نتایج جستجو برای: artificial sediment

تعداد نتایج: 323933  

Journal: :civil engineering infrastructures journal 0
fatemeh barzegari instructor of agricultural department, payam noor university, iran. mohsen yousefi m.sc., faculty of natural resources, yazd university, iran ali talebi associate professor, faculty of natural resources, yazd university, iran.

the aim of this study was to estimate suspended sediment by the ann model, dt with cart algorithm and different types of src, in ten stations from the lorestan province of iran. the results showed that the accuracy of ann with levenberg-marquardt back propagation algorithm is more than the two other models, especially in high discharges. comparison of different intervals in models showed that r...

Journal: :Environmental science and pollution research international 2015
R Redelstein H Zielke D Spira U Feiler L Erdinger H Zimmer S Wiseman M Hecker J P Giesy T-B Seiler H Hollert

Predicting the bioavailability and effects of metals in sediments is of major concern in context with sediment risk assessment. This study aimed to investigate the bioavailability and molecular effects of metals spiked into riverine sediments to zebrafish (Danio rerio) embryos. Embryos were exposed to a natural and an artificial sediment spiked with cadmium (Cd), copper (Cu), nickel (Ni) and zi...

2012
Philip Greenwood

The environmental characteristics of many artificial gamma-emitting radionuclides provide a number of distinct advantages over other forms of fine-sediment tracer that are readily exploitable when undertaking erosion investigations. This makes them particularly effective for accurately measuring the movement of small quantities of fine-sediment, especially in low-energy environments where soil ...

2002
GOKMEN TAYFUR

Sheet sediment transport was modelled by artificial neural networks (ANNs). A three-layer feed-forward artificial neural network structure was constructed and a back-propagation algorithm was used for the training of ANNs. Event-based, runoffdriven experimental sediment data were used for the training and testing of the ANNs. In training, data on slope and rainfall intensity were fed into the n...

, , hezarkhani, najmeye, sepahvand, alireza,

Being available the accurate data on carried sediment has accounted as an important factor for making decision about constructing of river structures and determining of dam life. To accomplish this object, a number methods have been proposed so that sediment rate curving as a hydrological method has been developed for doing it. Ignoring differences between season's values causes to lower the pr...

2015

Prediction of highly non-linear behaviour of suspended sediment flow in rivers is of prime importance in environmental studies and watershed management. In this study, the predictive performance of artificial neural network (ANN) integrated with genetic algorithm (GA) was assessed. GA was used to optimize the parameters and architecture of the ANN. Five simulation scenarios (S1–S5) were develop...

2002
T. Yildirim H. K. Cigizoglu

The estimation and forecasting of the hydrologic data carry significance for many water resources engineering problems. Establishing sediment monitoring instruments on rivers is a costly operation. The methods available in literature for sediment concentration estimation are complicated, time consuming and necessitate cumbersome parameter estimation procedures. Artificial neural networks have b...

عمادی, علیرضا, فضل اولی, رامین, کیا, عیسی,

Sediment load estimation is one of the most important issues in rivers & dam reservoirs management and generally in water projects. Various empirical equations show that proper analytical or empirical method is not suggested for correct estimation of suspended sediment, yet. In the present study, to assessment of closer estimation to actual data of transported sediment in Ghoran Talar station l...

Journal: :مرتع و آبخیزداری 0
بهارک معتمدوزیری حسن احمدی محمد مهدوی فرود شریفی نصرا... جواهری

estimation of river sediment load is one of the most important issues in design of hydraulic structures, investigating water quality, conserving fish habitat, estimating erosion and determining watershed management effects. there are two methods for estimating sediment load: empirical and hydrological methods. existence of numerous empirical methods for estimation of river sediment load and a w...

Journal: :Environmental toxicology and chemistry 2001
L Samsøe-Petersen K Gustavson T Madsen B B Mogensen P Lassen K Skjernov K Christoffersen E Jørgensen

The fate of esfenvalerate was investigated by sampling and chemical analysis after spraying of an artificial pond (25 g a.i./ha) and in the laboratory with [14C]esfenvalerate by trapping of 14CO2 and fractionation of the sediment. The effects were investigated on pelagic communities in enclosures in a natural lake and in the laboratory on surface (Cymatia coleoptrata) and sediment (Chironomus r...

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