نتایج جستجو برای: lettau equation. in view of wind erosion power

تعداد نتایج: 24502573  

Journal: :مرتع و آبخیزداری 0
طیبه مصباح زاده دانشجوی دکتری بیابان زدایی، دانشکده منابع طبیعی، دانشگاه تهران، ایران حسن احمدی استاد دانشگاه آزاد اسلامی، واحد علوم تحقیقات، تهران، ایران

sand dunes mobility is one of the serious problems in arid regions. since wind regime is one of the important factors in sand dunes formation, its frequency, direction and magnitude can be effective. amount of wind energy and its directional variability (wind regime) have significant control on the morphology and maintenance of aeolian landforms. by recognizing of morphometric and morphodynamic...

Journal: :تحقیقات جغرافیایی 0
طیبه مصباح زاده حسن احمدی حسن احمدی

the main objective of this study is evaluation and wind statistic analysis, investigation of wind regime role on discharge flow and direction of sediments transferring in the case study. thus, sabzevar station anemometer data duration 10 years statistic period (1996-2005) analyzed. sand drift potential amount of study area is 160.9 v.u and result drift directionâ is west as well as sand flux is...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده فنی 1391

the study of air infiltration into the buildings is important from several perspectives that may be noted to energy and design of hvac systems, indoor air quality and thermal comfort and design of smoke control systems. given the importance of this issue, an experimental and numerical study of air infiltration through conventional doors and windows has been explored in iran. to this end, at fir...

Journal: :desert 2014
tayyebeh mesbahzadeh hasan ahmadi

wind regime data from the jask meteorological station from a 20-year statistical period (1985-2005) was analyzedusing the fryberger method to investigate sand drift potential (dp) in this area. the resultant drift potential anddirectional variability of wind were calculated and illustrated. average annual sand dp was estimated to be 460vector units (vu), and the sand flux is 51 m3/m.year. there...

Journal: Desert 2014

Wind regime data from the Jask meteorological station from a 20-year statistical period (1985-2005) was analyzedusing the Fryberger method to investigate sand drift potential (DP) in this area. The resultant drift potential anddirectional variability of wind were calculated and illustrated. Average annual sand DP was estimated to be 460vector units (VU), and the sand flux is 51 m3/m.year. There...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده علوم 1390

any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...

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...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیخ بهایی - دانشکده زبانهای خارجی 1391

phatic communion is a cultural concept which differs across cultures. according to hofstede (2001), the u.s. tends to have individualistic culture; however, asian countries tend to have collectivistic cultures. these cultures view phatic communion differently. in individualistic cultures like u.s., phatic communion reflects speakers’ socio-cultural relationships in conversations. to see whether...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه یزد - دانشکده جغرافیا 1392

the west of esfahan province, iran, is one of the most important agricultural areas throughout the country due to the climate variability and life-giving water of zayanderood river. rice is one of the major and economic crops in this area. the most important climatic elements in agricultural activities which should be considered include temperature, relative humidity, precipitation and wind. so...

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

the quest for power has formed much of the world history especially in 20th and 21st centuries. oil (energy) particularly after industrial revolution has been a tool for conquest and power and has been transformed to a geopolitical issue. from a geopolitical point of view this has been the case for the last two centuries in central asia and caucasus. central asia and caucasus has always been...

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