نتایج جستجو برای: oven measurement particles of dusts were done by a particle size distribution instrument

تعداد نتایج: 23705148  

ژورنال: علوم آب و خاک 2002
احمد جلالیان, , حمیدرضا کریم‌ زاده, ,

For the study of field wind erosion and the design and evaluation of wind erosion control techniques, detailed observations of soil particle transport and vertical destribution of eroded soil particles are needed. The objectives of this study were: 1) To describe one device for soil transport particle measurement, i. e. the BSNE sediment catcher and 2) To assess vertical distribution of wind–er...

F. Bustanafruz M. Fazli M. Jafar-Tafreshi,

Aluminum sulfate nano structures have been prepared by solution combustion synthesis using aluminum nitrate nonahydrate (Al(NO3)3.9H2O) and ammonium sulfate ((NH4)2SO4). The resultant aluminum sulfate nano structures were calcined at different temperatures to study thermal  decomposition of aluminum sulfate. The crystallinity and phase of  the as-synthesized and calcined samples were char...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده ادبیات و علوم انسانی 1391

the present study aimed at exploring cognitions of iranian english teachers within the context of english for academic purposes (eap). to this end, the cognitions of two groups of eap teachers with respect to their pedagogical content knowledge (pck) and their sense of professional identity (pi) were probed. two language teachers and two content instructors who had at least five years of eap te...

2011
Thomas M. Holsen Suresh Dhaniyala Philip K. Hopke

Objectives. Current efforts to study fugitive dust (FD) are hampered by the lack of an effective, real-time instrument to measure the broad range of particle sizes that make up FD. To meet this need the overall objective of this project was to develop and evaluate a novel instrument capable of measuring, in real-time, ambient concentrations of particles between approximately 2 and 100 μm. This ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد - دانشکده ادبیات و علوم انسانی دکتر علی شریعتی 1391

this ethnographic case study research was carried out in a private school setting in the context of iran. the research tried to explore the analysis and identity construction of a group of learners and teachers along with the content analysis of books on the basis of four types of commodified, political, national and narrative identities. how english language learners and teachers in an informa...

Journal: :مهندسی بیوسیستم ایران 0
حامد توکلی دکتری، دانشگاه تهران سید سعید محتسبی استاد، دانشگاه تهران علی جعفری دانشیار، دانشگاه تهران

a prototype of a straw chopper, equipped with a discharge system was designed and fabricated in the department of mechanics of agricultural machinery, university of tehran, karaj, iran. to test for the effective performance of the machine, the effects of such parameters as: drum speed (at three levels of: 400, 540, and 800 rpm), screen size (at two levels: 2.5 and 4 cm), and number of blades on...

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...

In this study, spherical Nb2O5 nanoparticles were synthesized by a novel chemical method as a simple, robust, surfactant-free, non-toxic and widely applicable approach. In order to investigate the effect of initial concentration on particle sizes, nanoparticles with different initial concentration were synthesized. Ultrasonic assisted method was applied and the effects of ultrasonic treat...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده زبانهای خارجی 1392

the aim of the current study was to investigate the relationship among efl learners learning style preferences, use of language learning strategies, and autonomy. a total of 148 male and female learners, between the ages of 18 and 30, majoring in english literature and english translation at islamic azad university, central tehran were randomly selected. a package of three questionnaires was ad...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سمنان - دانشکده مهندسی موادو متالورژی 1393

the aim of this paper is eliminating cr(vi) by natural hap. hap is a inexpensive material which is used from bovine critical bone ash in order to remove heavy metal ions like cr(vi). some experiments in different ph are performed (ph=2,3,7). maximum adsorption was appeared at ph=2, dosage=0.3 gr, c0=10 mg/l. cr(vi) removal depends on ph value and initial amount of cr(vi) result of experiments w...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید