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41.
Polycyclic aromatic hydrocarbons (PAHs) are types of hazardous contaminants, which their ingestion could cause severe consequences on human health. Leakages from storage tanks, underground pipelines, and evaporation ponds are the main sources of soil and groundwater contaminations at the Tehran Oil Refinery area (TOR site), located in south of Tehran, Iran. In this study, soil samples were collected from different locations at and adjacent to a polluted stream in the south of the refinery. The samples were analyzed for two hazardous PAH compounds, namely benzo[a]anthracene and acenaphthene. The clean up levels due to the accidental ingestion of contaminated soils at the site were also investigated in accordance to the U.S.EPA guidelines. Comparing the soil analysis results indicated that the benzo[a]anthracene concentrations in the samples varied from 53 to 299 mg/kg, which were higher than the clean up level of 1.17 mg/kg. Thus, soil remediation is required for this contaminant. The acenaphthene analysis results denoted that the average concentration of this contaminant was below the clean up level of 116.67 mg/kg, indicating that no treatment for this contaminant is necessary at the TOR site. Also, because the slope of the ground extends to the south of the stream, which stimulates the migration of the contaminants in this direction due to advection and dispersion mechanisms, the average of benzo[a]anthracene concentrations in south samples was higher than north samples (i.e., Cavg(S) = 160 ppm, Cavg(N) = 113 ppm). Various treatment techniques such as thermal desorption, soil vapor extraction (SVE), and solidification/stabilization (S/S) were investigated for this site. Due to moderate to high plasticity and relatively low permeability of the soil and low volatility of benzo[a]anthracene, however S/S method is recommended as a practical approach for the remediation of the soil at the site. 相似文献
42.
Several experimental methods have been proposed for consolidation test such as: constant loading rate, constant gradient and
constant rate of strain (CRS). Unfortunately, there are no unique criteria for performing the CRS consolidation test. Also,
there are considerable differences among the standards proposed for the test. In the present paper, authors have tried to
find the reasons for differences among standards, by studying the basic assumptions made on the characteristics of the pore
water flow during consolidation process. In the course of study, CRS consolidation tests were carried out under different
strain rates on remolded samples. The results of the tests have indicated that the Darcy’s law is not valid throughout the
CRS test and therefore, any consolidation equation based on Darcy’s law would not provide accurate results. The results of
the current experiments also showed that with regard to the applied strain rates, there are three different flow regimes governing
the process named as: pre-linear (non-Darcy flow), linear (Darcy flow) and post-linear (non-Darcy flow). Experimental results
also showed that distinction between boundaries of linear and nonlinear flow is possible from the excess pore pressure developed
during the tests. 相似文献
43.
Mina Yutani Takehiko Yagi Hitoshi Yusa Tetsuo Irifune 《Physics and Chemistry of Minerals》1997,24(5):340-344
In situ X-ray diffraction experiments of calcium ferrite-type MgAl2O4 have been carried out using a diamond anvil cell combined with synchrotron radiation and an imaging plate X-ray detector
under hydrostatic pressures up to 9 GPa. The observed unit-cell volumes at various pressures were fitted to the Birch-Murnaghan
equation of state, yielding a bulk modulus of K
T
0= 241(3) GPa when K′
T
0=4 is assumed. This relatively large bulk modulus of calcium ferrite-type MgAl2O4 is consistent with that expected from the systematic relation between bulk modulus and molar volume for the most compounds
possessing fcc oxygen packing.
Received March 5, 1996/Revised, accepted October 15, 1996 相似文献
44.
The current study provides a potential method for measuring current velocities during storms.
Water hyacinth debris, carried from the Nile outlet area by the offshore current, are washed ashore along the Israeli coasts
after southwesterly winter storms. The impact of the offshore current and wind on the floating debris is such that storms
of five days duration are sufficient to transport plants from the Nile to the Carmel coast, a distance of about 400 km. The
available information indicates a high rate of transport in the southeastern Mediterranean. 相似文献
45.
46.
Mina Ashrafi 《Astronomy& Geophysics》2007,48(4):4.35-4.37
Mina Ashrafi, winner of the Rishbeth Prize at the 2007 NAM, describes the work in her group at Southampton on the questions that a new multi-spectral imager – ASK – can answer about auroral structure and processes. 相似文献
47.
Evaluating Boolean,AHP and WLC methods for the selection of waste landfill sites using GIS and satellite images 总被引：2，自引：2，他引：0
Himan Shahabi Soroush Keihanfard Baharin Bin Ahmad Mohammad Javad Taheri Amiri 《Environmental Earth Sciences》2014,71(9):4221-4233
The city of Saqqez has a population of 140,000 people, making it one of the largest cities in Iran. Population growth, consumerism, and change in eating habits, such as the increased use of packaged products, is causing the accumulation of waste in this city to increase. In this study, the selection of a waste landfill site for Saqqez focused on 13 layers of geography information that was used by the IDRISI and Arc GIS software. Different models of the analytic multi-criteria decision-making process, such as an analytical hierarchy process (AHP), weighted linear combination (WLC), and Boolean logic, were used to manage layers to establish specific databases for urban waste landfills. Satellite images (Landsat ETM+ and SPOT 5), proposed sites and a land use map of the study area were also used. The results of this study indicated that two methods (AHP and WLC) in the early stages had better decision-making powers for locating landfill sites when compared to Boolean logic. Overlapping and compounding the similarities between these models in Arc GIS software, a 74-ha site was found. This site will be able to accept 130 tons of waste per day for the next 20 years. 相似文献
48.
Mehdi?Ashkartizabi Mina?AminghafariEmail author 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(1):83-104
In this paper, an efficient pattern recognition method for functional data is introduced. The proposed method works based on reproducing kernel Hilbert space (RKHS), random projection and K-means algorithm. First, the infinite dimensional data are projected onto RKHS, then they are projected iteratively onto some spaces with increasing dimension via random projection. K-means algorithm is applied to the projected data, and its solution is used to start K-means on the projected data in the next spaces. We implement the proposed algorithm on some simulated and climatological datasets and compare the obtained results with those achieved by K-means clustering using a single random projection and classical K-means. The proposed algorithm presents better results based on mean square distance (MSD) and Rand index as we have expected. Furthermore, a new kernel based on a wavelet function is used that gives a suitable reconstruction of curves, and the results are satisfactory. 相似文献