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461.

Blast-induced flyrock is a hazardous and undesirable phenomenon that may occur in surface mines, especially when blasting takes place near residential areas. Therefore, accurate prediction of flyrock distance is of high significance in the determination of the statutory danger area. To this end, there is a practical need to propose an accurate model to predict flyrock. Aiming at this topic, this study presents two machine learning models, including extreme learning machine (ELM) and outlier robust ELM (ORELM), for predicting flyrock. To the best of our knowledge, this is the first work that investigates the use of ORELM model in the field of flyrock prediction. To construct and verify the proposed ELM and ORELM models, a database including 82 datasets has been collected from the three granite quarry sites in Malaysia. Additionally, artificial neural network (ANN) and multiple regression models were used for comparison. According to the results, both ELM and ORELM models performed satisfactorily, and their performances were far better compared to the performances of ANN and multiple regression models.

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462.
The Iberian Massif poses a problem of relationships between its northwestern and southern parts. Suture terranes (ophiolites and high-pressure rocks) crop out in NW Iberia but only as allochthonous units, unconnected from their root zone. Sutures cropping out in SW Iberia are discussed in order to relate them to the unknown root of the NW Iberia allochthons. On the other hand, the Moroccan Variscides are very briefly presented with a view to propose their correlation with the Iberian zones. Particularly important is the transition from the Variscides to the Paleoproterozoic basement in Morocco, which is a key argument for palaeogeographic reconstructions.  相似文献   
463.
464.
The Aghajari Formation, called also the Upper Fars, develops throughout the Folded Zagros Zone and its thickness in the type section in southwest of Iran is 2966 meters. To analyze the sedimentary basin of this Formation, lithofacies, architectural elements and petrofacies of the related deposits in a section in southeast of Sarvestan in Fars Province of Iran with a thickness of 2221.45 meters were examined. Microscopically studying thin sections, the petrography and the occurrence of the deposits were determined. In this section, 16 lithofacies, 10 architectural elements and 2 sandstone petrofacies were identified. The lithofacies were divided into two major and minor groups, in which the major lithofacies consist of coarse-grained (Gh, Gp, Gt and Gm), medium-grained (Sh, Sp, St, Sl, Sm, Sr and Ss and fine-grained ones (Fm, Fl and Fsm), and the minor lithofacies were evaporative and mixed silisiclastic-carbonate. The identified architectural elements are CH, SB, GB, LA, DA, CR, CS, LV, LS, CH (FF) and FF. By combining evidences from facies analysis and architectural elements together, the Aghajari Formation was divided into three parts in which the related sedimentation environments, from top to bottom, are gravel, gravel-sand and fine-grained meandering river respectively. There have also been playas and shoreface in the lower part. Based on petrography, the sandstones of this formation were classified into two groups: litharenite and sublitharenite. The origin of these deposits (sandstones) was appointed to the recycled orogeny and the source of quartz is low and medium to high metamorphic rank. Using the field evidences, the paleocurrent direction was achieved indicating the direction of the paleocurrent from northwest to southeast at the time of deposition. It is hoped that these data can be used in the interpretation of the basin and reconstruction of the paleogeography in the local and regional scales.  相似文献   
465.
We undertake a spectral study of a sample of bright X-ray sources taken from six XMM-Newton fields at high galactic latitudes, where AGN are the most populous class. These six fields were chosen such that the observation had an exposure time more than 60 ksec, had data from the EPIC-pn detector in the full-Frame mode and lying at high galactic latitude |b|>25. The analysis started by fitting the spectra of all sources with an absorbed power-law model, and then we fitted all the spectra with an absorbed power-law with a low energy black-body component model.The sources for which we added a black body gave an F-test probability of 0.01 or less (i.e. at 99% confidence level), were recognized as sources that display soft excess. We perform a comparative analysis of soft excess spectral parameters with respect to the underlying power-law one for sources that satisfy this criterion. Those sources, that do not show evidence for a soft excess, based on the F-test probability at a 99% confidence level, were also fitted with the absorbed power-law with a low energy black-body component model with the black-body temperature fixed at 0.1 and 0.2 keV. We establish upper limits on the soft excess flux for those sources at these two temperatures. Finally we have made use of Aladdin interactive sky atlas and matching with NASA/IPAC Extragalactic Database (NED) to identify the X-ray sources in our sample. For those sources which are identified in the NED catalogue, we make a comparative study of the soft excess phenomenon for different types of systems.  相似文献   
466.
