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Self-burial processes of finite-length cylinders under oscillatory flows and waves plus currents were examined with the following two different experimental facilities: a large oscillating water-sediment tunnel (LOWST) and a large wave-current tank. More than 130 experiments, with different model cylinders, were conducted within both facilities. The burial mechanisms studied include burial due to local scour and bedform migration. Burial due to fluidization in the tunnel was also explored, but only in a qualitative way. In the case of experiments with LOWST, the equilibrium burial depth was found to be a power function of the shields parameter (thetas). In the wave-current tank, the equilibrium burial depth was also found to be a function of the Shields parameter, albeit with larger scatter. The experimental observations made in both facilities have similar trends but different magnitudes. For equivalent values of the Shields parameter, smaller equilibrium burial depths were observed in the wave flume when compared to the ones in LOWST. After burial induced by local scour takes place, bedform (ripples and sandwaves) formation and evolution play a strong and, in some cases, dominant role on the equilibrium burial depth of the cylinders. Depending on how the vertical dimensions of bedforms compare to the specimen's diameter, cyclical covering and uncovering of the object may take place due to the passage of the migrating sandwaves. In such case, burial depth Bd no longer coincides with the vertical displacement (Vd) of the object as in the case when the burial process is dominated by local scour. 相似文献
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Ibrahim Sönmez Ahmet Emre Tekeli Erdem Erdi Fatih Demir Murat Arslan 《Arabian Journal of Geosciences》2014,7(8):3389-3398
Validation of the active fire monitoring (FIR) product from Spinning Enhanced Visible and Infrared Imager sensor of Meteosat Second Generation satellite is performed over Turkey. Ground truth data from the Ministry of Environment and Forestry for the years 2007, 2008, and 2009 is used by taking the active fire months of April–September into consideration. The contingency tables are obtained on a monthly basis and categorical statistics of probability of detection (POD) and false alarm rate (FAR) are derived. The results are introduced for each subclass, namely probable, possible, and combined cases. The highest POD amounts of 8.5, 1.93, and 9.4 % are obtained for the possible, probable, and combined cases, respectively, with the lowest FAR amounts of 70.9, 4.5, and 86.1 % for the same categories. FIR product validation with respect to predefined burnt area thresholds is introduced in the second part of the study in order to investigate burnt area effect in active fire detection. Increasing POD values with respect to burnt area amount is obtained with relatively higher values in probable than possible type. On the other hand, FAR variation is observed to be not correlated with the burnt area amount. 相似文献
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Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of hydraulic data. This study presents Linear Genetic Programming (LGP), which is an extension to GP, as an alternative tool in the prediction of scour depth below a pipeline. The data sets of laboratory measurements were collected from published literature and were used to develop LGP models. The proposed LGP models were compared with adaptive neuro-fuzzy inference system (ANFIS) model results. The predictions of LGP were observed to be in good agreement with measured data, and quite better than ANFIS and regression-based equation of scour depth at submerged pipeline. 相似文献
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In this study, a modification to the chemical mass balance (CMB) receptor model presented in an earlier work was expanded to account for the changes in volatile organic compound (VOC) source fingerprints due to atmospheric reactions of VOCs that take place after being emitted to the atmosphere. The photochemical reactions consume VOCs that participate in, causing changes in the source fingerprints. These changes are of considerable magnitude when the travel durations from the source to the receptor (measurement point) are considered. The current study focuses on expansion of the integrated reaction rates of VOCs with ambient reactive species such as OH ? , O3, NO3, and O ? in order to estimate the source emission profiles simultaneously at the receptor site. Two test cases with different travel times and with different ambient OH ? , O3, and NO3 concentrations were also provided to compare the standard model, the modified model suggested in the previous work, and the current modification. F‐tests were also performed to determine whether the changes in source compositions are significant or not. The results from both the standard model and the modified model were evaluated in terms of χ2, R2, percent mass apportioned (MA), and a best fit (BF) measure. Maximum values of BF for the test cases from the three models were 0.70 ± 0.03, 0.74 ± 0.05, and 1.000 ± 0.00, respectively, indicating that the current modification increases the performance of two previous models and was better in explaining the effects of chemical reactions of VOCs. 相似文献
