نتایج جستجو برای: dust

تعداد نتایج: 41809  

1998
Frank J. Masci

If the background universe is observed through a significant amount of diffusely distributed foreground dust, then studies at optical wavelengths may be severely biased. Previous studies investigating the effects of foreground dust on background sources assumed dust to be “compactly” distributed, ie. on scales comparable to the visible extent of normal galaxies. We show however that diffuse dus...

ژورنال: زیست شناسی دریا 2021
Mobarak Hassan, Elham ,

Dust is a natural process in the desert areas. Strong winds on the dry soil surface make the particulate matter suspended in the air near the ground. In recent years, the influence of several natural factors has led to the further spread of dust in the western and southwestern parts of Iran. A storm take placed in the Khuzestan province and the northwest of the Persian Gulf, in February 17-19, ...

Irannejad, Parviz, Rezazadeh, Maryam, Shao, Yaping,

Extended abstract 1- INTRODUCTION        Atmospheric aerosols, solid and liquid particles in the atmosphere, play a crucial role in the atmospheric radiation equilibrium. These particles have an influence on the scattering and absorption of short wavelength radiation, and on the other hand, affect radiation absorption and emission in long wavelengths. Dust particles are among the importan...

2016
Ryan McKinnon Paul Torrey Mark Vogelsberger

We introduce a dust model for cosmological simulations implemented in the movingmesh code arepo and present a suite of cosmological hydrodynamical zoom-in simulations to study dust formation within galactic haloes. Our model accounts for the stellar production of dust, accretion of gas-phase metals onto existing grains, destruction of dust through local supernova activity, and dust driven by wi...

ژورنال: علوم آب و خاک 2014

Atmospheric dust is an important source of heavy metals, particularly in urban environments. Heavy metals can easily attach to dust particles and be distributed in large areas. The objective of this study was to evaluate the status of major heavy metals in the atmospheric dust of Isfahan and adjacent cities. A total of 144 dust samples were taken during a period from August to December 2010 fr...

Industrial activities and high traffic density are the most important heavy metal pollution sources in urban areas. Roadside dust created by atmospheric deposition can be one of the best indicators for heavy metal contamination levels. The present study reports the spatial distribution patterns and degree of heavy metal pollution (Cd, Cr, Ni, Pb, Zn, and As) in 50 roadside dust samples from urb...

مهدوی آکردی, مهدی, رقیمی, مصطفی , شمعانیان, غلامحسین , قلی پور, محسن ,

Portland cement could be produced by heating the raw materials (clay, limestone) about 1500°C which clinker will be formed. Geochemical and mineralogical studies of clinker, Portland cement, cement kiln dust and cement mill dust have been carried out by optical microscopy, X-ray diffraction and X-ray florescence. In phase system diagram (CaO-Al2O3-SiO2), chemical components of clinker cement oc...

Introduction Dust storms as one of the environmental hazards of the arid regions of the globe, including the southern, southwestern, eastern and central parts of Iran, has caused many environmental problems that confirm the need for studying and crisis managing its in scientific and executive congresses. Therefore, the present study attempts to evaluate the effects of climate elements on tempe...

2005
Dirk Goossens

Many stone-covered surfaces on Earth are subject to aeolian deposition of atmospheric dust. This study investigates how the deposition of dust is affected when rock fragments become gradually more embedded in the ground or, inversely, become more concentrated on the surface. Experiments were executed in an aeolian dust wind tunnel with eight different types of pebbles. The following parameters ...

2014
P. Dagsson-Waldhauserova O. Arnalds H. Olafsson

The long-term frequency of atmospheric dust observations was investigated for the southern part of Iceland and interpreted together with earlier results obtained from northeastern (NE) Iceland (Dagsson-Waldhauserova et al., 2013). In total, over 34 dust days per year on average occurred in Iceland based on conventionally used synoptic codes for dust observations. However, frequent volcanic erup...

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