Cryoturbated Upper Chalk is a dichotomous porous medium wherein the intra‐fragment porosity provides water storage and the inter‐fragment porosity provides potential pathways for relatively rapid flow near saturation. Chloride tracer movement through 43 cm long and 45 cm diameter undisturbed chalk columns was studied at water application rates of 0·3, 1·0, and 1·5 cm h?1. Microscale heterogeneity in effluent was recorded using a grid collection system consisting of 98 funnel‐shaped cells each 3·5 cm in diameter. The total porosity of the columns was 0·47 ± 0·02 m3 m?3, approximately 13% of pores were ≥ 15 µm diameter, and the saturated hydraulic conductivity was 12·66 ± 1·31 m day?1. Although the column remained unsaturated during the leaching even at all application rates, proportionate flow through macropores increased as the application rate decreased. The number of dry cells (with 0 ml of effluent) increased as application rate decreased. Half of the leachate was collected from 15, 19 and 22 cells at 0·3, 1·0, 1·5 cm h?1 application rates respectively. Similar breakthrough curves (BTCs) were obtained at all three application rates when plotted as a function of cumulative drainage, but they were distinctly different when plotted as a function of time. The BTCs indicate that the columns have similar drainage requirement irrespective of application rates, as the rise to the maxima (C/Co) is almost similar. However, the time required to achieve that leaching requirement varies with application rates, and residence time was less in the case of a higher application rate. A two‐region convection–dispersion model was used to describe the BTCs and fitted well (r2 = 0·97–0·99). There was a linear relationship between dispersion coefficient and pore water velocity (correlation coefficient r = 0·95). The results demonstrate the microscale heterogeneity of hydrodynamic properties in the Upper Chalk. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
467.
While finding the optimal route for users with physical disabilities and personalizing routes for each user, on the one hand, and collaborative wayfinding, on the other hand, have been addressed in the pedestrian navigation systems literature, there has not been much research on combining the two activities. The problem associated with wayfinding approaches solely based on information about network segments and personal preferences is that the information about segments in the database may not, correctly and/or adequately address user preferences. The problem associated with wayfinding approaches solely based on the ratings given to routes by wheelchair users is the lack of rates (or scores) for all possible routes between all possible origin‐destination pairs in the network. This article discusses an approach to combine these two approaches for wayfinding to augment each other's shortcomings. To evaluate the personalized wayfinding approach, we utilize a route index, called a comparison index. The results show that with a P‐value of 9%, the routes obtained from our approach are more accessible than the routes obtained from another approach developed in another study. To evaluate the collaborative wayfinding approach, a Monte Carlo simulation was conducted which reflects the updates in routes as users' feedbacks become available.  相似文献   
468.
