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An exact analytical method is described to solve the diffraction problem of a group of truncated vertical cylinders. In order to account for the interaction between the cylinders, Kagemoto and Yue's exact algebraic method is utilised (Kagemoto, H., Yue, D.K.P., 1986. Interactions among multiple three-dimensional bodies in water waves: an exact algebraic method. J Fluid Mech, 46, 129–139). The isolated cylinder diffraction potential is obtained using Garret's solution and evanescent mode solutions are derived in a similar manner (Garret, C.J.R., 1971. Wave forces on a circular dock. J Fluid Mech, 46, 129–139).Free surface elevations are calculated for an array of four cylinders and compared with experiments. Comparisons show good agreement. 相似文献
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Agostino Merico Toby Tyrrell Evelyn J. Lessard Temel Oguz Phyllis J. Stabeno Stephan I. Zeeman Terry E. Whitledge 《Deep Sea Research Part I: Oceanographic Research Papers》2004,51(12):1929
Several years of continuous physical and biological anomalies have been affecting the Bering Sea shelf ecosystem starting from 1997. Such anomalies reached their peak in a striking visual phenomenon: the first appearance in the area of bright waters caused by massive blooms of the coccolithophore Emiliania huxleyi (E. huxleyi). This study is intended to provide an insight into the mechanisms of phytoplankton succession in the south-eastern part of the shelf during such years and addresses the causes of E. huxleyi success by means of a 2-layer ecosystem model, field data and satellite-derived information. A number of potential hypotheses are delineated based on observations conducted in the area and on previous knowledge of E. huxleyi general ecology. Some of these hypotheses are then considered as causative factors and explored with the model. The unusual climatic conditions of 1997 resulted most notably in a particularly shallow mixed layer depth and high sea surface temperature (about 4 °C above climatological mean). Despite the fact that the model could not reproduce for E. huxleyi a clear non-bloom to bloom transition (pre- vs. post-1997), several tests suggest that this species was favoured by the shallow mixed layer depth in conjunction with a lack of photoinhibition. A top-down control by microzooplankton selectively grazing phytoplankton other than E. huxleyi appears to be responsible for the long persistence of the blooms. Interestingly, observations reveal that the high N:P ratio hypothesis, regarded as crucial in the formation of blooms of this species in previous studies, does not hold on the Bering Sea shelf. 相似文献
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Volkan Yilmaz Oguz Gungor 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(2):69-81
Image fusion is the production of high-resolution images by combining the spatial details of a high-resolution image with the spectral features of a low-resolution one. Reports of various quality metrics to evaluate the spectral and spatial qualities of fused images have been published. However, metrics may lead to misinterpretation due to inherent limitations in their mathematical algorithms. Hence, the use of additional assessment techniques in quality evaluation is reasonable. The purpose of the study was to compare the performances of several advanced fusion algorithms in order to help users in their choice of an appropriate fusion algorithm. Four different datasets were fused using advanced fusion algorithms, namely UNB PanSharp, Hyperspherical Color Space, High-Pass Filtering, Ehlers, Subtractive, Wavelet Single Band, Gram-Schmidt, Flexible Pixel-Based, and Criteria-Based. The spectral and spatial qualities of the fused images were evaluated using various quantitative procedures to ensure comprehensive and reliable comparison. The results showed that the Flexible Pixel-Based and High-Pass Filtering algorithms were very successful with regard to spatial quality, whereas the Flexible Pixel-Based and Criteria-Based algorithms were very successful with regard to spectral quality. The authors conclude that the Flexible Pixel-Based algorithm can be used for applications that require high spectral and spatial quality. 相似文献
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An exact analytical method is described to solve the diffraction problem of a group of truncated vertical cylinders. In order to account for the interaction between the cylinders, Kagemoto and Yue's exact algebraic method is utilised. The isolated cylinder diffraction potential due to incident waves is obtained using Garret's solution and evanescent mode solutions are derived in a similar manner.Numerical results are presented for arrays of two and four cylinders. Comparisons between the results obtained from the method presented here and those obtained from numerical methods show excellent agreement. 相似文献
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Sergey Konovalov Anatoliy Samodurov Temel Oguz Leonid Ivanov 《Deep Sea Research Part I: Oceanographic Research Papers》2004,51(12):273
