نتایج جستجو برای: variable radiation

تعداد نتایج: 492739  

Journal: :Radiation protection dosimetry 2014
Sascha Reinhardt

In environmental radiation monitoring, the time-variable natural gamma radiation background complicates the nuclide identification and analysis of a gamma spectrum. A full spectrum analysis based on the noise adjusted singular value decomposition method for the description of the time-variable background and adjustment calculations is a possible analysis method, which may provide advantages com...

Journal: :مهندسی بیوسیستم ایران 0
سید حنیف رضا معتمد الشریعتی دانشجوی دکترای مکانیزاسیون کشاورزی دانشگاه تهران حسین مبلی هیئت علمی پردیس کشاورزی و منابع طبیعی دانشگاه تهران محمد شریفی هیئت علمی پردیس کشاورزی و منابع طبیعی دانشگاه تهران حجت احمدی هیئت علمی پردیس کشاورزی و منابع طبیعی دانشگاه تهران

one of the most main head in governments is to achieve the energy for their countries. as the fossil sources are at their ends and also they cause greenhouse emission and environment pollution, shifting to renewable sources of energy is an indispensable alternative for most countries. the sun is the most important renewable energy source. to assessment reachable solar radiation in mashhad from ...

The present study deals with the analysis of the effects of radiative heat transfer of micropolar fluid flow over a porous and stretching sheet in the presence of magnetic field. The dynamic viscosity and thermal conductivity coefficient have formulated by temperature-dependent relations to obtain more exact results. The flow is supposed two-dimensional, incompressible, steady and laminar and t...

The current article has investigated unsteady convective flow for MHD non-Newtonian Powell-Eyring fluid embedded porous medium over inclined permeable stretching sheet. We have pondered the thermophoresis parameter, chemical reaction, variable thermal conductivity, Brownian motion, variable heat source and variable thermal radiation in temperature and concentration profiles. Using similar trans...

Journal: :Physical review letters 2008
M Labat M Hosaka M Shimada M Katoh M E Couprie

Seeded single pass free-electron lasers are promising coherent, short-duration, and intense light sources, from the visible to x rays. Operated with adjustable undulators, they are also a unique device for providing fully variable polarized radiation. We report here the first seeding of helical undulators with a variable polarized source. We demonstrate that the adjustment of the seed polarizat...

Journal: :Physical review letters 2007
S A Slutz R A Vesey M C Herrmann

An approach is presented to design inertial-fusion capsules compensated for time-dependent radiation-drive asymmetries. This approach uses in depth variable doping of the capsule ablator, i.e., the addition of small amounts of material to tailor the opacity. Simulations show that an inertial-fusion capsule, using a beryllium ablator variably doped with gold, can be designed to compensate for a ...

this thesis attempts to investigate the effects of prelistening activities on enhancing iranian efl learners` listening comprehension. the present study investigated ways in which learners` background knowledge could be activated in order to enhance their l2 listening comprehension by limiting the number of possible text interpretations prior to listening. the experiments conducted in this study examined the effect of prior knowledge and vocabulary teaching on iranian efl learners listening comprehension. the current study has two purposes: one is to investigate the effect of background knowledge on the second language listening comprehension of iranian intermediates and the other is to determine whether second language is facilitated by the introduction of unknown vocabularies in the form of prelistening activities. to conduct the study different instruments such as listening proficiency test and four listening tests such as pre and posttests were used and various statistical processes and techniques including paired-sample t-test, and analysis of variance (anova) were used. the findings of this study supported all three hypotheses tested. differences were found between the means of preteaching vocabulary variable, the background knowledge activation variable, and mean difference between these two strategies variable. subjects scored higher when the unknown words were taught in advance. likewise, subjects scored higher when they were asked some relevant questions about the topic than on those without them. there was, in addition, a significant difference between the means of preteaching vocabulary strategy and background knowledge activation strategy. in fact, preteaching vocabulary had a better effect in enhancing the students’ listening comprehension, in comparison to background knowledge activation strategy.

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده زبانهای خارجی 1390

this thesis attempts to investigate the effects of prelistening activities on enhancing iranian efl learners` listening comprehension. the present study investigated ways in which learners` background knowledge could be activated in order to enhance their l2 listening comprehension by limiting the number of possible text interpretations prior to listening. the experiments conducted in this stud...

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