نتایج جستجو برای: the index tiidi get less value for sky without dust and cloud than dust therefore

تعداد نتایج: 22681861  

Journal: :جغرافیا و مخاطرات محیطی 0
فهیمه محمدی سمیه کمالی مریم اسکندری

1. introduction dust phenomenon which occurs in arid and semiarid lands of the world is closely related to climatic characteristics of the region. according to the world meteorological organization (wmo), whenever wind speed exceeds 15 meter per second and horizontal visibility reduces to less than 1 km in a station, dust storm is reported (goudie & mideleton, 2006). great storms are created wh...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد گرمسار - دانشکده زبانهای خارجی 1389

previous studies have aimed at testing a hypothesis but the present study is data-first research in which researcher tries to form a theory from data rather than the use of data to test a hypothesis. this study aims at exploring teachers perceptions of the strengths and weaknesses of the current syllabus for college preparatory course. eight experienced teachers were selected to collect data du...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت دبیر شهید رجایی - دانشکده علوم انسانی 1392

this study investigated the impact of explicit instruction of morphemic analysis and synthesis on the vocabulary development of the students. the participants were 90 junior high school students divided into two experimental groups and one control group. morphological awareness techniques (analysis/synthesis) and conventional techniques were used to teach vocabulary in the experimental groups a...

ژورنال: علوم آب و خاک 2019

Heavy metals in street dust, as one of the most important environmental consequences of human activities, have attracted many researchers' attention in recent years due to their toxicity and sustainability. Therefore, this study aimed to investigate the hazard of heavy metals (lead, zinc, copper, chrome, cadmium, nickel, vanadium, arsenic and cobalt) on human health in street dust in Dezful. To...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد 1388

abstract following innovations in the field of elt, a new topic which has recently attracted a lot of attention is metaphor analysis. although this area of research is still in its infancy in elt, it seems that the idea can shed more light on the puzzle of english language learning and teaching. therefore, the major aim of this study is to analyze language learning and teaching in formal a...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی 1389

after the soviet union dissolution, a chaotic period was begun in the russia. russia lost its glory and felt disgrace. the first group of elites came to power under yeltsin; they tried to re-define russia’s identity as a european country and build a foreign policy on this baseline. therefore russia tried to become closer with the west especially with the u.s. according to their view the sovie...

Journal: Desert 2012
H. Ahmadi M. Yadegari M.A. Saremi Naeini

In order to recognize the wind erosion situation of a region, the survey of its windiness is not sufficient and the physical characteristics of earth are of importance too. In fact, the outbreak of dust storms in a region is due to the sensitivity of earth and domination of wind in that region. In this investigation we have tried to find a way for determining the regions in which a dust storm i...

Bidabadi , M, Sedighi , M. , Seyedi , M. ,

  The results of an experimental study of the combustion of aluminum particles in N2/O2 gas mixtures are presented and interpreted. This research focuses on measurement of flame speed and combustion velocity in aluminum particle dust cloud combustion. The dust dispersion technique uses an annular high-speed jet which disperses dust continuously supplied via a piston-type dust feeding system. Pa...

Journal: :محیط شناسی 0
مهدیه سلمان زاده کارشناسی ارشد مهندسی محیط زیست، دانشکدة مهندسی عمران، دانشگاه علم و صنعت ایران محسن سعیدی دانشیار دانشکدة مهندسی عمران، دانشگاه علم و صنعت ایران غلامرضا نبی بیدهندی استاد گروه مهندسی محیط زیست دانشکدة محیط زیست، دانشگاه تهران

street dusts are suspended particle matters in the air from different natural and anthropogenic sources that may fall out because of their size and density. forty nine street dust samples were collected from some main streets of eastern and southern parts of tehran. one other sample was also collected from iran university of science and technology central campus for comparisons during summer un...

Background: The release of metals from industrial factories is one of the most important sources of environmental pollution. The present study aimed to determine the concentration of heavy metals like cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), and lead (Pb) in dust around the cement factory. Methods: A total of 22 dust samples were collected from areas around the cement factory...

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