New and published data on the distribution and speciation of manganese and iron in seawater are analyzed to identify and parameterize major biogeochemical processes of their cycling within the suboxic (15.6σt16.2) and anoxic layers (σt16.2) of the Black Sea. A steady-state transport-reaction model is applied to reveal layering and parameterize kinetics of redox and dissolution/precipitation processes. Previously published data on speciation of these elements in seawater are used to specify the nature of the transformations. Two particulate species of iron (Fe(III) hydroxide and Fe(II) sulfide) are necessary to adequately parameterize the vertical profile of suspended iron, while three particulate species (hydrous Mn(IV) oxide, Mn(II) sulfide, and Mn(II) carbonate) are necessary to describe the profile of suspended manganese. In addition to such processes as mixing and advection, precipitation, sinking, and dissolution of manganese carbonate are found to be essential in maintaining the observed vertical distribution of dissolved Mn(II). These results are used to interpret the observed difference in the form of vertical distribution for dissolved Mn(II) and Fe(II). Redox transformations of iron and manganese are coupled via oxidation of dissolved iron by sinking suspended manganese at σt16.2±0.2 kg m−3. The particulate manganese, necessary for this reaction, is supplied through oxidation of dissolved Mn(II). The best agreement with observations is achieved when nitrate, rather than oxygen, is set to oxidize dissolved Mn(II) in the lower part of the suboxic layer (15.90σt16.2). The results support the idea that, after sulfides of these metals are formed, they sink with particulate organic matter. The sinking rates of the particles and specific rates of individual redox and dissolved-particulate transformations have been estimated by fitting the vertical profile of the net rate. 相似文献
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Uncertainties in parameters of landslide susceptibility models often hinder them from providing accurate spatial and temporal predictions of landslide occurrences. Substantial contribution to the uncertainties in landslide assessment originates from spatially variable geotechnical and hydrological parameters. These input parameters may often vary significantly through space, even within the same geological deposit, and there is a need to quantify the effects of the uncertainties in these parameters. This study addresses this issue with a new three-dimensional probabilistic landslide susceptibility model. The spatial variability of the model parameters is modeled with the random field approach and coupled with the Monte Carlo method to propagate uncertainties from the model parameters to landslide predictions (i.e., factor of safety). The resulting uncertainties in landslide predictions allow the effects of spatial variability in the input parameters to be quantified. The performance of the proposed model in capturing the effect of spatial variability and predicting landslide occurrence has been compared with a conventional physical-based landslide susceptibility model that does not account for three-dimensional effects on slope stability. The results indicate that the proposed model has better performance in landslide prediction with higher accuracy and precision than the conventional model. The novelty of this study is illustrating the effects of the soil heterogeneity on the susceptibility of shallow landslides, which was made possible by the development of a three-dimensional slope stability model that was coupled with random field model and the Monte Carlo method.
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R. E. Masto L. C. Ram P. R. Shandilya S. Sinha J. George V. A. Selvi 《Environmental Earth Sciences》2011,64(4):1107-1115
Coal handling, crushing, washing, and other processes of coal beneficiation liberate coal particulate matter, which would
ultimately contaminate the nearby soils. In this study, an attempt was made to determine the status of soil bio-indicators
in the surroundings of a coal beneficiation plant, (in relation to a control site). The coal beneficiation plant is located
at Sudamudih, and the control site is 5 km away from the contaminated site, which is located in the colony of Central Institute
of Mining and Fuel Research Institute, Digwadih, Dhanbad. In order to estimate the impact of coal deposition on soil biochemical
characteristics and to identify the most sensitive indicator, soil samples were taken from the contaminated and the control
sites, and analyzed for soil organic carbon (SOC), soil N, soil basal respiration (BSR), substrate-induced respiration (SIR),
and soil enzymes like dehydrogenase (DHA), catalase (CAT), phenol oxidase (PHE), and peroxidase (PER). Coal deposition on
soils improved the SOC from 10.65 to 50.17 g kg−1, CAT from 418.1 to 804.11 μg H2O2 g−1 h−1, BSR from 8.5 to 36.15 mg CO2–C kg−1 day−1, and SIR from 24.3 to 117.14 mg CO2–C kg−1 day−1. Soils receiving coal particles exhibited significant decrease in DHA (36.6 to 4.22 μg TPF g−1 h−1), PHE (0.031 to 0.017 μM g−1 h−1), PER (0.153 to 0.006 μM g−1 h−1), and soil N (55.82 to 26.18 kg ha−1). Coal depositions significantly (P < 0.01) decreased the DHA to 8.8 times, PHE to 1.8 times, and PER to 25.5 times, but increased the SOC to 4.71 times, CAT
to 1.9 times, SIR to 4.82 times, and BSR to 4.22 times. Based on principal component analysis and sensitivity test, soil peroxidase
(an enzyme that plays a vital role in the degradation of the aromatic organic compounds) is found to be the most important
indicator that could be considered as biomarkers for coal-contaminated soils. 相似文献