نتایج جستجو برای: sand source

تعداد نتایج: 445545  

Journal: :Environmental toxicology and chemistry 2011
Ian J Murphy Joel R Coats

Atrazine is a widely used herbicide in agriculture. Non-point source contamination of groundwater and drinking water may pose a significant threat to humans, wildlife, and the environment. Phytoremediation may provide a cost-effective strategy for reducing non-point source contamination of atrazine from agricultural runoff. Previous studies have shown that the rhizosphere of the native prairie ...

2009
Jasper F. Kok Nilton O. Renno

[1] Wind-blown sand, or ‘saltation,’ creates sand dunes, erodes geological features, and could be a significant source of dust aerosols on Mars. Moreover, the electrification of sand and dust in saltation, dust storms, and dust devils could produce electric discharges and affect atmospheric chemistry. We present the first calculations of electric fields in martian saltation, using a numerical m...

Journal: :desert 2008
n. mashhadi h. ahmadi m. r. ekhtesasi s. feiznia g. feghhi

wind regime and sand grain size are two of the factors that determine the morphology and dynamics of sand dunes in desert areas. regarding the importance of wind effects on sand dunes especially in iran, in this study, khartooran erg was analyzed to determine wind direction and to detect sand source sites. khartooran erg is located on eastern north of iran and lies in khorasan razavi and semnan...

Journal: :journal of agricultural science and technology 2012
s. h. sadeghi m. kiani harchegani

soil erosion causes sediments to be detached from their source materials and transported as suspended particles. the present study was conducted to evaluate the effects of sand exploitation on the distribution of suspended sediments in the educational and research forest watershed of tarbiat modares university, which comprises approximately 50,000 ha. fifty-one water samples were collected befo...

Journal: :Physical review letters 2008
Jasper F Kok Nilton O Renno

Wind-blown sand, or "saltation," is an important geological process, and the primary source of atmospheric mineral dust aerosols. Significant discrepancies exist between classical saltation theory and measurements. We show here that these discrepancies can be resolved by the inclusion of sand electrification in a physically based saltation model. Indeed, we find that electric forces enhance the...

2013
Marcia I. Endres

Organic bedding sources are becoming more expensive and difficult to find. Sand can be considered the ideal bedding source for dairy cows; however, not all producers consider sand a feasible alternative for their operation. Inherent properties of sand can make it difficult to handle in some manure systems. Large amounts of bedding can be obtained from mechanical liquidsolid separation of manure...

The operation of sand transport by erosive winds and its sedimentation around the obstacles such as plants leads to the appearance of the eco-geomorphologic phenomenon of nebka dunes in dry seasons of Golestan province. This study aims to identify the physicochemical characteristics of nebka sediments and compare its results with adjacent lands. Hence, the grain size distribution and morph...

2003
Duane Ono Scott Weaver Ken Richmond

An extensive sand flux monitoring network was installed on the dry lake bed at Owens Lake, California to determine hourly PM-10 emissions. The network consisted of 135 co-located electronic and passive sand flux samplers covering 135 square kilometers of the lake bed. The network measured the hourly sand flux at each site for 30 months. Previous researchers found that PM-10 emissions due to win...

2013
Thomas M. Mascari Hanafi A. Hanafi Ryan E. Jackson Souâd Ouahabi Btissam Ameur Chafika Faraj Peter J. Obenauer Joseph W. Diclaro Lane D. Foil

BACKGROUND Leishmaniasis remains a global health problem because of the substantial holes that remain in our understanding of sand fly ecology and the failure of traditional vector control methods. The specific larval food source is unknown for all but a few sand fly species, and this is particularly true for the vectors of Leishmania parasites. We provide methods and materials that could be us...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه گیلان - دانشکده فنی 1392

در این پایان نامه مبدل های امپدانسی بطور خلاصه با عنوان (z-source converter) نامگذاری شده است. این مبدل در همه اشکال انتقال توان بصورت های dc به ac، ac به dc، ac به ac و dc به dc کابرد دارد. مبدل منبع امپدانسی از یک شبکه امپدانسی جالب بین یک منبع تغذیه و بار یا مبدل های دیگر برای دستیابی به ویژگی های منحصربفردی که در vsi و csi وجود ندارد، بهره می گیرد. در مبدل های منبع امپدانسی موانع و محدودیت ...

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