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1.
Abstract

The scour phenomena around vertical piles in oceans and under waves may influence the structure stability. Therefore, accurately predicting the scour depth is an important task in the design of piles. Empirical approaches often do not provide the required accuracy compared with data mining methods for modeling such complex processes. The main objective of this study is to develop three data-driven methods, locally weighted linear regression (LWLR), support vector machine (SVR), and multivariate linear regression (MLR) to predict the scour depth around vertical piles due to waves in a sand bed. It is the first effort to develop the LWLR to predict scour depth around vertical piles. The models simulate the scour depth mainly based on Shields parameter, pile Reynolds number, grain Reynolds number, Keulegan–Carpenter number, and sediment number. 111 laboratory datasets, derived from several experimental studies, were used for the modeling. The results indicated that the LWLR provided highly accurate predictions of the scour depths around piles (R?=?0.939 and RMSE = 0.075). Overall, this study demonstrated that the LWLR can be used as a valuable tool to predict the wave-induced scour around piles.  相似文献   
2.
Mangroves are coastal ecosystems, found in tropical and subtropical regions around the world. They are found in the transitional zones between land, sea, and rivers. Petroleum hydrocarbons are the most common environmental pollutants, and oil spills pose a great hazard to mangroves forests. This research was focused on the isolation and characterization of crude oil‐degrading bacteria from mangrove ecosystems at the Persian Gulf. Sixty‐one crude oil‐degrading bacteria were isolated from mangrove samples (plant, sediment, and seawater) that enriched in ONR7a medium with crude oil as only carbon source. Some screening tests such as growth at high concentration of crude oil, bioemulsifier production, and surface hydrophobicity were done to select the most efficient strains for crude oil degradation. Molecular identification of strains was carried out by amplification of the 16S rRNA gene by PCR. The results of this study were indicated that the quantity of crude oil‐degrading bacteria was higher in the root of mangrove plants compare to other mangrove samples (sediment and seawater). Also, identification results confirmed that these isolated strains belong to Vibrio sp. strain NW4, Idiomarina sp. strain BW32, Kangiella sp. strain DP40, Marinobacter sp. strain DW44, Halomonas sp. strain BS53, and Vibrio sp. strain DS35. The application of bioremediation strategies with these bacteria can reduce crude oil pollution in this important marine environment.  相似文献   
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Geotechnical and Geological Engineering - The effects of diameter and location of drain pipes on the uplift force and exit hydraulic gradient for a gravity dam are investigated. A numerical model...  相似文献   
6.
Natural Resources Research - Blasting is the predominant rock fragmentation technique in civil constructions, underground and surface mines. Flyrock is the unwanted throw of rock fragments during...  相似文献   
7.
Theoretical and Applied Climatology - Gridded daily precipitation observations over the contiguous USA are used to investigate the past observed changes in the frequency and magnitude of heavy...  相似文献   
8.
Banerjee  Iman  Saha  Apala 《GeoJournal》2022,87(4):567-581

Urban regeneration involves the notion of reconstruction of places, where regeneration initiatives are undertaken to ameliorate the quality of physical and social spaces, accrue economic profitability of space, and finally encourage environmental sustainability. Railway stations all around the world have a very important role to play in contemporary urban regeneration strategies as places of both social and material interest. With the progress of the twentieth century several issues like rapidly growing population, seemingly relentless urbanisation, an alarming rate of vehicle emission, and consequent pollution emphasised railway stations as critical places with great potentials of infrastructure development for the optimised functioning of urban centres. Thus the huge value of railway stations and their adjacent land has been acknowledged since the last quarter of the previous century. This paper aims to analyse the place value of railway stations and their immediate neighbourhoods within the urban fabric of a city using a relevant theoretical concept i.e. the ‘Node-Place Model’. Simultaneously it also draws attention to the notion of (re)development of functional spaces in and around the railway stations as a dimension of contemporary urban regeneration strategies, with the help of some global examples. This paper thereby reveals that in the urban centres throughout the entire world the railway stations are progressively attaining the focal position within integrated transport and land use planning strategies, either under the larger concept of 'Transit-Oriented Development' (TOD) or more simply, with the label of (re)development programme. This paper will significantly contribute to the ability of spatial policymakers to direct the future of urban growth towards public transit stations so as to achieve sustainable urban development.

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9.
Effects of rainfall patterns on runoff and rainfall-induced erosion   总被引:3,自引:0,他引:3  
Rainfall-induced erosion involves the detachment of soil particles by raindrop impact and their transport by the combined action of the shallow surface runoff and raindrop impact.Although temporal variation in rainfall intensity(pattern)during natural rainstorms is a common phenomenon,the available information is inadequate to understand its effects on runoff and rainfall-induced erosion processes.To address this issue,four simulated rainfall patterns(constant,increasing,decreasing,and increasing-decreasing)with the same total kinetic energy were designed.Two soil types(sandy and sandy loam)were subjected to simulated rainfall using 15 cm×30 cm long detachment trays under infiltration conditions.For each simulation,runoff and sediment concentration were sampled at regular intervals.No obvious difference was observed in runoff across the two soil types,but there were significant differences in soil losses among the different rainfall patterns and stages.For varying-intensity rainfall patterns,the dominant sediment transport mechanism was not only influenced by raindrop detachment but also was affected by raindrop-induced shallow flow transport.Moreover,the efficiency of equations that predict the interrill erosion rate increased when the integrated raindrop impact and surface runoff rate were applied.Although the processes of interrill erosion are complex,the findings in this study may provide useful insight for developing models that predict the effects of rainfall pattern on runoff and erosion.  相似文献   
10.
Water Resources - Groundwater performs an important role in the territory of the plains Garmsar. In this study, on the basis of water samples, which were obtained from the wells of the region,...  相似文献   
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