seventy-two core and cutting samples of the Ratawi Formation from selected wells of central and southern Iraq in Mesopotamian Foredeep Basin are analysed for their sedimentary organic matters. Dinoflagellates, spores and pollen are extracted by palynological techniques from these rocks. Accordingly, Hauterivian and late Valanginian ages are suggested for their span of depositional time. These palynomorphs with other organic matter constituents, such as foraminifer’s linings, bacteria and fungi, are used to delineate three palynofacies types that explain organic matter accumulation sites and their ability to generate hydrocarbons. Palaeoenvironments of these sites were mainly suboxic to anoxic with deposition of inshore and neritic marine environments especially for palynofacies type 2. Total organic matters of up to 1.75 total organic carbon (TOC) wt.% and early mature stage of up to 3.7 TAI based on the brown colour of the spore species Cyathidites australis and Gleichenidites senonicus with mottled interconnected amorphous organic matter are used for hydrocarbon generation assessment from this formation. On the other hand, these rock samples are processed with Rock-Eval pyrolysis. Outcomes and data calculations of these analyses are plotted on diagrams of kerogen types and hydrocarbon potential. Theses organic matter have reached the mature stage of up to T max?=?438 °C, hydrogen index of up to 600 mg hydrocarbons for each gram of TOC wt.% and mainly low TOC (0.50–1.55). Accordingly, this formation could generate fair quantities of hydrocarbons in Baghdad oil field and Basrah oil fields. Organic matters of this formation in the fields of Euphrates subzone extends from Hilla to Nasiriyah cities have not reached mature stage and hence not generated hydrocarbons from the Ratawi Formation. Software 1D PetroMod basin modelling of the Ratawi Formation has confirmed this approach of hydrocarbon generation with 100 % transformations of the intended organic matters to generate hydrocarbons to oil are performed in especially oil fields of East Baghdad, West Qurna and Majnoon while oil fields Ratawi and Subba had performed 80–95 % transformation to oil and hence end oil generation had charged partly the Tertiary traps that formed during the Alpine Orogeny. Oil fields of Nasiriyah and Kifle had performed least transformation ratio of about 10–20 % transformation to oil, and hence, most of the present oil in this field is migrated from eastern side of the Mesopotamian Foredeep Basin that hold higher maturation level. 相似文献
246.
Three aquifer systems as deep, middle, and shallow were identified in the Kazan trona ore deposit area. The flow conditions
and the interaction between various layers were conceptualized into a site hydrogeological model. Each aquifer system was
hydraulically and chemically characterized and represented in a numerical groundwater model. The resulting model has been
calibrated under steady-state and transient conditions using available data. The flow model was used in conjunction with a
three-dimensional solute transport model to assess the impacts of the pilot well solution mining of the trona deposit on groundwater
resources during operation and post-operation periods. The results of operation period indicate that, even under the worse
conditions (50 times increase in vertical hydraulic conductivity due to subsidence), ion contribution from the mine area with
118,000 mg/l maximum concentration would be about 58 mg/l into the deep aquifer system. This contribution is about 1.45% of
the existing concentration (4,000 mg/l) in the deep aquifer. After 1,000 years of post-operation period, ion contribution
from the mine area with maximum 119,000 mg/l concentration would be about 205 mg/l into the deep aquifer under extremely worse
conditions. This contribution is about 5–20% of present concentrations in the deep aquifer. Retardation factors, which were
not considered during model simulations would decrease the predicted concentrations. It is concluded that pilot well solution
mining of the trona deposit would not have significant impact on the quality of groundwater resources in the overlying aquifers. 相似文献
247.
根据1961—2012年湖泊水位观测资料,采用时间序列线性趋势分析与小波分析法,对比研究了博斯腾湖与伊塞克湖近50多年来水位变化特征,并对湖泊未来水位变化趋势进行预测。结果显示:(1)1961—2012年,博斯腾湖和伊塞克湖年水位总体呈显著的下降趋势。20世纪80年代中期之前,两湖水位变化趋势基本一致,都平稳下降;90年代后,博斯腾湖水位变化波动比伊塞克湖更为频繁,经历了迅速上升和下降的阶段,而伊塞克湖年水位较为稳定。(2)水位小波分析结果表明,博斯腾湖和伊塞克湖年水位变化分别存在18a和22a的主周期,从水位未来变化趋势预测结果来看,博斯腾湖水位将来一段时间继续下降,伊塞克湖水位则继续上升。 相似文献
248.
Salam Roquia Islam Abu Reza Md. Towfiqul Shill Badhon Kumar Alam G. M. Monirul Hasanuzzaman Md. Hasan Md. Morshadul Ibrahim Sobhy M. Shouse Roger C. 《Natural Hazards》2021,106(1):529-529
Natural Hazards - The article was published with a spelling error in one of the co-author names. The correct spelling is reflected in this correction, and the original work has been updated to... 相似文献