نتایج جستجو برای: sediment concentration and distribution

تعداد نتایج: 16928187  

Journal: :PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS 1988

Journal: :Journal of environmental sciences 2010
Wei Zhang Zhihong Zou Jun Sui

Most research conducted on the concentration distribution of sediment in the sedimentation tank does not consider the role of the suction dredge. To analyze concentration distribution more accurately, a suspended sediment transportation model was constructed and the velocity field in the sedimentation tank was determined based on the influence of the suction dredge. An application model was the...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت معلم تهران - دانشکده علوم 1372

in this study reference as one of the five cohesive devices in the achievement of textuality in english and persian narrative/descripitive written texts is focused on and analysed . to do so , the theoretical framework elaborated by halliday and hasan (1976) and its version adapted by the writer to match the sub-types of reference in farsi are applied to the analysis of reference in english and...

2007
H. S. Woo P. Y. Julien E. V. Richardson

Existing methods based on the diffusion theory have been extended to determine the sediment concentration distribution for large concentrations of sand. The modifications for volumetric concentrations ranging from 4 to 20% include decreased fall velocity, and increased viscosity and specific weight of the suspension. The sediment concentration profiles are sensitive to the velocity profiles and...

خراسانی, نعمت‌اله , رضایی, کرامت‌اله , زمانی, مجتبی, ‌ریاحی‌بختیاری, علی‌رضا,

In the present study, 10 egg samples of two bird species and 16 surface sediment samples were collected in order to determine the concentrations and origins of 23 PAH compounds. Then, PAH compounds were extracted using the clean-up method, following which the compounds were analyzed with the GC-MS. The total concentrations of the 22 PAH compounds (except for perylene) were determined within the...

2008
S. A. Talke H. E. de Swart H. M. Schuttelaars

Motivated by field studies of the Ems estuary which show longitudinal gradients in bottom sediment concentration as high as O(0.01 kg/m), we develop an analytical model for estuarine residual circulation based on currents from salinity gradients, turbidity gradients, and freshwater discharge. Salinity is assumed to be vertically well mixed, while the vertical concentration profile is assumed to...

Journal: :Bulletin of environmental contamination and toxicology 2008
H B Yin C X Fan S M Ding L Zhang B Li

There were similar distribution characteristics for acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in surface sediments, and the concentrations of AVS and SEM decreased from the deposition area to the center of the bay (lake). The ratio of AVS to SEM was <1 in the surface sediments, indicating that heavy metals in surface sediments may be bioavailable. The concentration ...

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