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ABSTRACTThe growing availability of smart devices with advanced sensors has increased the opportunities for citizen science applications for environmental monitoring. Accurate and widespread monitoring of river stage is vital for modeling water resources. Reliable data points are required for model calibration and validation in forecast studies. While current embedded monitoring systems provide accurate measurements, the cost to replicate these systems on a large domain is prohibitively expensive, limiting the quantity of data available. This project describes a new method to accurately measure river levels using smartphone sensors. Pictures of the same point on the river’s surface are taken to perform calculations based on the GPS location and spatial orientation of the smartphone. The proposed implementation is significantly more accessible than existing water measuring systems while offering similar accuracy. A case study is performed to evaluate the accuracy and sensitivity of the measurements to changes in distance. 相似文献
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About 400 km of new seismic reflection data has been acquired in the study region offshore of Alaçatı, Doğanbey, and Kuşadası, which enables investigation of the active crustal deformation in this region. The deformation onshore in western Turkey is dominated by crustal extension, and clear evidence of this process is also now available from this offshore area. However, in the onshore area adjacent to this study region evidence of active right-lateral strike-slip faulting has also previously been observed. This strike-slip faulting has previously been thought only to accommodate variations in extension between adjacent normal faults. However, in the offshore area there is considerable evidence of zones of deformation, some of which may link to the strike-slip faulting onshore, suggesting that strike-slip faulting may be of greater importance in this region than previously thought. 相似文献
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C. Karaguzel I. Gulgonul C. Demir M. Cinar M.S. Celik 《International Journal of Mineral Processing》2006
Abundant reserves of Na-feldspar (albite) and K-feldspar (orthoclase or microcline) are found in granites, syenite, tracite and pegmatites. As both feldspar minerals have similar chemical structure and physicochemical properties, their separation is challenging. Flotation is known to be the only technique to enable their separation. The fundamentals on the separation of these minerals were well documented in our earlier studies. In this study, a pegmatite ore with a K2O/Na2O (3.78:3.37) ratio of 1.12 was studied in a Denver flotation cell both at natural and acidic pH using HF and H2SO4. Because of the perthitic structure of the ore no significant separation is observed at natural pH. Interestingly, a selective separation was achieved at low pH using HF and H2SO4 (pH 2.5–2.8). The selectivity is induced by the addition of Na+ ions through depression of albite. Selective separation has been carried out by stagewise flotation using the tree technique. Accordingly, a pegmatite ore composed of 3.37% Na2O and 3.78% K2O is upgraded to 10.51% K2O and 3.02% Na2O with a K2O/Na2O = 3.48 in HF medium and to 2.55 in H2SO4 medium. It is shown that products recovered in other stages are also considered as commercially significant. Especially, quartz, which is recovered in the tailings in HF medium, is suitable for glass industry. The overall results show that commercial utilization of these results is possible. 相似文献
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Bulent Bayram Dursun Zafer Seker Akhtar Jamil Hatice Catal Reis Nusret Demir Salih Bozkurt Abdulkadir Ince Turgay Kucuk 《Arabian Journal of Geosciences》2018,11(12):319
Obtaining information about tree species distribution in agricultural lands is a topic of interest for various applications, such as tree inventory, forest management, agricultural land management, crop estimation, etc. This information can be derived from images obtained from modern remote sensing technology, which is the most economical way as compare to field surveys covering large geographic areas. Therefore, in this study, a new method is proposed for extraction and counting of sparse and regular distributed individual pistachio trees from agricultural areas on large scale from high-resolution digital ortho-photo maps, which were obtained using an airborne sensor (Ultracam-X). The input images were first smoothed by applying Gaussian filter to reduce the impact of noise. Normalized difference vegetation indices (NDVI) were then derived to obtain vegetation areas followed by Otsu’s global thresholding algorithm to obtain candidate tree areas. Further, connected component (CC) analysis was applied to segregate each object. Morphological processing was performed to fill holes within tree objects and get smooth contours, which were obtained by using the Moore-neighbor tracing method (MNTM) for each CC, while geometrical constraints were applied to undermine possible non-tree elements from output image. To further improve the segmentation results for sparse trees, a new method was applied, called quadratic local analysis (QLA). QLA helped to segment the trees, which were missed by the Otsu method due to low contrast and resulted in improved accuracy (3–6%). The obtained results were compared with well-known support vector machine (SVM) classifier. Proposed method produced slightly better results (1–5%) than SVM for extraction of pistachio trees and obtained accuracy for QLA and SVM were 96 and 91% for region 1, while 91 and 90% for region 2 respectively. 相似文献
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Natural Hazards - Landslides occur when masses of rock, earth, and other debris move down a slope. The slope of an area is directly responsible for the magnitude of the landslide. Being... 相似文献