نتایج جستجو برای: sediment particles

تعداد نتایج: 191589  

Journal: :تحقیقات آب و خاک ایران 0
سیدحمیدرضا صادقی استاد/ دانشگاه تربیت مدرّس محبوبه کیانی هرچگانی دانشگاه تربیت مدرس حسین اسدی دانشگاه گیلان

splash detachment and transport of soil particles by raindrops are the initiating mechanisms of soil erosion by water. the size distribution of splashed particles is very important and effective in the rate of other erosion processes. however, this important issue has been less considered. therefore, the present study investigated individual and interaction effects of slope, rainfall intensity ...

Journal: :تحقیقات آب و خاک ایران 0
فرزام حسن نژاد شریفی دانش آموخته کارشناسی ارشد امیر صمدی دانشگاه بین المللی امام خمینی-قزوین-دانشکده فنی و مهندسی- گروه مهندسی آب اصغر عزیزیان قطار عضو هیات علمی گروه مهندسی آب

considering the importance of adequate roughness coefficient estimation in river engineering studies, evaluation of image processing technique in estimating manning’s roughness coefficient in the surface layer of riverbeds carried out in this study. the mentioned approach evaluation conducted by implementing of sieving analysis and digital image processing methods simultaneously for a 7.5km rea...

Journal: :J. Parallel Distrib. Comput. 2008
W. M. Charles E. van den Berg Hai-Xiang Lin Arnold W. Heemink Martin Verlaan

This paper describes the parallel simulation of sediment dynamics in shallow water. By using a Lagrangian model, the problem is transformed to one in which a large number of independent particles must be tracked. This results in a technique that can be parallelised with high efficiency. We have developed a sediment transport model using three different sediment suspension methods. The first met...

1997
Sharpe G L Curry D W Demichele

Alternative method for the calculation of mean time for the assessment of secondary production by true cohort analysis. Abstract-Particle-scavenged 234Th and *'OPb can be used to trace the fate of particulate matter reaching the deep-sea floor. We used this technique to demonstrate rapid ingestion of particles arriving at the sea floor (at a depth of 4,100 m) by mobile epibenthic holothuroids (...

2014
Morgane Houssais Carlos P. Ortiz Doug J. Durian Doug J. Jerolmack

Rivers shape continental surfaces; they erode continental reliefs, transport erosion products and finally deposit them in plains. As a consequence, understanding physics of sediment transport is of fundamental importance in earth sciences. However, sediment transport occurs at the dynamical interface between fluid and granular mechanics, which makes its full understanding challenging. Over the ...

2003
Neil Rooney Jacob Kalff Catherine Habel

The relationships between long-term (;115-year) phosphorus and sediment accumulation and submerged macrophyte biomass were determined both within a submerged macrophyte bed and among beds in Lake Memphremagog, Quebec, Canada. Strong relationships between present submerged macrophyte biomass and littoral-zone sediment and phosphorus accumulation rates both within and among macrophyte beds yielde...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه پیام نور - دانشگاه پیام نور مرکز - دانشکده علوم 1391

سنتز پلیمرهای کوئوردیناسیونی جدید از لیگاندهای 2-آمینو نیکوتینیک اسید، 2-کینولین کربوکسیلیک اسید، 2-پیرازین کربوکسیلیک اسید در ابعاد توده، با روش گرایان دمایی و با استفاده از شاخه ی جانبی انجام شده است، این پلیمرها توسط روش طیف سنجی ir شناسایی و پایداری گرمایی آن ها توسط تجزیه های وزن سنجی حرارتی (tga) و تجزیه ی گرمایی تفاضلی (dta) بررسی شده است. در ادامه، ساختار این ترکیبات توسط بلورنگاری پرتو...

Journal: :The Journal of Experimental Medicine 1944
W. M. Stanley

The sedimentation behavior of influenza virus in dilute solutions of electrolyte was found to be quite variable. At times the virus activity appeared to sediment at a rate comparable with that of particles about 80 to 120 mmicro in diameter, at other times at a rate comparable with that of particles about 10 mmicro in diameter, and at still other times the bulk of the activity appeared to sedim...

2012
Daniel J. Nowacki Alexander R. Horner-Devine Jonathan D. Nash David A. Jay

We compute rates of sediment removal from the Columbia River, USA plume near field using a control volume technique. By using data from repeated transect passes along the plume axis, we account for variations in plume width, depth, and velocity, and we construct a framework for determining the dominant terms in the complete sediment balance. The contribution due to turbulent sediment flux is es...

Journal: :Environmental research 2007
David H Schoellhamer Thomas E Mumley Jon E Leatherbarrow

Water-quality managers desire information on the temporal and spatial variability of contaminant concentrations and the magnitudes of watershed and bed-sediment loads in San Francisco Bay. To help provide this information, the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) takes advantage of the association of many contaminants with sediment particles by con...

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