Soil erosion is a major environmental problem in arid and semi-arid areas. Although bioengineering is important in preventing soil erosion, plant architecture and mechanical properties in these areas are rarely studied. In this study, in order to evaluate the potential of native plants to reduce soil erosion in semi-arid regions, their above-ground (e.g., stem density, radius of the stem, etc.) and below-ground (e.g., root area ratio, root tensile strength, etc.) characteristics were measured in the field and laboratory. Five indicators, namely, stem density (SD), sediment obstruction potential (SOP), plant stiffness (MEI), relative soil detachment (RSD), and root cohesion (Cr), were taken into account. Each indicator was scored according to a five-point scale (0?=?low, 4?=?high), and then, the score of each indicator was represented on an ameba diagram. Finally, for understanding traits of plants and evaluating their potential to control rill and gully erosion, the area occupied by the ameba diagram was studied. The results indicated that the shrub Ziziphus spina-christi (MEI?=?108.35 N, RSD?=?0.398, Cr?=?8.34 kPa, SOP?=?0.097, and SD?=?0.00270) is a very suitable native plant species for controlling both the gully and rill erosion. In addition, Scariola orientalis is effective for sediment obstruction, but its low scores on the MEI and RSD indicators imply that it is not able to control gully development. Furthermore, Noaea mucronata, Platychaete glaucescens, Astragalus gummifer, Alhagi persarum, Lycium shawii, and Prosopis farcta have a distinct potential to reduce the rate of gully erosion. These results have wide applicability for adopting soil conservation measures to other semi-arid environments.  相似文献   
469.
Flash floods are considered to be one of the worst weather-related natural disasters. They are dangerous because they are sudden and are highly unpredictable following brief spells of heavy rain. Several qualitative methods exist in the literature for the estimations of the risk level of flash flood hazard within a watershed. This paper presents the utilization of remote sensing data such as enhanced Thematic Mapper Plus (ETM+), Shuttle Radar Topography Mission (SRTM), coupled with geological, geomorphological, and field data in a GIS environment for the estimation of the flash flood risk along the Feiran–Katherine road, southern Sinai, Egypt. This road is a vital corridor for the tourists visiting here for religious purposes (St. Katherine monastery) and is subjected to frequent flash floods, causing heavy damage to man-made features. In this paper, morphometric analyses have been used to estimate the flash flood risk levels of sub-watersheds within the Wadi Feiran basin. First, drainage characteristics are captured by a set of parameters relevant to the flash flood risk. Further, comparison between the effectiveness of the sub-basins has been performed in order to understand the active ones. A detailed geomorphological map for the most hazardous sub-basins is presented. In addition, a map identifying sensitive sections is constructed for the Feiran–Katherine road. Finally, the most influenced factors for both flash flood hazard and critical sensitive zones have been discussed. The results of this study can initiate appropriate measures to mitigate the probable hazards in the area.  相似文献   
470.
Phytoplankton and bacteria diversity were studied before, during and after red tide phenomena during spring season 2015 in the Eastern Harbour (E.H.) of Alexandria, Egypt. Fifty five species of phytoplankton were identified and represented different distinct classes “Bacillariophyceae; Dinophyceae, Chlorophyceae, Cyanophyceae and Eugelenophyceae”. Also, Diatom formed the most dominant group. The average number of the phytoplankton density varied from 4.8 × 104 to 1.1 × 106 cell l-1 during the study period and Skeletonema costatum was the agent causing the red tide. The existence percentages of bacteria ranged from 2.6 to 17.9% on all media tested. The bacterial isolates on the nutrient agar medium represented the highest existence with a total percentage of 43.6%, followed by MSA medium (25.7%), while the lowest percentage was for the AA medium at 7.8%. However, twelve isolates were selected as representative for bacterial community during study interval. Based on the morphological, biochemical, physiological and enzymatic characteristics, the bacterial strains were described. Depending on the 16S rDNA gene sequence, three common antagonists were aligned as: Vibrio toranzoniae strain Vb 10.8, Ruegeria pelagia strain NBRC 102038 and Psychrobacter adeliensis strain DSM 15333. The interaction between these bacteria and S. costatum was studied. The growth of S. costatum was significantly lower whenever each bacterium was present as compared to axenic culture. More specifically, 30% (v/v) of the all tested bacteria showed the strongest algicidal activities, as all S. costatum cells were killed after two days. 10% of R. pelagia and P. adeliensis also showed significant algicidal activities within six days.  相似文献   
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